Operability of Joystick-Type Steering Device Considering Human Arm Impedance Characteristics

In this paper, we present some results from the study on the impedance characteristics of a human arm during the execution of vehicle steering control tasks by using a joystick-type steering device. We propose a new model of human-machine interaction where the damping coefficient of the interface device can be tuned to match the impedance characteristics of the human arm. To verify the proposed model, we developed a special experimental setup. We used a robot and force/torque sensors to simulate the joystick operation. We explored human-machine interactions when the operator uses only one hand to control the vehicle. The reaction forces of the joystick were simulated by a virtual impedance field tuned to match human arm impedance. In the tests, we simulate situations when the movement of the joystick in the forward-backward direction sets the speed of the vehicle while the lateral rotation of the same control stick changes the turning radius of the vehicle. The robot allowed us to simulate various impedance characteristics. With the tests, we investigated the operability of the simulated vehicle by tuning the viscosity coefficient of the joystick in order to match it with the stationary human arm impedance and time-varying human arm impedance. The test results allowed us to propose a new method to improve the operability of a joystick-type steering device, based on the online adaptive matching of the impedance characteristics of the human arm. The usefulness of the proposed method is confirmed through experiments.