Haptic Shared Control by Adjusting the Stiffness of a Joystick Based on Sensor Systems Reliability for Underwater Vehicles

Haptic shared control is a framework in which automation and the human pilot utilize the same operational input terminals to control a system. Both of their responses to automation failures are important. This paper describes the concept of adjusting the stiffness of the control stick based on the reliability of sensor systems. This helps human pilots perceive when to intervene and when to follow (just put their hand lightly on the stick) by changing the stiffness of the control stick. First, the haptic feedback design for changing the stiffness of a joystick is explained. Then, in the experiment, participants perform the task of keeping a remotely operated underwater vehicle stationary in front of a target in water stream using a joystick with three different haptic feedbacks: ours, constant high stiffness, and constant low stiffness. The experimental results indicate that our strategy increases control accuracy without increasing the human pilot's workload while allowing the human pilot to understand whether the human pilot or the automation should be currently in control of the task or action being performed. As the unexpected underwater environment adversely affects the sensor systems, our findings can be expected to play an important role in improving the control performance in the sea. Furthermore, it may inform the design of haptic feedback systems for low sensor visibility scenes.