Modeling Verticality Estimation During Locomotion

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 comprises 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 headplatform 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 disturbances generated by locomotion and simplifies state observation in a non-inertial frame, without the need for fixed external beacons.