Design and implementation of a closed-loop static balance system for the YICAL Leg 2 biped

In this paper, we report a closed-loop system for introducing static balance to a newly constructed biped called YICAL Leg 2. In the system, an attitude estimation system was developed to detect changes in the tilt and rotation along the hip axis of the biped. The attitude estimation system utilized an accelerometer and a rate gyroscope. A sensor fusion algorithm programmed in a digital signal processor combined the signals from the two sensors for a more accurate estimate of the biped´s orientation. Based on the information obtained from the attitude estimation system, the Balancing and Position Control Algorithms were programmed to execute reflex motions to counter instabilities applied to the bipedal robot. Experiments with the system have shown that researchers were successful in enabling the biped to regain and retain balance by sensing external disturbances and executing proper reflex.