Neurophysiological models of gaze control in Humanoid Robotics

Abstract

This work present a robotic implementation of a neurophysiological model of rapid orienting gaze shifts in humans, with the final goal of model parameters validation and tuning. The quantitative assessment of robot performance confirmed a good ability to foveate the target with low residual errors around the desired target position. Furthermore, the ability to maintain the desired position was good and the gaze fixation after the saccadic movement was executed with only few oscillations of the head and eye. This is because the model required a very high dynamic. 9.1. Robotic point of view The head and eye residual oscillations increase linearly with increasing amplitude. In Fig. 16 is evident that the residual gaze oscillation is less than head. This is explained with the compensation introduced by the eye oscillations which compensate the gaze which becomes more stable. We explain these findings by observing that the accelerations required to execute (or stopand-invert) the movement are very high especially for the eye movement. Even if the robotic head was designed to match the human performances (in terms of angle and velocities) in its present configuration it is still not capable produce such accelerations. This is particularly evident for the movement of the eye because the motor has to invert its rotation when the fixation point is first achieved. With respect to the timing of the movement it has been found that the results of the experiments are in close accordance to the data available on humans (Goossens and Van Opstal, 1997). The same conclusion may be drawn for the shapes of the coordinated movement that can be directly compared to the typical examples reported in Fig. 14. Figure 16, 17 show that the model is capable of providing inadequate control of the redundant platform. The system response is very fast, due to the robotic head platform design. TGst time take into account the problem of eye-head coordination and the very high acceleration. The head is voluntarily delayed less than 30 millisecond after eye movement, according to human physiology, by means of Ph block (Goossens and Van Opstal ,1997). 9.2. Neurophysiological point of view A typical robotic eye-head movement is shows in Fig. 14