Builders guide robot pacman.pdf

3.0 MotorsIn order to have Pac-Man and the Ghost traverse through the maze efficiently, themovements of the robot need to be precise and easy to control. Our design requires therobots to make near perfect 90 degree and 180 degree turns on a touch button command.Therefore, it is critical to have the right motors for the purpose and a control mechanism,which makes it easy for the microprocessor.3.1 Motor SelectionFor the robots’ drive motor, we had to choose from three types of motors: DC,servo, and stepper motors. DC motors are capable of providing high speed andtorque for the robot, but they require the proper gearboxes and shaft encoders toachieve the desirable control. As for the servomotors, they have a much simplercontrol mechanism, but their speed is limited, and in most cases, they are notcapable of the full rotation needed for driving purposes.As a result, we decided to settle with stepper motors. Stepper motors are easy tocontrol with the help of proper translation logic and it can be used to drive therobot without any modifications. However, there is one disadvantage that we didnot find out until we started working with them. Although the stepper motors arecapable of full rotation, in most cases, they are not designed to provide enoughtorque for driving small robots. Fortunately, there are special high torque steppermotors that are designed for driving applications. For our robots, we decided touse 12VDC unipolar stepper motors, the 55M048B2U from Thomson IndustriesInc.; Figure 10 below shows the dimension of the motor.6