Chapter One : Introduction1

1.1 Statement of the problem:- This project is to design a special vehicle that transforming to quadpod which is four leg walking robot. The purpose is to overcome obstacles that car cannot go through.

1.2 Objectives:- We believe this project is important because this scaled version of vehicle can access places (mountain and bumpy roads) that the vehicle cannot get through with typical wheels. This project merely shows the basic concept of the transformable vehicle but it may help the vehicle to be used in more various situations in the future. The main goal is to make a miniature vehicle that can be transformed into the Quadpod, the vehicle with four legs, when it meets an obstacle that can't be overcome with typical wheels. The obstacle could be any place difficult to move by vehicle but we're mainly focusing on rough unpaved road or hill. The project will consist 4 legs (2 on each side), which will only be activated when the vehicle is in “Quadpod” mode and use it to overcome obstacle.

1.3 Scope of the work:- Our project mainly focus on transforming from vehicle mode to quadpod mode and how to keep the project balanced in both modes. The project can be used in many ways like moving on rough roads, hills, and forests. It also can be used in hard situations like in a fire incident to search for people inside the building without the need for humans to get inside (this can be done by adding a camera to the robot).

1.4 Benefits:- - Vehicle can overcome obstacles such as bumpy road, mountain, jungle and forest, which typical car can't get through.

- The vehicle can sense obstacles by using touch sensor in the bumper so that it can automatically transform.

- Both car mode and Quadpod mode are fully controllable by user interface.

- Multifunctional vehicle for multipurpose use.

- Forcefully transformable when driver desires.

1.5 Organization:- We organized the project in the way the ABET asked for as follow, we started with the introduction as the first chapter to talk about the project briefly. Then, for the second chapter we added the constrains and code/standards related to the project. After that we wrote the literature review as the third chapter which talk about some paper and research we did about our project. Then the fourth chapter was the methodology which we talked about the project in details and showed what components we are using for our project . then we summarized all the collected data in the fifth chapter under the results and analysis

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subject. Then in the sixth chapter we discussed subjects about the project briefly. Finally, in the seventh chapter we wrote the conclusion about our project.

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Chapter Two: Constrains , Standards/Codes and Earlier Course work

2.1 Constrains:-

We faced several problems in the project for example : Dealing with the Autocad .

Overcome : We have to solve this problem by learning the program and get help from graduate electrical engineers in order to learn it .

Calculating the center of mass

Overcome : We got help from Mechanic & Mechatronics teachers .

Buy the components needed for the project.

Overcome : We bought the component through internet but the shipping will take time .

the legs have enough strength to lift up the whole vehicle.Overcome : We did some calculations shown later on .

2.2 Standards/Codes:- We have implemented our project according to:

1- National Electrical Safety Code (NESC)2- IEC (International Electrotechnical commission) standards3- BS EN 61000-6-3,4 (Electromagnetic compatibility, Generic emission standard4- BS EN 1127, parts1,2 (Explosive atmospheres, Explosion prevention and protection)5- BS EN ISO 12100 (Safety of machinery, General principles for design, Risk assessment

and Risk reduction)

2.3 Earlier coursework:-We took many courses that are related to our project , such as:

1- Control systems 2- Electrical machinery 3- Control of electrical machinery (Drive) 4- Analysis systems and signals 5- Electrical circuits 6- Electronic circuits 7- Electrical measurements and sensors 8- Micro processers and controllers.

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Chapter Three: Literature Review We have read some works related to our project on the internet , we mostly depended on videos to learn more about what we want. We mainly used Wikipedia.org ,Youtube.com ,Google.com , Letsmakerobots.com and Lynxmotion.net to get resources.

Going through these websites gave us more clear ideas about what is required for our project , which helped us to benefit from other experiences to avoid some problems with our design.

We also had a look on the robotics subject in the Mechatronics engineering department in our university which helped us to understand some concepts about robots and its simulation.

Let us now consider some of our research work ; we have seen many videos on YouTube about the robots . we have seen many types of robots with different number of legs , also many videos were actually very useful because they have considered the movement of the single leg of the robot very clearly which makes the condition more obvious to us .

We also took a look on some datasheets related to our project components such as the Arduino Mega , Sharp IR sensor , and mechanical characteristics of the push button for the legs' sensor .

we have also read about the legs' design of the robot .

also it took a lot of time to understand how to keep the balance of the robot , using the center of mass concept .

As for examples on other projects; there was some using ready kit for a close project to ours so we used it to learn more about the legs joint and balancing.

And there was another project that has the micro-controller design as main station, each leg has two degrees of freedom (DOF). And in the end of the project it gave a suggestion for motors type.

With these two projects and other similar projects we designed our robot schematic (refer to Appendix A).

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Chapter Four: Methodology

4.1 Block Diagram and Functions

Fig. 1: Block Diagram

- Main station (Arduino Mega): The microprocessor that gets signal from the wireless remote controller and control all of the vehicle's motors. Also, it receive the signal from the sensor and evaluate.

- Wheel movement system: This system controls wheels movement. There is two continuous rotation motors on each wheels. By changing pulse width, speed and direction can be controlled.

- Leg movement system: This system controls leg movement. There are two standard motors on each leg. Each controls X-axis and Y-axis of the leg. By changing pulse width, we can make the motor to turns to certain angle.

- Sensor control system: This system controls sensors. Sensors on bumper controls transforming and sensors on legs controls the movement of leg.

- User control system: This system send signal from the user to the main station to control the vehicles. There is 7 different serial data from the user interface and each commends different motions.

- Power: The power for the Arduino Mega is supplied by 9V battery, and two 7.4 Lipo batteries will supply the power for 5 motors each.

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4.2 Schematics:- While the project is in vehicle mode, it can go forward, left, right depends on the signal received by IR receiver. It can also transform into quadpod depend on the signal received from proximity sensor and the IR receiver. The Right and left Wheel motors are continuous rotation motor and they are in charge of controlling movement of the vehicle, while the 4 vertical movement motors are standard servo motors and they are in charge of transformation. All the motors are controlled with the length of the pulse given by the main station; thus, the motors are connected to the PWM output of the main station. While the project is in quadpod mode, it can go forward, turn left, turn right depends on the signal received by IR receiver. All these operations are done using the 8 standard servo motor, where 4 of them are in charge of vertical movement of legs and 4 in charge of horizontal movement. Again, all the motors are controlled with the length of the pulse given by the main station; thus, the motors are connected to the PWM output of the main station. The schematic is attached on the Appendix A.

4.3 Flow Charts:- During the semester, we gathered and made flow chart (refer to Appendix F) for vehicle mode and Quadpod mode of the project. The flow chart on Appendix F is the flow chart for vehicle mode we made during that time. Based on the flow chart, while the project is in vehicle mode, it can go forward, left, right, and backward depends on the signal received by IR receiver. It can also transform into Quadpod depend on the signal received from proximity sensor and the IR receiver. The continuous rotation motor are in charge of controlling movement of the vehicle

The same time we made flow chart for vehicle mode, we also made flow chart for Quadpod mode(refer to Appendix F). While the project is in Quadpod mode, it can go forward, go backward, turn left, turn right depends on the signal received by IR receiver. All these operations are done using the 8 standard servo motor, where 4 of them are in charge of vertical movement of legs and 4 in charge of horizontal movement

All the motors are controlled with the length of the pulse given by the main station; thus, the motors are connected to the PWM output of the main station.

We also did a simulation for the project design using AutoCAD (Appendix D,E) and also tried using some animation programs to show it movement refer to Appendix E.

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4.4 Detailed Descriptions:-

4.4.1 Main Station

Fig. 2: Arduino Mega 2560

Arduino Mega is the main station for the design. It should receive the signal from remote controller and generate pulse signal for the control of the motors. Arduino Mega recommended voltage is 7~12V, so we will use a 9V battery to help better performance, which is regulated to 5Vby the regulator installed inside Arduino Mega. The Arduino Mega should have a capability of supporting synchronized signal to all components connected to it.

On the station, the IR receiver for the remote controlling will be connected to 5V output voltage pin, and all the buttons for the sensing purpose are connected to digital input for the code controlling the whole vehicle. The PWM I/O pin will be linked to all the motors to give pulse signals with desired length for each motor rotation. All servo motors should work in the range of pulse width of (750us ~ 2250us2) and Arduino Mega can provide these pulses from the PWM output.

PulseMax= 16Mhz > PulseMotors

The current capacity on DC I/O pin is 40mA, which is in the effective current range of the IR receiver and the buttons. We can test the current value from I/O pin of Arduino Mega using resistor and some calculations. First, we connect resistor at I/O pin and Measure voltage across the resistor with voltage meter. Then we will be able to calculate the current coming

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out from the Arduino using the following equation. VR/R = I main = 40mA (with 5% error, Estimation) .

PMain = 20mA × 5V = 100mW

By using 9V battery which contains 550mAh

Max operating Hours: 550mA × 3600Sec / 100m = 19800sec = 5.5 hours

4.4.2 Motor Module

Continuous Motors

Fig. 3: Continuous Rotation Servo Motor

Two continuous rotation servo motors are used for the vehicle mode, it will simply function as wheels. The motors are powered up by the 7.4V 2-cell lithium battery and receive the pulse signal from Arduino Mega. The pulse length for rotating motors is different from the standard servo motor. It has three motions: turning clockwise, counter clockwise, and stop. Each motion is determined by a specific pulse length as shown in fig.4.

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Fig. 4: Continuous Servo Motor Pulses

Standard Servo Motors

Fig. 5: Standard Servo Motor

Eight servo motors are used for the quadpod mode. It's position is determined by a specific pulse length as shown in fig.6.

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Fig. 6: Standard Servo Motor Pulses

The motors are divided in two groups , one for the X-axis movement and the other for the Y-axis movement; as follows:

Standard Servo Motors (X-axis)The 4 standard servo motors are used for each leg moving x-axis for the Quadpod mode. The 7.4V 2-cell lithium battery powers up the motors with voltage regulator for the input voltage for the motors. The rotation angle of the standard servo motor depends on the input signal pulse length, sent by Arduino Mega. The input pulse length is between 750μs and 2250μs, which is corresponding to the whole 180° angle movement of the motor. This motor need repeated pulse signals at least every 20ms or faster to maintain its position. The degree from 45° to 135° will be used. The angle will be calculated with the following equation:

T (us)= 750us + {1500us (θ/180)} (45°< θ <135°) Standard Servo Motors (Y-axis)

The other 4 standard servo motors are used for each leg moving y-axis for the Quadpod mode. These y-axis motors are responsible for transforming between the vehicle mode and the Quadpod mode and the y-axis leg moving. Specifically, when it transforms from the vehicle mode to the Quadpod mode, the lifted legs will be brought down to the ground; the reverse transformation will make the legs to move the opposite way. The rest specifications are the same as x-axis standard servo motors except for the degree range (0°< θ <180°)2).

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Fig. 7: Standard servo motor rotation degree

4.4.3 Power Module

9V battery

One 9V batter is used only to power up the main station whose recommendation input voltage range is 7~12V.

Main station power source: Voltage = 9V

Capacity = 550mAh

7.4V Lithium battery

Six lithium 7.4V Batteries power up the servo motors. 5V voltage regulator is used to make the voltage down to 5V. This voltage regulator should be capable to endure all of the current flow to the motors.

Servo motors power supply:

Voltage = 5V

Capacity =2000mAh

Max continuous current = 20A

Power consumption by one motor = 190mA

8*Imotor = 1.5A

4.4.4 Voltage Regulators The input voltage to operate the motors is 4~6 VDC. The voltage regulators for each Lithium battery make the 7.4 volts down to 5 volts for the motors.

Input voltage: 7.4V

Max Input current: 190mA X 8 = 1.5A

Voltage regulator output voltage = 5V

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Voltage regulator max current output = 1.5A

4.4.5 IR receiver Takes serial data from the remote transmitter and sends it to the main station. The original commend inside remote controller will not be used. Instead, we will code our own commends. There are 7 different commend and each will be different signal so that the signal will not messed up with each other's. This device need 2.5 to 5.5V to power up and it needs at least 5mA source to activate. Since our Arduino provide 40mA with 5V, it will be reliable to fully function.

let’s overview each of the components in the IR Control Kit:

IR LED

Let’s start with simplest of the components first – the infrared LED. Anyone who’s ever worked with electronics has blinked an LED, but those blinking LEDs are usually in our visual spectrum. These IR LEDs are just like any LED you’ve blinked before, but they emit light at a wavelength of about 950nm – radiation well outside of our visual range (about 390 to 700nm).

Fig. 8: IR LED

You can’t see these LEDs light up, but you can still use them just like any LED. They still have two polarized legs: an anode (positive, the long leg) and a cathode. They have a typical forward voltage of about 1.5V, and a maximum forward current of 50mA.

330Ω Current Limiting Resistor

Just as with any LED, the IR LED needs a series resistor to limit current. That’s what the included 330Ω resistors are for.

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Fig. 9: 330Ω Resistor

With a 5V supply connected to the resistor/LED series combo, current through the LED should be limited to about 10mA, which is well inside its safe operating range.

TSOP38238 IR Receiver Module

While it may look like a simple transistor, the TSOP38238 IR receiver module is actually a unique, light-demodulating integrated circuit. With three pins, it’s about as simple as an IC can get. There are two pins for power – ground in the middle, and VS to a side – and one, single data output pin.

Fig. 10: TSOP38238 IR receiver

The IR receiver can be powered at anywhere from 2.5V to 5.5V, so it plays very nicely with a variety of development boards.

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This module is tuned to demodulate 38kHz signals, which are a very common in the IR signal world. It turns a spiky, modulated signal like this:

Fig. 11: Modulated Signal

Into this a cleaner, much easier to read signal like this:

Fig. 12: Demodulated Signal

So all we have to do to read the output of this device is count high and low pulses, and measure their durations.

IR Remote

Finally we come to the flashy part of the kit: SparkFun’s custom-made Infrared Remote Control. This nine button remote emits unique 32-bit codes for each button press. The codes are mapped as shown on this image (this will come in handy in our first example):

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Fig. 13: Code Scheme for Remote

The remote’s infrared output signal is modulated at 38kHz, so it works perfectly with the IR receiver module.

4.4.6 Sensors

Bumper Sensor

Fig. 14: Sharp GP2Y0A21YK Sensor

We used the Sharp IR Sensor as a bumper sensor , which is a distance measuring sensor unit, composed of an integrated combination of PSD (position sensitive detector) , IRED (infrared emitting diode) and signal processing circuit. The variety of the reflectivity of the object, the environmental temperature and the operating duration are not influenced easily to the distance detection because of adopting the triangulation method.

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The basis for triangulation is that objects at different distances will reflect the infrared beam back to the receiver at different angles. The varying angles produce different voltage levels in the sensor, and in turn sensor values that can be used to calculate distance. See fig. 4 and fig. 5.

Fig. 15: Triangulation effect

Fig. 16: Triangulation effect

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4.4.7 Mechanical Design The detailed design for the mechanical parts is on the Appendix B.

For the real model of the project refer to Appendix C.

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Chapter Five: Results and Analysis

5.1: Center of Mass We estimated the weight of each component in our project and it is appear as shown in below:

Arduino =40gm

Each motor =44gm

Continuous motor =40gm

Total mass of motors=(8*44)+(2*40) =432gm

Weight With battery and without arduino and without frame well be 553g

Weight With battery and with arduino and without frame well be 593g

We reached to a conclusion that there's two techniques to find the center of mass , one is theoretical and the other is practical. And they're discussed below:

Theoretically:

To find the center of mass to this robot , we will use the following equation:

x=∑mi∗xi∑mi

x:Center of mass.xi: the x-axis coordinates .mi: components mass .

Fig. 17: Center of Mass Concept

Practically

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The experimental determination of the center of mass of a body uses gravity forces on the body and relies on the fact that in the parallel gravity field near the surface of the earth the center of mass is the same as the center of gravity.

The center of mass of a body with an axis of symmetry and constant density must lie on this axis. Thus, the center of mass of a circular cylinder of constant density has its center of mass on the axis of the cylinder. In the same way, the center of mass of a spherically symmetric body of constant density is at the center of the sphere. In general, for any symmetry of a body, its center of mass will be a fixed point of that symmetry

Fig. 18: Center of Mass

5.2: Components Test

5.2.1 IR receiver Test: We tested the IR kit using the arduino mega and the example code in the kit guide and connected it as shown in Fig.19. For the code refer to Appendix G.1 and Appendix E.

Fig. 19: Connection of IR

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For our project, we built our own code for the IR kit as shown in Appendix G.2 . And we got the following result when we tested the code.

Fig. 20: Results of the code test

5.2.2 Motors Test :

5.2.2.1 Continuous Rotation Motor Test

We tested the motor using the arduino mega and the example code in the guide and connected it as shown in Fig.21. For the code refer to Appendix G.3 and Appendix E.

Fig. 21: Connection of motor

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5.2.2.2 Standard Servo Motor Test

We tested the motor using the arduino mega and the example code in the guide and connected it as shown in Fig.22. For the code refer to Appendix G.4.

Fig. 22: Connection of motor

5.2.3 Bumper Sensor Test :We tested the sensor using the arduino mega and the example code in the guide and connected it as shown in Fig.23. For the code refer to Appendix G.6.

Fig. 23: Connection of sensor

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Chapter Six: DiscussionIn our project ,We supposed that the robot will move leg after leg, but we have founded that our proposition leads to unbalanced situation cause of the change in the center of mass, so we have searched about something more reliable and acceptable which was getting an obstacle connected to a motor that move in the opposite way of the used motor and when the device is standing this obstacle is at the center of mass which we assume it to be at the middle of the robot.

As for the sensor at first, we thought that "The Proximity Touch Sensor" will be a good choice but after that we decided to use "The Sharp IR Sensor" which detect the obstacle from a distance of 10 to 80 cm according to the data sheet which is more reliable.

After the components test , we connected the components together to get the final form of the project as shown in Appendix C.

Then we wrote the final code of the project (shown in Appendix G.5) ,and when we sent it to the arduino we got some errors in the angle of the leg motors so we used trial and error along with previous projects example from the net like spider robot to get the right angles for the leg movements.

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Chapter Seven : Conclusion and Recommendation Through our work over the course of semester, we have successfully designed the schematic of a vehicle that can transform into quad pod. The project we designed is fully controllable by user in both quad pod mode and vehicle mode. User can control the movement of the project using the IR remote controller. The project also has obstacle sensor that automatically detects obstacle sends signal to transform the vehicle to Quadpod.

Many of the uncertainties come from mechanical issues such as frame design, durability, and weight. As our studies lead us that if the project doesn't have frame work that fixes the leg to the side of the body while it's in vehicle mode, the quad pod legs have to be fixed at 90 deg position by giving the pulse signal to avoid it touching the floor. This not only takes unnecessary space, but it also consumes extra energy that could otherwise be conserved. In order to have more efficient frame design, we would need larger body frame and additional frame that would fix the legs in certain position while it's in vehicle mode. However, larger body frame would cause the durability of frame to decrease while increasing the weight of the project.

As we have mentioned in challenges, one of the main issue we have to improve for future work is frame design. Our current frame design is inefficient in both space and power consumption. By creating frame design that holds the position of the legs while the project is in vehicle mode, it will save both space and power consumption. Improved frame design will probably increase the weight of the project. So we need to pay attention to the servo working torque according to the weight.

We are trying to create new type of vehicle with simple design in regards of the practical usage. We are open to accept any honest criticism regarding technical issues by admitting our lack of knowledge for better and practical design and technical work. As we use some parts that are already made by a company, we must give a full credit to the company by mentioning their name and work in proper manner.

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