Impulse force presentation during ball kicking by lower limb exoskeleton with MR fluid brake

In recent years, the widespread use of a head-mounted display has facilitated access to virtual reality spaces. Force feedback devices have been developed to allow users to manipulate virtual objects. Typical installation-type devices are large and limit the user's range of motion. Therefore, we focused on a wearable exoskeleton-type device and used a passive magnetorheological fluid brake to provide force feedback to the lower limbs. In this study, we focused on the fact that the force applied to the lower limbs, such as kicking a soccer ball, can be expressed as an impulse. We investigated how to express the force sensation by changing the torque applied to each joint and the applied time. Experiments were conducted under different impulse conditions, and it was found that the smaller the torque generated and the longer the applied time, the lower the sense of reality. Based on these results, experiments were conducted under constant impulse conditions, varying the torque generated and its applied time. It was found that the size of the impulse is not proportional to the sense of reality and that there are optimal conditions for obtaining a high sense of reality.