Keywords: Control , Hardware , Haptic display, passive actuator

ABSTRACT - This paper describes the design and implementation of a hybrid active/passive force feedback device. It has a single degree of freedom that is actuated by a motor and a brake pair. The use of a motor and a brake allows various objects to be simulated without a stability problem and related safety issues involved with using high torque motors only. The device performance is measured by its ability to simulate various test objects. Simple test objects are modeled as a benchmark test of the system?s performance. The force feedback device is capable of simulating forces in a variety of virtual environments. This device demonstrates the effectiveness of a hybrid active/passive haptic actuator. An analysis of the use of hybrid active/passive actuators in the 2 degrees of freedom case finds that they are capable of simulating a rigid body in a broad range.

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[...] there is a trade-off between stability and performance.
[...] He showed that increasing passive damping degraded the performance. The use of passive components is a method for providing stability with a haptic interface.

This paper shows that the hybrid active/passive approach improves both stability and performance.


Passive actuators such as brakes can reflect much larger forces than active actuators without threatening the user?s safety. Because passive actuators can only remove energy from a system, they are intrinsically stable. [...] Moreover, passive actuators can provide higher torque than active actuators of the same physical size. Passive actuators, however, cannot simulate a model of an energy storage element such as a spring, because of their energy dissipating characteristics.

It is desirable that joystick inertia, damping, and friction are minimized to implement free space environments.

System: The active actuator is an AC servomotor of its nominal torque, 0.319Nm, and a magnetorheological brake is used as the passive actuator. This brake provides variable resistive torques according to the amount of external current.