Project #4 - Odometry

Your team will implement wheel encoders for estimating the position of your robot relative to a home position. Your team must decide whether to build a simple encoder consisting of one photoreflector per wheel (and take care of the sign of pulses in software) or to build a more sophisticated quadrature encoder that counts up and down based on the output phase of two photoreflectors per wheel. You have the option of using code available online if that helps. As discussed in class, the pulse counter will be realized in the form of an interupt. Your team must decide whether to build a simple encoder consisting of one photoreflector per wheel (and take care of the sign of pulses in software) or to build a more sophisticated quadrature encoder that counts up and down based on the output phase of two photoreflectors per wheel.

Quick Start:

• The Vcc pin of the photoreflector is connected to the 5V pin on the Arduino, the GND pin is connected to the GND pin, and the OUT (signal) pin is connected to a digital I/O pin on the Arduino, The Uno has two interupts: Pin2(number 0) and Pin3(number 1).
• The sensor: model , schematic , and specs

Other Resources

• Library
• Sensor board description
• Application Notes
• Reading rotary encoders
• Arduino Forum about quadrature encoder thread

Materials:

• 2 Pololu QTR-1RC sensors

Report:

• implement your quadrature encoder to servo to constant radius paths. Measure the encoder pulses on each wheel and turn these into observed velocities. Adjust them as necessary to track the paths you wish to follow.
• estimate x, y, and theta of the robot by integrating the encoder displacements.