Although the electronics and sensors are a vital part of any autonomous machine, they were not the emphasis of this project. Other researchers have shown advantages of sensor-rich robots [Ferrell 93, Angle 91]; Boadicea has the simplest sensors and software that allow it to demonstrate its mechanical capabilities.
Boadicea's microprocessor is a Motorola 68332. This processor combines the functionality of a 68020 with a specialized Timer Processing Unit (TPU) [Motorola 90]. Boadicea uses the TPU to produce the Pulse Width Modulation (PWM) wave forms that control the valves. I built a mother board for Boadicea that contains the interface to the sensors and valves.
Boadicea is programmed in L, a multi-tasking version of Common Lisp written by Rodney Brooks [Brooks 94]. This language has several features which make it appropriate for controlling Boadicea: it provides an interpreter which facilitates debugging and testing code, and it is the standard programming language in our laboratory, making it easy to transfer innovations from one robot to another.
All of the software required to run Boadicea's software, including the interpreter, reside in EPROM on the 68332 circuit board.
The complexity of a robotís behavior is determined in part by its sensors; it is difficult to make good decisions if there is limited information available. Although insects have several hundred mechanosensory signals from each leg [Delcomyn, et al 94], technological limitations prohibit this level of complexity on robots. Insects sense leg position, velocity, acceleration, loading, and contact with the environment [Delcomyn, et al 94]. Robots can measure these same quantities.
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