MICROMOUSE: An Autonomous Robot

Electronic circuitry : Details regarding sensors, microcontroller, motor driver. Microcontroller P89C51RD2BN is the heart of the circuit. The sensing is done via GP2D12 (Distance Sensing module by SHARP). The analog output voltage of the sensor is given to ADC 0804. The ADC is interfaced to Microcontroller unit. 5 volt D.C motors (Coil resistance: 12 ohm) are the thrusters to the mouse driven by L293D (Driver). The microcontroller provides appropriate control signals to the motors through driver after sensing the input from the sensors. Simple limit switch is used for the front wall detection. The supply to the circuit is provided through 9 volt rechargeable battery using 7805 regulator.

The microcontroller is programmed using serial port of the computer. The clocking circuitry for the Microcontroller and the ADC is provided separately on the same PCB.

Image 1

Mouse Structure : Details regarding chassis, positioning of sensors, wheels . The mouse structure is made totally out of scrap. The complete mouse structure has the maximum dimension as: Length = 11 cm, Breadth = 7 cm and Height = 5 cm.

The main PCB itself acts as the mouse structure. Two motors are tied beneath this PCB at the back (clearly visible in the bottom view above). Gears of diameter 2.6 cm are fixed to the motor shaft, which acts as the wheels of the mouse. A ball roller mechanism (made out of scrap) is attached below the PCB in front to provide free wheeling action. Both the sensors (side and front) are attached to the PCB and remain stationary throughout.

The structure of the mouse is clear from the IMAGE 2 below.

Image 2

The two specialty of the mouse are as follows:

1. The mouse structure is made out of scrap. The motors are pulled out from an old CD ROM. The wheels (Gears) are also from the scrap CD ROM mechanism. The ball roller mechanism (provided for free wheeling action in the front) is also made using part of an old floppy drive. The front wall sensor is a simple limit switch taken from an old mechanism.

2. The second specialty of this mouse is the size: The mouse can easily fit into a box with dimensions:

11 x 7.5 x 5 (All dimensions in cm). The size of the mouse can also be depicted from the IMAGE 1. As seen from this image the mouse can easily fit in the palm of my hand. For efficient utilization of the circuit space on the PCB the space below the IC’s is also utilized for placing the circuit components.

Thus the cost of the mouse is only the cost incurred in the circuit components.

Image 3