Control of a hexapodal robot
نویسنده
چکیده
The Dynamical Systems Design department at the Eindhoven University of Eindhoven is actively researching the design and control of robotic systems. Examples are Amigo, the service robot competing in the RoboCup @home league, the mid-size league soccer robots of Tech United and the Tulip which is the humanoid robot competing in the RoboCup humanoid adult league. One of the new research activities is the hexapodal robot, a legged robot which eventually should participate in the RoboCup Middle Size League. Therefore the final goal in the development of the robot should be to make it run. A first prototype is developed that is used as a testbed. The hexapod has 3 degrees-of-freedom per leg where each rotational joint is separately actuated so that the robot has 18 actuators. The torque of the actuator is transmitted to the joint using a torsional spring transmission. The introduced compliance improves the impact safety of the hardware and can decrease energy consumption when correctly exploited. The hexapod is equipped with an inertial measurement unit and each joint and actuator has a position encoder. A software structure is developed to control the motion of the hexapod. The control is developed in open-source software, mainly in Orocos. To control the hexapod the controller is divided in two main functions. The first controls the leg in joint space when it is positioned in the air by using SISO control techniques. The second controls the body by using linear virtual actuators in combination with the joint space controllers. The resulting forces of the virtual actuators determine the torques on the joints using a force distribution algorithm. The results of the overall performance as well as of individual components are presented. Although some improvements can still be made, the robot is able to walk. Using more advanced control techniques like learning could improve the walking speed. Exploiting the compliant dynamics and a redesign of the hardware eventually should result in a running hexapod.
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