27 Mar 2004 Spoons   » (Observer)

The robot now has two OOPIC-based CPU boards, one designed to specialise in driving the motors, and one as a master controller CPU.

The motor OOPIC board sends PWM out to the 4QD motor controller boards, and monitors the current drawn by the motors, and signals from a quadrature encoder mounted on each drive shaft.

The master controller OOPIC has RS232 interfacing electronics, and will eventually interface to a central PC/104 system running Linux, via the SCP protocol. Its job is to receive messages from the PC/104 system and route them to the appropriate board via I2C, for example to control the motors or to request sensor information.

I've also built a maths co-processor board, based on the Al Williams PAK-II, which will be used by the OOPIC boards for fast flaoting-point calculations. These are required for a PID speed control algorithm on the motor board (although not strictly necessary, floating point will make this considerably easier), and by a board yet to be built which will control a set of sonar sensors mounted on pan/tilt units. The board will use the maths co-processor to perform geometrical calculations to merge data from sonars placed at different positions around the robot.

The next job is to write and test the PID speed control software.

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