  Grounded haptic devices can provide a variety of forces but have limited
working volumes. Wearable haptic devices operate over a large volume but are
relatively restricted in the types of stimuli they can generate. We propose the
concept of docking haptics, in which different types of haptic devices are
dynamically docked at run time. This creates a hybrid system, where the
potential feedback depends on the user's location. We show a prototype docking
haptic workspace, combining a grounded six degree-of-freedom force feedback arm
with a hand exoskeleton. We are able to create the sensation of weight on the
hand when it is within reach of the grounded device, but away from the grounded
device, hand-referenced force feedback is still available. A user study
demonstrates that users can successfully discriminate weight when using docking
haptics, but not with the exoskeleton alone. Such hybrid systems would be able
to change configuration further, for example docking two grounded devices to a
hand in order to deliver twice the force, or extend the working volume. We
suggest that the docking haptics concept can thus extend the practical utility
of haptics in user interfaces.
