Robotic Arm and Dexterous Hand
Critical Design ReviewFebruary 18, 2005
The Team
DavidParrett
Wen JiaWang
KenPeters
JustinTubiolo
JeremyAmidon
Overview
Needs and Objectives Requirements and SpecificationsDesign Analysis and Synthesis
User Input Device Mechanical Operation Mechanical Power PC and Microcontroller Programs Electrical Output Circuit
Feasibility AssessmentFuture Plans
Schedule and Budget
Project Needs & Objectives
Maximum exhibit life span and durability.
Intuitive navigation and operation by users.
Robotics theme an exceptionally inviting "attractor factor."
Accessibility to many users of different age and physical ability.
Provide maintenance information and details.
The robotics exhibit becomes an extension of the human arm.
Test the display in its target environment to ensure success.
Project Specifications
The Input Device detects four movements of the hand and the fingers
The Robotic Arm moves with 4 large muscles The wrist operates as a hinge, moving the hand up and down approx. 45o
The elbow operates as a hinge, moving the hand and arm up and down approx. 45o
The shoulder rotates the entire arm around approx 180o
The upper arm lengthens and contracts a distance of at least 1 foot (0.3 m)
The Robotic Hand contains five fingers, 4 of which can move separately The thumb, index, and pinky fingers are able to move separately The middle and ring fingers move together The fingertips contract from open position to 90o partly closed
Design Analysis
User Input Device
Mechanical Operation
Mechanical Power
PC and Microcontroller Program
Electrical Output Circuit
Concept Block DiagramGlove Controller
Personal Computer
Microcontroller
Extension CylinderRotational Motor
Limiting Sensor Air Valves
Air MuscleTable Touch Sensor
Movement Cables
Air Pressure Supply
Wrist Joint Elbow JointFinger Joints
User Input Device
Sensor Laced Glove & Fighter Joystick
Utilize Flex Sensors in the Glove
Sensor Glove with Motion Track Glove has Flex Sensors in the Fingers Infrared Receptor Senses Motion in 6 Degrees
Courtesy of http://devices.sapp.org/component/flex/
P5 Data Glove
Courtesy of Essential Reality
Arm Concept
Arm With Wrist, Elbow & Rotating Cylinder 4 Degrees of Freedom Maximum Reach
Mechanical Power
Power Source Concepts
Electric 24 Volt DC Motors For the cylinder a high speed
and high current DC Servo Motor is used
For the rotation of the arm a motor with a gearbox is used for higher torque and slower speed
Power Source Concepts
Pneumatics Utilize air muscles Power-to-Weight Ratio up to 400:1 Apply Forces up to 140 lbs. Very Flexible
Photo courtesy of Shadow Robot Company
Pneumatics
Air muscles are controlled by 24 volt solenoid valves
Valve Lifespan
Valves are rated for 200 million cyclesValve Lifespan
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
0 50 100 150 200 250
Cycles Per Minute
Yea
rs
Finger Curl Problem
Linear motion of muscles was inadequate
Design Images
Design Pictures
Project Pictures
Electrical Input/Output
Inputs to PC USB signal from glove controller
Output from PC RS-232 serial output to MDB
Inputs to MDB Serial input to the UART from the PC Magnetic field sensors from arm cylinder and rotating gear Touch sensor to detect when the hand touches the display table
Output from MDB Digital signal to each valve to control pressure in air muscle Extension cylinder motor control lines
Serial port
9 PIN RS-232 serial port is used to send motion control data to the microprocessor
Serial Port Encoding
Motion ID bit 3
Motion ID bit 2
Motion ID bit 1
Speed bit 1
Speed bit 2
Speed bit 3
Speed bit 4
Direction
bit
7 6 5 4 3 2 1 0
Bit Value Motion ID
000 Thumb
001 Index
010 Middle Or Ring
011 Pinky
100 Elbow
101 Wrist
110 Up/Down
111 Left/Right
Each clock cycle the serial port transfers 8 bits of data:
Bit Valu
eSpeed
00000 stop
00010 reverse
00011 forward
8051 Development Kit
Control Concept
Arm Motion Control When the glove is moving, then the arm moves in the
same direction controlled by these signals from the glove: ‘x’ Axis controls rotional motor ‘y’ Axis controls elbow motion ‘z’ Axis controls extension cylinder ‘pitch’ Axis controls the wrist motion
Finger Motion Control Motion control theory for the fingers is same as for the arm Each robotic finger is controlled by each finger sensor on
the glove
PC Program
Initialize the P5 GloveInitialize the Serial PortBegin Main Loop Update Glove Variables with current data Filter Incoming Data to detect motion above
a certain threshold Convert Filtered Data to an 8-bit serial output Send output byte to the serial port Loop forever
Microprocessor Program
Setup the UART for serial transmission with interruptsSetup the ports for correct I/OBegin Main Loop Look at the most recent incoming serial
data Check the first 3 bits for motion ID Check the last 2 bits for desired motion If the sensor feedback allows this motion,
execute this motion and send output to port Loop forever
Theoretical Power Circuit
24V DC
BJT
microprocessor
3V DCLED 1.8K omes
RelayMotors
Control CircuitFan resister
Out put from BJT(3V)
Input from microprocessor
Motor control relays
Air musclevalves
Control relays
Connect to motor
Power switches
Connect to Motor(24V)
Low Signal Relay
Max. operating voltage 125 VAC, 60 VDC carry current 1 ARated voltage (VDC) 3Rated current (mA) 33.0Coil resistance (Ω) 91
BJT AMP board Input from microprocessor
(3.3V 25mA)
Output to relays (3v 50mA)
Power supply
Voltage output of 24 V
Maximum current of 2.5 A
Over voltage protection
Over current protection
Final Circuits
Controlcircuit
BJTboard
PowerSupply
(24V 5A)Microprocessor
Output to air valves and motors
Schedule
Cost Worksheetpart Quantity Unit cost Estimated Cost Actual Cost
Sensor Gloves 1 $80 $80 $30
Air Muscles large 5 $50 $250 $250
Air Muscles small 6 $26 $26 $156
Valve Manifold 1 $160 $160 $160
Valves 4 $70 $280 $280
Regulator 2 $50 $100 $100
Air Line 3 $15 $45 $45
High Tensile String 1 $12 $12 $12
Ait Filter 1 $75 $75 $75
Hand and Forearm 1 $500 $500 $383
Electric Cylinder 1 $200 $200 $65
Enclosure/Display 1 $1,000 $1,000 $450
Microcontroller 1 $200 $200 $180
PC 1 $400 $400 $0
Electric circlts 1 $400 $400 $559
Total $3,238 $3,728 $2,745
Video Demo
Questions?