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Poco - Quadruped Walking Robot


Poco is a simple quadruped walking robot with 2 active-DOF in each rear leg, and 3 active-DOF in each front leg.

In Poco, the front legs have vertical-axis rotation, similar to that in human legs. This is an experimental arrangement, meant to aid in turning movements. This is being used instead of a front-rear horizontal axis (as in Aramies [1] [2]), since we expect to be able to get a similar effect on turning as the front-rear axis without having to use large torque servos at the uppermost shoulder joints. In humanoid biped robots, the hip joint [sideways axis] servos experience the largest torques.


  • frame dimensions: approx 10" (254mm) long, 9" (228mm) wide in front, 6" (152mm) wide in back.
  • leg extension below frame: approx 7" (178mm) in front, 6" (152mm) in rear.
  • frame material: copper-coated pcb.
  • leg brackets: Lynxmotion SES.
  • weight: total = 42-oz (1190gm), frame+controller = 11-oz (311gm), 10/ea servos+SES = 26-oz (736gm), 5/ea AA-Cells = 5-oz (142gm).
  • The photo on right illustrates the left-front leg (to left in photo) folded up, and the left-rear leg (to right in photo) in standup straight position.

    In the front leg, the 2 lower joints represent shoulder (upper) and elbow (lower) joints, analogous to biological quadrupeds. In the rear leg, the joints represent hip (upper) and knee (lower).

    The vertical-axis rotary joint is "experimental", and was added to aid turning movements.

    The photo on the right illustrates the positions of the left-side legs when the rear leg is taking a step forward.

    (The rear leg has a rubber foot that had not been added to the front leg as yet).

    The photo on the right shows Poco with both legs fully retracted, as it would be in a "resting" position.

    Note that the "kink" was specifically added to the legs to facilitate this folding, but the kinks have no affect on operation of the legs when fully-extended (as shown in the first picture above), other than to change the servo angles by a few degrees.

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    © Oricom Technologies, updated Jan 2008