Niphon Lapanaphan and Erik L.J. Bohez
Actuator fusion, haptic system, virtual reality, impedance control, brakes
In a conventional haptic system, haptic interactions have mostly relied on active actuators, which involve complex control methodologies, yet impedance rendering is unsatisfactorily bounded by a stability limit. Moreover, overshoots leading to instability are still a concern. This paper presents a new concept of high impedance actuator fusion (HIAF) to increase the impedance range with reduced overshoots in a haptic system by using a motor, a damping brake, and a magnetic brake. The approach utilizes the unique characteristics of the devices to manipulate the system variables in a more stable way. The system was modelled as a linear time-invariant system with an impedance control method. A new stability condition was defined, and some selected simulations and experiments were presented for the worst-case scenario of a 1-DOF haptic device using only virtual stiffness. The results showed that HIAF haptic system can substantially extend the stability boundary of the virtual stiffness. It can also reduce the overshoots and stably increase the impedance.
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