Modeling Verticality Estimation During Locomotion

Abstract Estimation of the gravitational vertical is a fundamental problem faced by locomoting biological systems and robots alike. A robotic model of a vestibular system is suggested with the purpose of explaining an observed phenomenon—head stabilization during locomotion. The mechanical model of the vestibular system com-prises a damped inclinometer and an inertial measurement unit which are mounted on an actuated orienting platform (a robotic head). Generic linear control is employed to stabilize the head-platform while the vestibular system exercises an extended Kalman filter algorithm to estimate the gravitational direction in space. It is demonstrated that stabilization of the head-platform is essential in achieving accurate verticality estimation as it attenuates the dis-turbances generated by locomotion and simplifies state observation in a non-inertial frame, without the need for fixed external beacons.