Dordevic GS, Rasic M, Shadmehr R (2005) Parametric
models for motion planning and control in biomimetic
robotics. IEEE Transactions in Robotics 21:80-92.
Abstract We describe the design, testing and
tools to build parametric models of a six-legged cockroach-like robot for
velocity control without precise knowledge of robot's geometry or its inertia.
Robot legs were made by Shape Deposition Manufacturing and were compliant at
the "knee". These kinds of robots usually have a limited number of
actuators and a small number of low-cost sensors. Consequently, they are
difficult to control with analytic models. Our goal was to design a very fast
robot that could run in a straight line over short distances at a desired
velocity. We incorporated such legs into a novel body design where position and
orientation of the legs were chosen to enhance static stability. Robot design
proved to be robust as the machine did not suffer any failure in over 20,000
runs. We found that body pitch angle was a crucial parameter in control of
speed of running. To control this angle, we built a parametric model that
related leg orientation to pitch angle. We experimented with various leg
stiffness parameters and built a comprehensive parametric model that quantified
performance as a function of this parameter, as well as body pitch angle,
ground slope, and body mass. When these parameters were optimized, the robot
consistently achieved a speed of six body lengths per second, even when pulling
a large load in the form of a trailer cart.
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