CHAPTER 1

INTRODUCTION & HISTORY

1.1 Introduction

Every day of your computing life, you reach out for the mouse whenever you want to move

the cursor or activate something. The mouse senses your motion and your clicks and sends

them to the computer so it can respond appropriately. An ordinary mouse detects motion in

the X and Y plane and acts as a two dimensional controller. It is not well suited for people

to use in a 3D graphics environment. Space Mouse is a professional 3D controller

specifically designed for manipulating objects in a 3D environment. It permits the

simultaneous control of all six degrees of freedom - translation rotation or a combination. .

The device serves as an intuitive man-machine interface.

The predecessor of the space mouse was the DLR controller ball. Space mouse has its

origins in the late seventies when the DLR (German Aerospace Research Establishment)

started research in its robotics and system dynamics division on devices with six degrees of

freedom (6 dof) for controlling robot grippers in Cartesian space. The basic principle behind

its construction is mechatronics engineering and the multisensory concept. The space mouse

has different modes of operation in which it can also be used as a two-dimensional mouse.

Space mouse opens a new age for man-machine communication. This device is based

on the technology used to control the first robot in space and has been adapted for a wide

range of tasks including mechanical design, real time video animation and visual

simulation. It has become a standard input device for interactive motion control of three-

dimensional graphic objects in up to six degrees of freedom. Space mouse works with

standard serial mouse interface without an additional power supply. The ergonomic design

allows the human hand to rest on it without fatigue. Thus flying an object in six degrees of

freedom is done without any strain.

A space mouse is a device similar to a joystick in purpose, but it also provides

movement control with six degrees of freedom. This block reads the status of the space

mouse and provides some commonly used transformations of the input. The Space Mouse

Input block supports current models of 3–D navigation devices manufactured by

3Dconnexion. The basic principle behind its construction is mechatronics engineering and

the multisensory concept.[1]

1

1.2 History

The predecessor of the space mouse was the DLR controller ball. Space mouse has its

origins in the late seventies when the DLR (German Aerospace Research Establishment)

started research in its robotics and system dynamics division on devices with six degrees of

freedom (6 dof) for controlling robot grippers in Cartesian space. The basic principle behind

its construction is mechatronics engineering and the multisensory concept. The space mouse

has different modes of operation in which it can also be used as a two-dimensional mouse.

The result of years of development for man-machine communication in aerospace and

robotic applications the predecessor of the European Space Mouse (known in the US and

Asia as Magellan) was the DLR control ball used to control the first robot in space

remotely. It flew in NASA’s Space Shuttle Columbia in 1993. In fact Magellan has its

origins in the late seventies when the DLR (German Aerospace Research Establishment)

started research in its robotics and system dynamics division on devices with six degrees of

freedom (6 dof) for controlling robot grippers in Cartesian space.

After lengthy experiments it turned out around 1981 that integrating a six-axis force-

torque sensor (three force three torque components) into a plastic hollow ball was the

optimal solution. Such a ball registered the linear and rotational displacements as generated

by the forces and torques of a human hand which were then transformed computationally

into translational and rotational motions and speeds. The first force-torque sensor used was

based on strain gauge technology. Wide commercial distribution was prevented by the high

price of about $8000 per unit.

It took until 1985 for the DLR’s developer group to design a much cheaper optical

measuring system based on six one-dimensional position detectors. The whole electronics

including computational processing on a one-chip processor was already integrable into the

ball by means of two small double-sided surface mount device boards. The manufacturing

costs were reduced to below $1000 but the sales price still hovered in the area of $3000.

Only a few hundred were sold. The original hopes of the developer group that license

companies might be able to develop devices towards much lower manufacturing costs did

not materialize. On the other hand with the passing of time other ball systems appeared on

the market which differed in the type of measuring system. DLR’s development group spun

off a company called Space Control whose objectives were to redesign the control ball idea

while retaining the optoelectronic measuring principle reducing manufacturing costs to a

fraction of the previous amount so that it could approach the pricing level of high end PC

2

devices. The new manipulation device should be able to function as a conventional mouse

and appear like one yet maintain its versatility in a real workstation environment.

Ergonomically the mouse has a very flat and compact design allowing the palm of the

hand to rest naturally on the device without fatigue leaving all the fingers free to interact

with the mouse cap. Very slight pressure to push pull or twist the cap in any one or more of

the six degrees of freedom is enough to move the object in the screen. Pulling the cap in the

Z-direction corresponds to the zooming function pushing it distances the object relative to

the viewer. Moving the cap in the X or Y directions drags the object horizontally and

vertically on the screen. Twisting the cap over one of the main axes or any combination of

them rotates the object over the corresponding axis on the screen.

Within seconds of using the device the interaction with the cap becomes intuitive.

This means that the user handles the object on the screen as if he were holding it in his own

left hand observing or guiding it with high precision and helping the right hand to undertake

the correct constructive actions on specific points lines or surfaces simply by unconsciously

bringing to the front the appropriate perspective view of any necessary detail of the object.

And with the integration of nine additional key buttons any macro function can be mapped

onto one of the keys thus allowing the user most frequently used functions to be called by a

slight finger touch from the left hand.

Now the European Space Mouse is becoming something of a standard input device for

interactive motion control of 3D graphic objects in the Catia working environment and for

many other applications. There are over 120 installations in Europe and US licensee

Logitech aims to make it the world standard for 3 graphics interfaces. Silicon Graphics has

integrated the interface driver into its new operating system and other leading CAD systems

such as Pro/Engineer Ideas Solidworks and Cadds5 have dedicated Magellan drivers.

Place your fingers gently on the controller's cap. The cap senses pressure you apply to

it - pushes, pulls and twists - and uses that information to correspondingly move your

model, camera or eye point on the screen. Pull up or push down to move your model,

camera or eye point up or down. Push left or right to move your model left or right. Pull

towards you or push away to move your model nearer or farther away. Orient your model

on the screen by simply twisting in any direction to rotate it around the X, Y or Z axis

(pitch, roll and yaw). You will quickly be able to combine all movements and control your

3D models with six degrees of freedom. The amount of pressure you apply controls speed

of movement. A light touch moves your models slowly and accurately; just increase

3

pressure to increase speed. It will be like holding your model in your hand - interacting in

3D as you do in the real world. The ergonomic design allows the human hand to rest on it

without fatigue. Thus flying an object in six degrees of freedom is done without any strain.

This means that the user handles the object on the scren as if he were holding it in his own

left hand observing or guiding it with high precision and helping the right hand to undertake

the correct constructive actions on specific points lines or surfaces simply by unconsciously

bringing to the front the appropriate perspective view of any necessary detail of the object. [2]

Fig 1.1 Space Mouse

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CHAPTER 2

HOW DOES A COMPUTER MOUSE WORKS & 3D USER

INTERFACE

Mice first broke onto the public stage with the introduction of the Apple Macintosh in

1984, and since then they have helped to completely redefine the way we use

computers. Every day of our computing life, you reach out for your mouse whenever you

want to move your cursor or activate something. Your mouse senses your motion and your

clicks and sends them to the computer so it can respond appropriately.

2.1 Inside a Mouse

The main goal of any mouse is to translate the motion of your hand into signals that the

computer can use. Almost all mice today do the translation using five components:

Fig. 2.1 The guts of a mouse

1. A ball inside the mouse touches the desktop and rolls when the mouse moves.

2. Two rollers inside the mouse touch the ball. One of the rollers is oriented so that it

detects motion in the X direction, and the other is oriented 90 degrees to the first roller

so it detects motion in the Y direction.

3. When the ball rotates, one or both of these rollers rotate as well. The Fig. 3.3 shows the

two white rollers on this mouse.

4. The rollers each connect to a shaft, and the shaft spins a disk with holes in it.

When roller rolls, its shaft and disk spin. The Fig. 3.4 shows the disk.

5

Fig. 2.2 The exposed portion of the ball touches the desktop

Fig. 2.3 The rollers that touch the ball and detect X and Y motion

6

Fig. 2.4 A typical optical encoding disk

5. On either side of the disk there is an infrared LED and an infrared sensor. The

holes in the disk break the beam of light coming from the LED so that the infrared sensor

sees pulses of light.

Fig. 2.5 A close-up of one of the optical encoders

that track mouse motion: There is an infrared LED (clear) on one side of the disk

and an infrared sensor (red) on the other. The rate of the pulsing is directly related to the

speed of the mouse and the distance it travels.

6. An on-board processor chip reads the pulses from the infrared sensors and turns

them into binary data that the computer can understand. The chip sends the binary data

to the computer through the mouse's cord.

7

Fig. 2.6 The small processor

In this optomechanical arrangement, the disk moves mechanically, and an optical

system counts pulses of light. Each encoder disk has two infrared LEDs and two infrared

sensors, one on each side of the disk (so there are four LED/sensor pairs inside a

mouse). This arrangement allows the processor to detect the disk's direction of

rotation. There is a piece of plastic with a small, precisely located hole that sits

between the encoder disk and each infrared sensor. This piece of plastic provides a

window through which the infrared sensor can "see." The window on one side of the disk

is located slightly higher than it is on the other -- one-half the height of one of the holes in

the encoder disk, to be exact. That difference causes the two infrared sensors to see

pulses of light at slightly different times. There are times when one of the sensors

will see a pulse of light when the other does not, and vice versa. [1]

Fig. 2.7 Conventional computer mouse

2.2 3D User Interface

For a typical computer display, three-dimensional is a misnomer—their displays are two-

dimensional. Three-dimensional images are projected on them in two dimensions. Since

this technique has been in use for many years, the recent use of the term three-

dimensional must be considered a declaration by equipment marketers that the speed

of three dimension to two dimension projection is adequate to use in standard

graphical user interfaces. Three-dimensional graphical user interfaces are common in

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science fiction literature and movies, such as in Jurassic Park, which features Silicon

Graphics' three-dimensional file manager, "File system navigator", an actual file

manager that never got much widespread use as the user interface for a Unix

computer. In science fiction, three-dimensional user interfaces are often immersible

environments like William Gibson's Cyberspace or Neal Stephenson's Metaverse.

Three-dimensional graphics are currently mostly used in computer games, art and

computer-aided design (CAD). There have been several attempts at making three-

dimensional desktop environments like sun's Project Looking Glass or SphereXP from

Sphere Inc.

Fig. 2.8 3D Interface

A three-dimensional computing environment could possibly be used for collaborative

work. For example, scientists could study three-dimensional models of molecules in a

virtual reality environment, or engineers could work on assembling a three-

dimensional model of an airplane. This is a goal of the Croquet project and Project

Looking Glass by Java. The use of three-dimensional graphics has become

increasingly common in mainstream operating systems, but mainly been confined to

creating attractive interfaces—eye candy—rather than for functional purposes only possible

using three dimensions. For example, user switching is represented by rotating a

cube whose faces are each user's workspace, and window management is represented in

the form of Exposé on Mac OS X, or via a Rolodex-style flipping mechanism in

Windows Vista.

In both cases, the operating system transforms windows on-the-fly while continuing to

update the content of those windows workspace, and window management is represented in

the form of Exposé on Mac OS X, or via a Rolodex-style flipping mechanism in Windows

Vista. In both cases, the operating system transforms windows on-the-fly while

9

continuing to update the content of those windows. Interfaces for the X Window System

have also implemented advanced three-dimensional user interfaces through compositing

window managers such as Beryl and Compiz using the AIGLX or XGL architectures,

allowing for the usage of OpenGL to animate the user's interactions with the desktop.

Another branch in the three-dimensional desktop environment is the three-dimensional

graphical user interfaces that take the desktop metaphor a step further, like the

BumpTop, where a user can manipulate documents and windows as if they were "real

world" documents, with realistic movement and physics. With the current pace on

three-dimensional and related hardware evolution, projects such these may reach an

operational level soon.

The GUI was developed at Xerox PARC in the late seventies for the Star system. It was

first successfully commercialised by Apple with the Macintosh computer in the early

eighties and has since become an integral part of every modern operating system for

personal computers and graphics workstations. One reason for this growth is productivity: a

number of studies have shown GUIs, with their direct manipulation style of interaction,

enhance productivity. Another reason is subjective preference: people express a preference

for GUI interfaces. Coupled with the rise of the GUI has been a general elevation of the

importance of the user interface, which is now recognised as a key, and sometimes central,

component of an interactive product or environment.

Today's GUI depended on declining hardware prices to make it affordable at the low-

end of the computer market -- personal computers. The same trend, a doubling of

performance approximately every 18 months to two years (widely known as Moore's Law),

now means personal computers are capable of performing interactive 3D graphics. In

tandem with improving hardware performance, graphics libraries such as OpenGL which

were previously available only on workstations have now become available for personal

computers.

We believe that 3D GUIs -- graphical user interfaces which utilise 3D graphics -- offer

significant potential for improvement over today's 2tex2html_wrap_inline179D GUIs, and

furthermore, that it is now, or very shortly will be, possible to run such interfaces on

personal computers. In this paper, we discuss elements of a prototype 3D GUI we are

developing and discuss some early feedback from usability tests.

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CHAPTER 3

MECHATRONICS

3.1 What is Mechatronics Engineering?

Mechatronics is the combination of mechanical engineering, electronic engineering,

computer engineering, software engineering, control engineering, and systems design

engineering in order to design and manufacture useful products. Mechatronics is a

multidisciplinary field of engineering, that is to say it rejects splitting engineering into

separate disciplines. Originally, mechatronics just included the combination between

mechanics and electronics hence the word is only a portmanteau of mechanics and

electronics.

Mechatronics is concerned with the design automation and operational

performance of electromechanical systems. Mechatronics engineering is nothing new;

it is simply the applications of latest techniques in precision mechanical engineering,

electronic and computer control, computing systems and sensor and actuator

technology to design improved products and processes. The basic idea of Mechatronics

engineering is to apply innovative controls to extract new level of performance from a

mechanical device.

It means using modem cost effective technology to improve product and process

performance, adaptability and flexibility. Mechatronics covers a wide range of

application areas including consumer product design, instrumentation, manufacturing

methods, computer integration and process and device control. A typical Mechatronic

system picks up signals processes them and generates forces and motion as an

output. In effect mechanical systems are extended and integrated with sensors (to

know where things are), microprocessors (to work out what to do), and controllers

(to perform the required actions).[11]

The word Mechatronics came up describing this fact of having technical

systems operating mechanically with respect to some kernel functions but with more

or less electronics supporting the mechanical parts decisively. Thus we can say that

Mechatronics is a blending of Mechanical engineering, Electronics engineering and

11

Computing. These three disciplines are linked together with knowledge of management,

manufacturing and marketing. Mechatronics is centred on mechanics, electronics,

computing, control engineering, molecular engineering (from nanochemistry and biology),

and optical engineering, which, combined, make possible the generation of simpler,

more economical, reliable and versatile systems.

The portmanteau "mechatronics" was coined by Tetsuro Mori, the senior

engineer of the Japanese company Yaskawa in 1969. An industrial robot is a prime

example of a mechatronics system; it includes aspects of electronics, mechanics, and

computing to do its day-to-day jobs. Engineering cybernetics deals with the question of

control engineering of mechatronic systems. It is used to control or regulate such a

system (see control theory).

Fig. 3.1 Mechatronics

Through collaboration, the mechatronic modules perform the production goals

and inherit flexible and agile manufacturing properties in the production scheme.

Modern production equipment consists of mechatronic modules that are integrated

according to control architecture. The most known architectures involve hierarchy,

polyarchy, heterarchy, and hybrid. The methods for achieving a technical effect are

12

described by control algorithms, which might or might not utilize formal methods in their

design. Hybrid systems important to mechatronics include production systems, synergy

drives, planetary exploration rovers, automotive subsystems such as anti-lock braking

systems and spin-assist, and every-day equipment such as autofocus cameras, video,

hard disks, and CD players.

For most mechatronic systems, the main issue is no more how to implement a control

system, but how to implement actuators and what is the energy source. Within the

mechatronic field, mainly two technologies are used to produce the movement: the

piezo-electric actuators and motors, or the electromagnetic actuators and motors. Maybe

the most famous mechatronics systems are the well-known camera autofocus system

or camera anti-shake systems. Concerning the energy sources, most of the applications use

batteries. But a new trend is arriving and is the energy harvesting, allowing

transforming into electricity mechanical energy from shock, vibration, or thermal

energy from thermal variation, and so on.[1]

3.2 What do Mechatronics engineers do?

A mechatronics engineer unites the principles of mechanics, electronics, and computing to

generate a simpler, more economical and reliable system. Mechatronics is centered on

mechanics, electronics, computing, control engineering, molecular engineering (from

nanochemistry and biology), and optical engineering, which, combined, make possible the

generation of simpler, more economical, reliable and versatile systems. The portmanteau

"mechatronic" was coined by Tetsuro Mori, the senior engineer of the Japanese company

Yaskawa in 1969. An industrial robot is a prime example of a mechatronics system; it

includes aspects of electronics, mechanical , and computing to do its day-to-day jobs.

Mechatronics design covers a wide variety of applications from the physical

integration and miniaturization of electronic controllers with mechanical systems to th

control of hydraulically powered robots in manufacturing and assembling factories.

Computer disk drives are one example of the successful application of Mechatronics

engineering as they are required to provide very fast access precise positioning and

robustness against various disturbances.

An intelligent window shade that opens and closes according to the amount of

sun exposure is another example of a Mechatronics application. Mechatronics

engineering may be involved in the design of equipments and robots for under water

or mining exploration as an alternative to using human beings where this may be

13

dangerous. The portmanteau "mechatronic" was coined by Tetsuro Mori, the senior

engineer of the Japanese company Yaskawa in 1969.

In fact Mechatronics engineers can be found working in a range of industries and

project areas including:[1]

Design of data collection, instrumentation and computerized machine tools.

Intelligent product design for example smart cars and

automation for household transportation and industrial application.

Design of self-diagnostic machines, which fix problems on their own.

Medical devices such as life supporting systems, scanners and DNA

sequencing automation.

Robotics and space exploration equipments.

Smart domestic consumer goods Computer peripherals.

Security systems.

3.3 Mechatronic goals

3.3.1 Multisensory Concept

The aim was to design a new generation of multi-sensory lightweight robots. The

new sensor and actuator generation does not only show up a high degree of electronic

and processor integration but also fully modular hardware and software structures.

Analog conditioning, power supply and digital pre-processing are typical subsystems

modules of this kind. The 20khz lines connecting all sensor and actuator systems in a

galvanically decoupled way and high speed optical serial data bus (SERCOS) are the

typical examples of multi-sensory and multi actuator concept for the new generation

robot envisioned.

The main sensory developments finished with these criteria have been in the

last years: optically measuring force-torque-sensor for assembly operations. In a more

compact form these sensory systems were integrated inside plastic hollow balls, thus

generating 6-degree of freedom hand controllers (the DLR control balls). The SPACE-

MOUSE is the most recent product based on these ideas.

Stiff strain-gauge based 6 component force-torque-sensor systems.

Miniaturized triangulation based laser range finders.

Integrated inductive joint-torque-sensor for light-weight-robot.

14

In order to demonstrate the multi-sensory design concept, these types of sensors have

been integrated into the multi-sensory DLR-gripper, which contains 15 sensory

components and to our knowledge it is the most complex robot gripper built so far

(more than 1000 miniaturized electronic and about 400 mechanical components). It has

become a central element of the ROTEX space robot experiment. [1]

3.3.2 Applications of Mechatronics Engineering [1]

Machine vision

Automation and robotics

Servo-mechanics

Sensing and control systems

Automotive engineering, automotive equipment in the design of subsystems such as

anti-lock braking systems

Computer-machine controls, such as computer driven machines like IE CNC milling

machines

Expert systems

Industrial goods

Consumer products

Mechatronics systems

Medical mechatronics, medical imaging systems

Structural dynamic systems

Transportation and vehicular systems

CHAPTER 4

15

SPACE MOUSE

Space mouse is developed by the DLR (Deutsches Zenturum far Luft-und Raumfahrt)

institute of robotics and mechatronics.

4.1 Why 3D motion?

In every area of technology, one can find automata and systems controllable up to six

degrees of freedom- three translational and three rotational. Industrial robots made up the

most prominent category needing six degrees of freedom by maneuvering six joints to

reach any point in their working space with a desired orientation. Even broader there

have been a dramatic explosion in the growth of 3D computer graphics.

Already in the early eighties, the first wire frame models of volume objects

could move smoothly and interactively using so called knob-boxes on the fastest

graphics machines available. A separate button controlled each of the six degrees of

freedom. Next, graphics systems on the market allowed manipulation of shaded volume

models smoothly, i.e. rotate, zoom and shift them and thus look at them from any viewing

angle and position. The scenes become more and more complex; e.g. with a "reality

engine" the mirror effects on volume car bodies are updated several times per second - a

task that needed hours on main frame computers a couple of years ago.

Parallel to the rapid graphics development, we observed a clear trend in the

field of mechanical design towards constructing and modeling new parts in a 3D

environment and transferring the resulting programs to NC machines. The machines are

able to work in 5 or 6 degrees of freedom (dof). Thus, it is no surprise that in the

last few years, there are increasing demands for comfortable 3D control and

manipulation devices for these kinds of systems. Despite breathtaking advancements

in digital technology it turned out that digital man- machine interfaces like keyboards

are not well suited for people to use as our sensomotory reactions and behaviors are and

will remain analogous forever.

Users control three-dimensional movement by maneuvering SPACE MOUSE

"Classic" spring-mounted cap. Slight finger pressure on the cap will control an object in

up to 6 degrees of freedom (X, Y, Z, pitch, roll, and yaw movement)

simultaneously. The SPACE MOUSE "Classic" 3D Motion Controller is available for

16

both UNIX and PC platforms to be used with industry standard CAD/CAM, CAE

applications such as CATIA, Pro/ENGINEER, I-DEAS or AutoCAD.

Features:

Unprecedented ease of use for manipulating objects in 3D applications.

Calibration- and drift free sensor technology for high precision and unequaled

reliability.

Nine programmable buttons to customize user's preferences for motion control.

Finger operation for maximum precision and performance.

Certified by all major suppliers of CAD/CAM, CAE and visual simulation

products .

Benefits:

In CAD/CAM, CAE and visual simulation applications.

The 3D Motion Controller is used in conjunction with the normal mouse. As

the user positions the 3D object with Magellan & trade, the necessity of going

back and forth to a menu is eliminated. Thus, drawing times can be reduced by 20-

30%.

Increasing overall productivity.

Other benefits include an improved design comprehension and earlier detection of

design errors.

Contributing to faster time to market and cost savings in the design process.

SpaceMouse® Plus is the award-winning product in the line of professional 3D motion

controllers for industrial design and visual simulation applications. It provides

intuitive and precise interactive motion control of three-dimensional graphic objects in

up to six degrees of freedom simultaneously. This professional input device

dramatically increases productivity, improves object comprehension and helps detect

design errors earlier. Spacemouse Plus A user-friendly, soft coated cap (electrostatic,

ionised method of coating provides a better grip) with a distinctive grip area for thumb,

forefinger and middle finger supports virtually every single cap movement with the

uniquely soft, pressure-sensitive sensor.

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4.2 Degree of freedom

In mechanics degrees of freedom (DOF) is the number of parameters that define the

configuration of a mechanical system. The degrees of freedom of a body is the number of

independent parameters that define the displacement and deformation of the body. This is a

fundamental concept relating to systems of moving bodies in mechanical engineering,

aeronautical engineering, robotics, and structural engineering.

The position of a single car (engine) moving along a track has one degree of freedom,

because the position of the car is defined by the distance along the track. A train of rigid

cars connected by hinges to an engine still has only one degree of freedom because the

positions of the cars behind the engine are constrained by the shape of the track.

An automobile can be considered to be a rigid body traveling on a plane (a flat, two-

dimensional space). This body has three independent degrees of freedom consisting of two

components of translation and one angle of rotation. Skidding or drifting is a good example

of an automobile's three independent degrees of freedom. The position of rigid body in

space is defined by three components of translation and three components of rotation, which

means that it has six degrees of freedom.

Fig.4.1 Degree of freedom

The position of a n-dimensional rigid body is defined by the rigid transformation,

[T]=[A, d], where d is an n-dimensional translation and A is an nxn rotation matrix, which

has n translational degrees of freedom and n(n + 1)/2 rotational degrees of freedom. The

number of rotational degrees of freedom comes from the dimension of the rotation group

SO(n).

A non-rigid or deformable body may be thought of as a collection of many minute

particles (infinite number of DOFs); this is often approximated by a finite DOF system.

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When motion involving large displacements is the main objective of study (e.g. for

analyzing the motion of satellites), a deformable body may be approximated as a rigid body

(or even a particle) in order to simplify the analysis. The motion of a ship at sea has the six

degrees of freedom of a rigid body, which described as:

Translation:

1. Moving up and down (heaving)

2. Moving left and right (swaying)

3. Moving forward and backward (surging)

Rotation:

1. Tilting forward and backward (pitching)

2. Turning left and right (yawing)

3. Tilting side to side (rolling)

As defined above one can also get degree of freedom using minimum number of

coordinates required to specify a position.Applying it:

1.For a single particle we need 2 coordinates in 2-D plane to specify it's position and 3

coordinates in 3-D plane.Thus it's degree of freedom in 3-D plane is 3.

2.For a body consisting of 2 particles(ex.diatomic molecule) in 3-D plane with

constant distance between them(let's say d) we can show it's degree of freedom to be 5.

A system with several bodies would have a combined DOF that is the sum of the DOFs of

the bodies, less the internal constraints they may have on relative motion. A mechanism or

linkage containing a number of connected rigid bodies may have more than the degrees of

freedom for a single rigid body. Here the term degrees of freedom is used to describe the

number of parameters needed to specify the spatial pose of a linkage.

You can use your own arm to get an idea of the degrees of freedom that a robot arm

might have. Extend your arm straight out toward the horizon. Extend your index so it is

pointing. Keeping your arm straight, move it from the shoulder. You can move in three

ways. Up-and-down movement is called pitch. Movement to the right and left is called yaw.

You can also rotate your whole arm as if you were using it as a screwdriver. This is called

roll. Your shoulder has three degrees of freedom; pitch, yaw, and roll.[3]

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Fig. 4.2 Degree of freedom of hand

Now move your arm from the elbow only. This is rather hard to do without also

moving your shoulder. Holding your shoulder in the same position constantly, you will see

that your elbow joint has the equivalent of pitch in your shoulder joint. But that is all. Your

elbow, therefore, has one degree of freedom. Extend your arm toward horizon again. Now

move only your wrist. Try to keep the arm above the wrist straight and motionless. Your

wrist can bend up and down, side to side, and it can also twist a little. Your lower arm has

the same three degrees of freedom that your shoulder has (Most of the roll takes place all

along your arm below the elbow).

In total, your arm has seven degrees of freedom: three in the shoulder, one in the

elbow, and three in the arm below the elbow. Three degrees of freedom are sufficient to

bring the end of a robot arm to any point within its workspace, or work envelope, in three

dimensions. A specific type of linkage is the open kinematic chain, where a set of rigid links

are connected at joints; a joint may provide one DOF (hinge/sliding), or two (cylindrical).

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Such chains occur commonly in robotics, biomechanics, and for satellites and other space

structures. A human arm is considered to have seven DOFs.

A shoulder gives pitch, yaw, and roll, an elbow allows for pitch and roll, and a wrist

allows for pitch and yaw. Only 3 of those movements would be necessary to move the hand

to any point in space, but people would lack the ability to grasp things from different angles

or directions. A robot (or object) that has mechanisms to control all 6 physical DOF is said

to be holonomic. An object with fewer controllable DOFs than total DOFs is said to be non-

holonomic, and an object with more controllable DOFs than total DOFs (such as the human

arm) is said to be redundant.

In mobile robotics, a car-like robot can reach any position and orientation in 2-D

space, so it needs 3 DOFs to describe its pose, but at any point, you can move it only by a

forward motion and a steering angle. So it has two control DOFs and three representational

DOFs; i.e. it is non-holonomic. A fixed-wing aircraft, with 3–4 control DOFs (forward

motion, roll, pitch, and to a limited extent, yaw) in a 3-D space, is also non-holonomic, as it

cannot move directly up/down or left/right.

Table 4.1: SPACE MOUSE "Classic" - Product Specifications[1]

Operating Modes 3D interface (six degrees of freedom)

Translation Mode Only the translation coordinates (X, Y, X)

are reported

Rotation Mode Only the rotation coordinates (A, B, C)

are reported

Dominant Mode Only the coordinate with the greatest

magnitude is reported

Sensitivity Adjustable (real 600 speed levels resolution)

Buttons 9, programmable

Interface type RS232C Serial

Baud Rate 9600 baud

Connector DSUB 9 Female

Power Supply via serial port signals

Dimensions L x W x H: 163 x 112 x 40mm

Warranty 3 Years

21

Table 4.2: SPACE MOUSE "Plus" - Product Specifications[1]

Operating Modes 3D interface (six degrees of freedom)

Translation Mode Only the translation coordinates (X, Y, X)

are reported

Rotation Mode Only the rotation coordinates (A, B, C)

are reported

Dominant Mode Only the coordinate with the greatest

magnitude is reported

Sensitivity Adjustable (real 600 speed levels resolution)

Buttons 11, programmable

Interface type RS232C Serial

Baud Rate 9600 baud

Connector DSUB 9 Female

Power Supply via serial port signals

Dimensions L x W x H: 188 x 120 x 40mm

Warranty 3 Years

Fig.4.3 Spacemouse Plus

4.3 DSUB

22

The D-subminiature or D-sub is a common type of electrical connector. They are named for

their characteristic D-shaped metal shield. When they were introduced, D-subs were among

the smaller connectors used on computer systems.

A D-sub contains two or more parallel rows of pins or sockets usually surrounded by

a D-shaped metal shield that provides mechanical support, ensures correct orientation, and

may screen against electromagnetic interference. The part containing pin contacts is called

the male connector or plug, while that containing socket contacts is called the female

connector or socket. The socket's shield fits tightly inside the plug's shield. The plug also

may have screws on either side of the shield that fasten into holes in the socket (although

sometimes the screws are on the socket: see the DE9 pictured to the left). When screened

cables are used, the shields are connected to the overall screens of the cables. This creates

an electrically continuous screen covering the whole cable and connector system. [5]

Fig. 4.4 DA, DB, DC, DD and DE size connectors

4.4 RS-232

In telecommunications, RS-232 (Recommended Standard 232) is the traditional name for a

series of standards for serial binary single-ended data and control signals connecting

between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating

Equipment). It is commonly used in computer serial ports. The standard defines the

electrical characteristics and timing of signals, the meaning of signals, and the physical size

and pin out of connectors.

The current version of the standard is TIA-232-F Interface Between Data Terminal

Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data

Interchange, issued in 1997. An RS-232 port was once a standard feature of a personal

computer for connections to modems, printers, mice, data storage, un-interruptible power

23

supplies, and other peripheral devices. However, the limited transmission speed, relatively

large voltage swing, and large standard connectors motivated development of the universal

serial bus which has displaced RS-232 from most of its peripheral interface roles. Many

modern personal computers have no RS-232 ports and must use an external converter to

connect to older peripherals. Some RS-232 devices are still found especially in industrial

machines or scientific instruments. [5]

4.5 BAUD rate

In telecommunications and electronics, baud (/ˈbɔːd/, unit symbol "Bd") is synonymous to

symbols per second or pulses per second. It is the unit of symbol rate, also known as baud

rate or modulation rate; the number of distinct symbol changes (signaling events) made to

the transmission medium per second in a digitally modulated signal or a line code. The baud

rate is related to but should not be confused with gross bit rate expressed in bit/s.

A simple example: A baud rate of 1 kBd = 1,000 Bd is synonymous to a symbol rate

of 1,000 symbols per second. In case of a modem, this corresponds to 1,000 tones per

second, and in case of a line code, this corresponds to 1,000 pulses per second. The symbol

duration time is 1/1,000 second = 1 millisecond.

Of course, the common term baud rate is a misnomer since by definition baud is

pulses or switches per second and baud rate would be pulses or switches per second per

second or acceleration. The symbol duration time, also known as unit interval, can be

directly measured as the time between transitions by looking into an eye diagram of an

oscilloscope. The symbol duration time Ts can be calculated as:

Ts = 1 / fs, where fs is the symbol rate.

The baud unit is named after Émile Baudot, the inventor of the Baudot code for

telegraphy, and is represented as SI units. That is, the first letter of its symbol is uppercase

(Bd), but when the unit is spelled out, it should be written in lowercase (baud) except when

it begins a sentence.

Dedicated edges improve your emotional attachment to the graphics object and

ensure precise object manipulation in 3D space. The V-shaped cap particularly

supports the "zoom" command, the most commonly used positioning command in 3D

design applications. Optimised overall dimensions and generous device weight,

24

produce unsurpassed stability for hassle-free computing experience.In CAD/CAM, CAE

and visual simulation applications, the 3D Motion Controller is used in conjunction

with the normal mouse. As the user positions the 3D object with SpaceMouse®, the

necessity of going back and forth to a menu is eliminated.

Thus, drawing times can be reduced by 20-30%, increasing overall productivity.

Other benefits include an improved design comprehension and earlier detection of design

errors, contributing to faster time to market and cost savings in the design process. This

premium 3D motion controller features 11 programmable map keys (plus a

Quicktip® button) that let you easily customize the device's sensitivity settings and

motion controls. You also may assign application-specific tasks to the buttons. The

inclined keypad has nine buttons with two additional buttons on each side of the cap for

easy access. Its patented high-tech core, an opto-electronic and contact-less measuring

system provides six degrees of freedom motion control (X, Y, Z, pitch, roll and yaw)

without the need for calibration.

4.6 DLR control ball, Magellan's predecessor

At the end of the seventies, the DLR (German Aerospace Research Center) institute for

robotics and system dynamics started research on devices for the 6-dof control of robot

grippers .in Cartesian space. After lengthy experiments it turned out around 1981 that

integrating a six axis force torque sensor (3 force, 3 torque components) into a plastic

hollow ball was the optimal solution. Such a ball registered the linear and

rotationaldisplacements as generated by the forces/ torques of a human hand, which

were then computationally transformed into translational / rotational motion speeds. [1]

4.6.1 Force Torque sensor

Force torque sensors basically measure the linear and rotational displacement of the ball

containing the sensor arrangement.

Description of the individual components:

Transducer Cable: For our Nano and Mini transducer models, the transducer cable

is integral to the transducer. For other transducers the transducer cable is attached

with a connector. The transducer cable is a long-life flexible cable specially

designed for noise immunity. This durable cable protects the transducer signals from

electrical fields and mechanical stress.

25

Interface Board: The interface board electronics receive transducer strain gauge

signals and convert them to readable DAQ card signals using noise immunity

technology. Each interface board is calibrated to work with a specific transducer.

The interface board is mounted in the Gamma and larger transducer models and is

located in the Interface Power Supply Box (IFPS) for the Nano and Mini transducer

models. Output is uncalibrated. ATI software must be used to produce calibrated

output.

Power Supply: The power supply converts readily available five volt (275mA)

power from the PC through the DAQ card connection to clean power used by the

transducer. The power supply is mounted in a small box that connects to the

transducer cable on one end and to the data acquisition card on the other. When not

mounted on the transducer, the interface board electronics are included with the

power supply.

Power Supply Cable: The power supply cable conducts five volt power to the

power supply box or interface power supply box and transmits the transducer signals

to the data acquisition card. The cable has a flexible long-life design with special

noise immunity features.

Data Acquisition (DAQ) Card: The data acquisition card plugs into your PC,

receives the analog transducer signals via the power supply cable and (with ATI

software on your computer) converts them into data to be used by computer

programs. Our data acquisition cards are available in a wide variety of

configurations and supply power to the F/T system. In many cases, you can use an

existing data acquisition card.

The first force torque sensor used was based upon strain gauge technology,

integrated into a plastic hollow ball. DLR had the basic concept centre of a hollow

ball handle approximately coinciding with the measuring centre of an integrated 6 dof

force / torque sensor patented in Europe and US. From 1982-1985, the first prototype

applications showed that DLR's control ball was not only excellently suited as a

control device for robots, but also for the first 3D-graphics system that came onto

the market at that time. Wide commercial distribution was prevented by the high sales

price of about $8,000 per unit. It took until 1985 for the DLR's developer group to

succeed in designing a much cheaper optical measuring system.

26

Fig. 4.5 DLR control ball

4.6.2 Basic principle

The new system used 6 one-dimensional position detectors. This system received a

worldwide patent. The basic principle is as follows. The measuring system consists of an

inner and an outer part. The measuring arrangement in the inner ring is composed of the

LED, a slit and perpendicular to the slit on the opposite side of the ring a linear

position sensitive detector (PSD). The slit / LED combination is mobile against the

remaining system. Six such systems (rotated by 60 degrees each) are mounted in a plane,

whereby the slits alternatively are vertical and parallel to the plane. The ring with PSD's is

fixed inside the outer part and connected via springs with the LED-slit-basis. The springs

bring the inner part back to a neutral position when no forces / torque are exerted: There is a

particularly simple and unique. This measuring system is drift-free and not subject to aging

effects.

The whole electronics including computational processing on a one-chip-

processor was already integrable into the ball by means of two small double sided surface

mount device (SMD) boards, the manufacturing costs were reduced to below $1,000, but

the sales price still hovered in the area of $3,000. The original hopes of the developers

group that the license companies might be able to redevelop devices towards much

lower manufacturing costs did not materialize. On the other hand, with passing of

time, other technologically comparable ball systems appeared on the market especially

in USA. They differed only in the type of measuring system.

The present invention relates to an optoelectronic array or system housed in a plastic

sphere by means of which six displacement components can be simultaneously input.

These displacements consist, in a Cartesian system of coordinates, of displacements in the

27

X, Y and Z direction and regular rotations Dx, Dy, and Dz around the three axis. With the

use of this array or system, the programing of robotic movements or, generally

formulated, manipulator movements are quite easily, conveniently and quickly effected. In

3D graphic applications, on-screen projections may also be very rapidly shifted, rotated or

zoomed in on.

In order to measure, by means of the array, six different components,

specifically, three displacements in the direction of X, Y and Z axis of a Cartesian system

of coordinates and three angular rotations around these three axes, the LED with their

corresponding slit diaphragms are moveable with respect to the PSD. These PSD are

preferably arrayed on the inside of a cylindrical ring which is firmly attached to the inside

of plastic sphere. Between the ring bearing the PSD and the mounting device supporting at

its center the LED, provision is made for spring element, preferably in the form of coiled

springs, which are secured for example by screw bolts in such a way that the ring bearing

the PSD may move relative to the stationary mounting device with its six LED devices

and associated slit diaphragms in such a way that ring always returns to its original

position.

The objective is accomplished by means of an optoelectronic array or system housed

in a plastic sphere and having at least six light emitting devices equally displaced

angularly from each other and arrayed in a surface plane, together with correspondingly

aligned slit diaphragms allocated thereto. In addition, opposite each of the LED a linear

1D position sensitive detector is so displaced that it’s sensor axis is aligned vertically

relative to slit direction of the respective corresponding slit diaphragm.

Around 1990, terms like cyberspace and virtual reality became popular. However, the

effort required to steer oneself around in a virtual world using helmet and glove tires one

out quickly. Movements were measured by electromagnetic or ultrasonic means, with the

human head having problems in controlling translational speeds. The ring with PSD's is

fixed inside the outer part and connected via springs with the LED-slit-basis. In addition,

moving the hand around in free space leads to fairly fast fatigue. Thus a redesign of the ball

idea seemed urgent. In order to measure, by means of the array, six different components,

specifically, three displacements in the direction of X, Y and Z axis of a Cartesian system of

coordinates and three angular rotations around these three axes, the LED with their

corresponding slit diaphragms are moveable with respect to the PSD. These PSD are

28

preferably arrayed on the inside of a cylindrical ring which is firmly attached to the inside

of plastic sphere.

Fig. 4.6 Working of Space Mouse

4.6.3 Position Sensitive Device

A Position Sensitive Device and/or Position Sensitive Detector (PSD) is an optical position

sensor (OPS), that can measure a position of a light spot in one or two-dimensions on a

sensor surface. The technical term PSD was first used in a 1957 publication by J.T.

29

Wallmark for lateral photoelectric effect used for local measurements. On a laminar

semiconductor, a so-called PIN diode is exposed to a tiny spot of light. This exposure

causes a change in local resistance and thus electron flow in four electrodes. From the

currents Ia, Ib, Ic and Id in the electrodes, the location of the light spot is computed using

the following equations.

and

Fig. 4.7 Design of PSD using PIN Diode

The kx and ky are simple scaling factors, which permit transformation into coordinates.

An advantage of this process is the continuous measurement of the light spot position

with measuring rates up to over 100 kHz. The dependence of local measurement on form

and size of the light spot as well as the nonlinear connection are a disadvantage that can be

partly compensated by special electrode shapes. [9]

4.7 Magellan (the European Space mouse)

With the developments explained in the previous sections, DLR's development group

started a transfer company, SPACE CONTROL and addressed a clear goal: To

30

redesign the control ball idea with its unsurpassed optoelectronic measuring system

and optimize it thus that to reduce manufacturing costs to a fraction of its previous amount

and thus allow it to approach the pricing level of high quality PC mouse at least long-term.

The new manipulation device would also be able to function as a conventional mouse and

appear like one, yet maintain its versatility in a real workstation design environment.

The result of an intense one-year's work was the European Space Mouse, in the USA

it is especially in the European market place. But end of 93, DLR and SPACE CONTROL

jointly approached LOGITECH because of their wide expertise with pointing devices

for computers to market and sell Magellan in USA and Asia. The wear resistant and drift

free optoelectronic, 6 component measuring system was optimized to place all the

electronics, including the analogous signal processing, AT conversion, computational

evaluation and power supply on only one side of a tiny SMD- board inside Magellan's

handling cap.

It only needs a few milliamperes of current supplied through the serial port of any PC

or standard mouse interface. It does not need a dedicated power supply. The electronic

circuitry using a lot of time multiplex technology was simplified by a factor of five,

compared to the former control balls mentioned before. The unbelievably tedious

mechanical optimization, where the simple adjustment of the PSD's with respect to the

slits played a central role in its construction, finally led to 3 simple injection molding parts,

namely the basic housing, a cap handle with the measuring system inside and the small

nine button keyboard system. The housing, a punched steel plate provides Magellan with

the necessary weight for stability any kind of metal cutting was avoided.

The small board inside the cap (including a beeper) takes diverse mechanical

functions as well. For example, it contains the automatically mountable springs as well as

overload protection. The springs were optimized in the measuring system so that they no

longer show hysteresis; nevertheless different stiffness of the cap are realizable by

selection of appropriate springs. Ergonomically, Magellan was constructed as flat as can be

so that the human hand may rest on it without fatigue. Slight pressures of the fingers

on the cap of Magellan is sufficient for generating deflections in X, Y, and Z planes, thus

shifting a cursor or flying a 3D graphics object transnationally through space. Slight twists

of the cap cause rotational motions of a 3D graphics object around the corresponding axes.

Pulling the cap in the Z direction corresponds to zooming function. Moving the cap in

X or Y direction drags the horizontally and vertically respectively on the screen. Twisting

31

the cap over one of the main axes or any combination of them rotates the object

over the corresponding axis on the screen. The user can handle the object on the

screen a he were holding it in his own left hand and helping the right hand to undertake

the constructive actions on specific points lines or surfaces or simply by unconsciously

bringing to the front of appropriate perspective view of any necessary detail of the object.

With the integration of nine additional key buttons any macro functions can be mapped

onto one of the keys thus allowing the user most frequent function to be called by a

slight finger touch from the left hand.

The device has special features like dominant mode. It uses those degrees of freedom

in which the greatest magnitude is generated. So defined movements can be created.

Connection to the computer is through a 3m cable (DB9 female) and platform

adapter if necessary. Use of handshake signals (RTSSCTS) is recommended for the safe

operation of the space mouse. Without these handshake signals loss of data may occur.

Additional signal lines are provided to power the Magellan (DTS&RTS). Thus, no

additional power supply is needed. Flying an object in 6dof is done intuitively without any

strain.

In a similar way, flying oneself through a virtual world is just fun. Touching the keys

result in either the usual menu selection, mode selection or the pickup of 3D objects. Every

day of your computing life, you reach out for the mouse whenever you want to

move the cursor or activate something. The mouse senses your motion and your

clicks and sends them to the computer so it can respond appropriately. An ordinary

mouse detects motion in the X and Y plane and acts as a two dimensional controller. It is

not well suited for people to use in a 3D graphics environment.

Space Mouse is a professional 3D controller specifically designed for manipulating

objects in a 3D environment. It permits the simultaneous control of all six degrees of

freedom - translation rotation or a combination. . The device serves as an intuitiveman-

machine interface. The predecessor of the space mouse was the DLR controller ball. Space

mouse has its origins in the late seventies when the DLR (German Aerospace Research

Establishment) started research in its robotics and system dynamics division on devices with

six degrees of freedom (6 dof) for controlling robot grippers in Cartesian space. The basic

behind its construction is mechatronics engineering and the multisensory concept. The

space mouse has different modes of operation in which it can also be used as a two-

dimensional mouse.

32

Magellan/Space Mouse Classic is used in conjunction with the normal mouse (or

tablet). The user intuitively positions an object with Magellan/Space Mouse while working

on that object using the mouse. Slight pressure of the fingers onto the cap is sufficient for

generating small deflections of a 3D graphic object. This corresponds to the natural way of

executing coordinated operations with both hands and supports intuitive creativity without

interrupting the natural thought process. Additionally, the ergonomic design of a flat cap

reduces stress in the hand and arm. Magellan/Space Mouse 3D Motion Controller translates

your sense of touch into dynamic movement of objects within 3D space.

Fig. 4.8 How Space Mouse works

It’s patented high-tech core (license DLR), an optoelectronic and contactless measuring

system provides 6 degrees of freedom motion control (X, Y, Z, pitch, roll and yaw) without

the need for calibration. Magellan/Space Mouse technology has been optimized and

miniaturized in such a way that it works with standard serial interfaces without any

additional power supply. Magellan Space Mouse Classic is a space-proven, highly reliable

33

professional product, manufactured according to the strictest quality standards of Logitech,

the world Os leading manufacturer of control devices.

CHAPTER 5

BENEFITS, LIMITATIONS & FUTURE ASPECTS

5.1 Benefits

34

As the user positions the 3D objects with the Magellan device the necessity of going

back and forth to the menu is eliminated. Drawing times is reduced by 20%-30%

increasing overall productivity.

With the Magellan device improved design comprehension is possible and earlier

detection of design errors contributing faster time to market and cost savings

in the design process.

Any computer whose graphics power allows to update at least 5 frames per

second of the designed scenery, and which has a standard RS232 interface, can

make use of the full potential of Magellan space mouse.

In 3D applications Magellan is used in conjunction with a 2D mouse. The user

positions an object with space mouse while working on the object using a

mouse. We can consider it as a workman holding an object in his left hand and

working on it with a tool in his right hand.

Now Magellan space mouse is becoming something for standard input device

for interactive motion control of 3D graphics objects in its working environment

and for many other applications.

5.2 Limitations

System based on any processor after Intel Pentium4 is required.

10 Megabytes free disk space is required for driver and plug-in installation (CD-

ROM device required).

USB 1.1 or greater (USB only) is required.

5.3 Features

Ease of use of manipulating objects in 3D applications.

Calibration free sensor technology for high precision and unique reliability.

Nine programmable buttons to customize users preference for motion control

Fingertip operation for maximum precision and performance.

Settings to adjust sensitivity and motion control to the users preference.

Small form factor frees up the desk space.

Double productivity of object manipulation in 3D applications.

Natural hand position (resting on table) eliminates fatigue.

35

5.4 Future Aspects

Magellan's predecessor, DLR's control ball, was a key element of the first real robot in

space, ROTEX- (3), which was launched in April 93 with space shuttle COLUMBIA inside

a rack of the spacelab-D2. The robot was directly tele-operated by the astronauts using

the control ball, the same way remotely controlled from ground (on-line and off line)

implying "predictive" stereo graphics. As an example, the ground operator with one of the

two balls or Magellan’s steered the robot's gripper in the graphics presimulation,

while with the second device he was able to move the whole scenery around

smoothly in 6 dot Predictive graphics simulation together with the above mentioned

man machine interaction allowed for the compensation of overall signal delays up to

seven seconds, the most spectacular accomplishment being the grasping of a floating

object in space from the ground. Since then, ROTEX has often been declared as the first

real "virtual reality" application.

SPACE MOUSE "Plus" is the newest award-winning product in the line of

professional 3D motion controllers for industrial design and visual simulation

applications. It provides intuitive and precise interactive motion control of three-

dimensional graphic objects in up to six degrees of freedom simultaneously. This

professional input device dramatically increases productivity, improves object

comprehension and helps detect design errors earlier. A new, user-friendly cap with a

distinctive grip area for thumb, forefinger and middle finger supports virtually every

single cap movement with the uniquely soft, pressure-sensitive sensor. Dedicated

edges improve your emotional attachment to the graphics object and ensure precise

object manipulation in 3D space.

The V-shaped cap particularly supports the “zoom” command, the most

commonly used positioning command in 3D design applications. Optimized overall

dimensions and generous device weight, produce unsurpassed stability for hassle-free

computing experience. This premium 3D motion controller features 11 programmable

map keys that let you easily customize the device’s sensitivity settings and motion

controls. You also may assign application-specific tasks to the buttons. The inclined keypad

has nine buttons with two additional buttons on each side of the cap for easy access. Its

patented high-tech core, an opto-electronic and contact-less measuring system provides

six degrees of freedom motion control (X, Y, Z, pitch, roll and yaw) without the need for

calibration.

36

5.4.1 Visual Space Mouse

In many areas of our daily life we are faced with rather complex tasks that have to

be done in circumstances unfavorable for human beings. For example, heavy weights

may have to be lifted or the environment may be dangerous and, therefore, the

assistance of a machine is needed. Some of these tasks, on the other hand, also need the

presence of a human, because the complexity of the task is beyond the capability that

an independent robot system is able to handle. Therefore, there is a need for a robot system

controlled by a human.

A most intuitive controlling device would be a system that can be instructed by

watching and imitating the human user, using the hand as the major controlling

element. This would be a very comfortable interface that allows the user to move a

robot system in the most natural way. This is called the visual space mouse. The system of

the visual space mouse can be divided into two main parts: image processing and

robot control. The role of image processing is to perform operations on a video signal,

received by a video camera, to extract desired information out of the video signal. The

role of robot control is to transform electronic commands into movements of the

manipulator.

A most intuitive controlling device would be a system that can beinstructed by

watching and imitating the human user, using the hand as the major controlling element.

This would be a very comfortable interface that allows the user to move a robot system

in the most natural way. This is called the visual space mouse. The system of the

visual space mouse can be divided into two main parts: image processing and robot

control. The role of image processing is to perform operations on a video signal, received

by a video camera, to extract desired information out of the video signal. The role

of robot control is to transform electronic commands into movements of the

manipulator. The purpose of this project was to develop a system that is able to control a

robotic system by observing the human and directly converting hand gestures into

movements of the manipulator.

37

Fig. 5.1 Visual Space Mouse

The hand serves as the primary controlling element to effect the actual motion

and position of a robot gripper. For the observation of the user, one usual greyscale

camera is used without any kind of calibration. The manipulator is a PUMA 560 robot with

six degrees of freedom and a gripper. We use the image processing language VEIL for

image processings. A special feature of VEIL is blobs. These are defined as a brighter

region in the image plane within a darker environment. The hand is detected and

traced with the help of blobs. This blob contains the characteristic values of the image of

the hand. The values of the blob are then passed to the control part of the program to

affect the actual position of the manipulator.

38

CHAPTER 6

CONCLUSION

The graphics simulation and manipulation of 3D volume objects and virtual worlds

and their combination e.g. with real information as contained in TV images (multi-media) is

not only meaningful for space technology, but will strongly change the whole world of

manufacturing and construction technology, including other areas like urban development,

chemistry, biology, and entertainment. For all these applications we believe there is no other

man- machine interface technology comparable to Magellan in its simplicity and yet high

precision. It is used for 3D manipulations in 6 dof, but at the same time may function as a

conventional 2D mouse.

39

REFERENCES

Websites:

[1] http://seminarprojects.com/s/space-mouse

[2] http://www.3dconnexion.com/history.html

[3] http://en.wikipedia.org/wiki/Six_degrees_of_freedom

[4] http://www.dlr.de/rm/en/desktopdefault.aspx/tabid-3808/6234_read-8998/

[5] http://en.wikipedia.org/wiki/D-subminiature

[6] http://en.wikipedia.org/wiki/Mechatronics

[7] http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA427920

[8] http://spacecontrol.de/index.php?id=25&L=2

[9] http://en.wikipedia.org/wiki/Position_sensitive_device

40