Research

Handheld haptic devices are often limited in rendering capability, as compared to traditional grounded devices. Strenuous design criteria on weight, size, power consumption, and the ungrounded nature of handheld devices, can drive designers to prioritize actuator force or torque production over other components of dynamic range like bandwidth and transparency. Hybrid actuation, the use of passive and active actuators together, has the potential to increase the dynamic range of handheld haptic devices due to the large passive torque capability of passive actuators, the high bandwidth of conventional DC servomotors, and the synergy between them. However, to date the use of hybrid actuation has been limited due to the highly nonlinear torque characteristics of available passive actuators that result in poor rendering accuracy. This paper describes a novel hybrid actuation approach and control topology, which aims to solve actuation challenges in hybrid and handheld haptic devices. The performance of the device is assessed experimentally, and the approach is compared to existing handheld devices.