During quadrupedal robot locomotion, there is pitch, yaw, and roll of the head and body due to the stepping. The head motion adversely affects visual sensors embedded in the robot's head. Mammals stabilize the head using a vestibulocollic reflex that detects linear and rotational acceleration. In this paper we describe the use of a machine learning algorithm that utilizes signals from an artificial vestibular system that has been embedded in the robot's head. Our approach can rapidly learn to compensate for the head movements that appear when no stabilization mechanism is present. The stabilization using a Sony Aibo robot occurs in only a few gait cycles.

The angular vestibulo-ocular and opto-kinetic reflexes (aVOR and OKR) combine to provide compensation for head rotations in space to help maintain a steady image on the retina. We previously implemented an artificial angular vestibulo-ocular reflex with a fully articulated binocular control system in a quadruped robot head. In this paper, we describe the implementation of artificial opto-kinetic and linear vestibular ocular reflexes (OKR and lVOR) that use inputs from an artificial vestibular sensor and a binocular camera system to compensate for linear movements of the head and visual motion to stabilize images on the cameras. The object tracking algorithm was able to fixate a steady object in the camera's field of view during linear perturbations of the robot's head in space at low frequencies of movement (0.2-0.6 Hz), simulating the linear VOR. We implemented an algorithm that combines the linear VOR and OKR model and computes changes in relative pose of the cameras with respect to the object being tracked. The system provides compensatory angular movements of the Ocular Servo Module (OSM) to stabilize images as the robot is moved laterally.

Studies of primate locomotion have shown that the head and eyes are stabilized in space through the vestibulo-collic and vestibulo ocular reflexes (VCR, VOR). The VOR is a reflex eye movement control system that stabilizes the image on the retina of the eye during head movements in space. This stabilization helps maintain objects of interest approximately fixed on the retina during locomotion. In this paper we present the design and implementation of an artificial vestibular system, which drives a fully articulated binocular vision system for quadrupedal robots to maintain accurate gaze. The complete robot head has 9 degrees of freedom (DOF): pitch, yaw, and roll for the head and 3 DOF for left and right cameras. The SONY AIBOreg quadruped robot has been modified with additional hardware to emulate the vestibular system and the vestibulo-ocular reflex in primates.