Decreasing the Apparent Inertia of an Impedance Haptic Device by Using Force Feedforward

When using a haptic device in unconstrained movement, the user should experience only minor inertia. For certain tasks, the workspace of the device should be similar or even larger than that of the human arm. This condition tends to lead to large devices that often present high rather than low inertia. This brief describes a method to decrease the inertia felt by users of impedance haptic devices. It has been successfully implemented in the LHIfAM haptic device. The effect that this strategy has on stability and virtual contact is also illustrated.