two wheel balancing robot -mechanical design

The chassis design............

In this section, it will be discuss on how to build the chassis of two wheeled balancing robot and material selected. Therefore, a proper planning is needed to ensure this project accomplish. Furthermore, the design of the robot chassis is kept as simple as possible but not compromising the objective of the project.

i have no time to think other design because of limitation of time, by doing a research and comparing with other model from internet. this what i got heee. just a simple model, i make it from perspex.



The robot chassis design is constructed using 4 Perspex plate as bases, 2 plate with the same dimension (220x220mm) and other 2 plate with different dimension (220x170mm), 4 aluminum rod with 400mm long and 5mm in diameter, the robot is tighten by screw and nuts. The robot design is mounting in a layer for component and sensor placing. The chassis height can be lowered and increase when desired. This adjustment is useful for calculating the center gravity (CG) of the robot.



"this material i choose because to reduce the cost. the price is only RM25 ringgit including tires, perspex, aluminium rod bolt and nuts.





The controller.......



The controller is used to implement the control algorithms is PIC16F877A microcontroller from Microchip. The reason why PIC16F877A is chosen due to easy of programming, it only 35 single-word instructions to learn, it operating speed is 4MHz clock input with 200ns instruction cycle, operating with DC voltage. It memory include 8Kx14 words of flash program memory,368x8 bytes of data memory(RAM), 256x8 bytes of EEPROM data memory. It pinout is 40 pin and this is suitable for high input output control. The program language use in this controller is PIC Basic Pro.
The controller has the analog-to-digital (A/D) converter built-in, the feature in controller is very important for input and output hardware communication, for example sensor and the actuator.



i got this microcontroller from penang electronic shop cost around RM30 ringgit.



the actuator.......



The actuator is 12 volt DC motors. DC motors take direct current (PWM) voltages as input and convert it into rotation movement. DC motors are reversible by reversing the polarity of the voltage supplied to the motor. Varying the voltage input into the motor will vary the speed of the motor. The motors used must be fast responding and high torque. SPG50 60K DC geared motor from Cytron was chosen as balancing robot’s actuator. SPG50 60K motor is a DC Gear Head Motor with 60:1 reducing gearbox. The continuous torque of the motor is 588 mNm. The speed of the motor is 56 rpm.



you must select the proper geared DC motor because it will result the robot performance, what can i say is plez use the DC geared motor with high tork and low speed, i got this motor from my awek's friend(awek usop) heee....... she buy for me. thank!



but the price is very expensive!!, better find your own DC motor.
lot of money for this!!!

the sensor.......

Two GP2D12 distance measurement sensor and gyro sensor is using; Two general purpose distance measuring sensors (GP2D120) were used on the balancing robot in order to detect the current angular position of the robot. The sensors are mounted on Perspex plate and placed at the front and back of the robot. The line of sight is toward the ground at an angle of 90 degree. The output of the sensors is an analog voltage. The GP2D12 can sense a height from minimum 4cm to maximum 30 cm. The robots always balance by measuring the height at the front and back of it-self and rock the wheels to maintain equal height.

as you can see, in the chassis pic above the distance sensor is in the red colour.

i'm really tired rite now, i will continue writing for next post.