Specifications

23
Figure 4.3: Motor setup Figure 4.4: Chassis design
The chassis is a 100 x 100mm box section of aluminium commonly found on patio
posts. The axle holes were formed with a die grinder and are designed for the motors to
bolt straight into. The trundle wheel was placed on temporarily until final dimensions
are known for extra hardware (batteries, microcontrollers, wiring etc).
4.3 Odometer Sensors and Interrupt Control
4.3.1 Building the odometer sensors
As explained earlier, it is necessary for the Mobile Robot to be able to drive in straight
lines between obstacles. For this to occur it is necessary to calculate the turns of each
wheel (or motor) to compare against the other. There are various methods available for
this; however the easiest and most successful technique is to insert a sensor on each
motor to count the revolutions. In this case an infrared LED and receiver have been
used to count the revolutions. Figure 4.5 shows how this sensor is implemented.
Figure 4.5: Odometer Sensor