Android Processing Arduino: Use Android smartphone to control two wheels robot with Arduino via Bluetooth

1) Mechanical parts: Make your own two wheels robot!

If you still don't have a two wheels robot, you can try to make one with the components below:

(This components are used in my own robots, you can change it as you like.)

2 pieces of perspek
4 PCB stand
Servo motor
2 gear motors
1 H-Bridge for two motor for two way controlling
2 wheels
Small size breadboard
Bluetooth Receiver Module
Arduino Leonardo
1 piece of 9V battery
Battery holder
Rechargeable batteries (2500mAh)

Below are the process of making of my own two wheels robot:

Stage 1

The first prototype of our robot is constructed in a way that the body of the robot is made out of red plastic cardboard due to the benefits of its material that is light enabling the robot to go at a higher pace. Then two 3.3V DC tamiya motor are being used to be built as a part of the wheels of our robot. These wheels are being used as they could produce speed up to 18000rpm. But after testing we found out that Tamiya motor has very low torque. When there are some loads on the motor it will not move at all. At this stage we are still thinking of the Pulse wave modulation (PWM) problem. Another testing will be done on Tamiya motor later. As all the component (servo motor, 2 tamiya motor, arduino, battery and etc) are being constructed onto our robot, the plastic cardboard that was used as the body of the robot could not withstand the amount of weight and it was squashed.

Stage 2

This is the second prototype of our robot where the body is being built using perspek. As the red plastic board couldn’t withstand the weight of the components placed, another material was being used as the body of the robot. Due to the replacement of a new material as the body of the robot to sustain more weight, the material seem to withstand the amount of mass withstand on it but unfortunately it causes the robot to move at a slower pace due to the mass of perspek is slightly higher than to a plastic cardboard. Later on we found out that when we send the PWM pulse into the 3.3V tamiya motor via transistor from Arduino, it really has a very low torque even with high voltage power supply and full PWM pulses(255).The motor can’t move with any load so it wasn’t suitable to be used in our mini project anymore.

Stage 3

12V DC motors

Since 3.3V tamiya DC motors aren’t suitable to be used in the construction of our robot, it was replaced by a 12V DC motor instead. This replacement produces higher torque but still the speed is low hence sufficient voltage needed to be supplied in order for the robot to move faster. But this affects the total weight of the robot as the weight increases with the increase in voltage due to more amounts of batteries were being used. Besides that, our robot design was enhanced by making a few extra changes to it such as metal strips are being used to hold both the motor in place, In prevention of short circuit, this metal strips were insulated by covering it with heat tube.

Stage 4

Gear motor

As we found out that 12V DC motor are also aren’t suitable to be used in the construction of our robot, it was replaced by a pair of 6V gear motors. Gear motor can produce higher torque hence enabling the robot to actually move faster to be compared to previous prototype. This gear motor we bought comes with stall torque 0.3kg/cm and 440 free run rpm.Also, the weight of each gear motor only 10 gram as this will make the total weight of the robot a lot lighter so that it can run faster. The detail of the gear motor can be viewed on the link below: http://www.cytron.com.my/viewProduct.php?pcode=SPG10-30K&name=30:1%20Micro%20Metal%20Gearmotor

Upper view of the robot

Back view of the robot

Side view of the robot

Bottom view of the robot(with a caster at lower middle part)

Moreover, we found out that short circuit may be occurred due to limited space to place these components on top of the robot, so we enhance the design of the robot by using a PCB stand to hold another layer of perspek. With this, we have enough space to place these components neatly in prevention of short circuit. Moreover, we changed the actuator design of the robot into a smaller piece of metal as it’s smaller and suitable to be used for the soccer game competition. To enable the robot to move faster, we used high amp rechargeable battery (2500mAh). With this, the gear motor can perform well as expected when all the component are placed on the robot.