Design and evaluation of unit for haptic device on foot

Walking is a popular recreation activity. In addition, it is a mild and healthy exercise for the elderly. However, people suffering from physical and / or cognitive disorders have a difficulty in going out and walking in real environments. Therefore we have proposed a virtual walking system with a haptic device on feet. This system consists of visual, sound, and haptic devices to present various kinds of ambient information for users. The development of the haptic interface for feet soles is a main topic of this paper. We discuss a use of magnetic field sensitive elastomers (MSEs) as working materials for the device. In the previous report, we developed an electromagnet as a testbed of MSE and evaluated it performance. According to the measurement of planter pressures, this device can perform different pressures on soles by applying magnetic field. The result also implied necessities of the improvement of the magnetic circuit and basic structure for more feasible device. In this paper, we propose a new structure to control a frictional resistance force that is generated on the surface of the MSE and a metal pin. In addition, we propose to use this device as a single unit for the haptic device on feet. According to the compressive test of the unit, the maximum force that can be controlled with the unit is insufficient yet. However, it appears that we can control frictional force with the proposed structure. We also conducted a simulation to estimate required values of the performance for the unit. It is much higher than the current state of the unit. We have to improve the performance of the unit in the future.