After having constructed the prototype leg module for Pentagoon, we felt able to proceed to the stage of manufacturing the 5 final-version legs along the same lines.

Pictures:
(see the prototype page for computer-generated pictures of the leg)

Mechanical details:
The mechanism for the final-version legs is the same as for the prototype leg - in fact, for the first final-version leg we literally transplanted everything except the soldered-in piece of tube to the new board.

Electronic details:
The local controller (or "ganglion") for the leg is built onto the piece of circuit board supporting it. It is based around an Atmel AVR 1200 RISC microcontroller, which is in serial communication with the AVR mega323 central controller. Both in terms of hardware and software it is based on a 2 servo pan-tilt head for a small video camera originally constructed by Phil Preston; the servo control and software RS232 UART portions of the firmware and the corresponding parts of the board have been left unchanged while the foreground processing and the other I/O areas of the board have been modified to suit the robot.

The microcontroller has 15 general-purpose I/O pins, of which 2 are used for the serial communications link; 3 are used for the programming connector, to enable the microcontroller to be reprogrammed in-situ; 2 are outputs, controlling the two servos; 5 are digital inputs, receiving data from the two bumper microswitches on the foot, the ground-contact microswitch, the photoreflective IR odometer and the tilt switch; and the remaining 3 are spare, brought out to a header connector on the board. The spare pins also have the option of being jumpered into other components on the board for debugging purposes: 2 LEDs are present, which are currently used as a "heartbeat" (flashing while the board is active) and a command toggle, and the third is connected to a push switch.