Numerous haptic devices have been developed for
upper-limb neurorehabilitation, but their widespread use has
been largely impeded because of complexity and cost. Here,
we describe a variable structure pantograph mechanism combined
with a spring suspension system that produces a versatile
rehabilitation robot, called Universal Haptic Pantograph, for
movement training of the shoulder, elbow, and wrist. The variable
structure is a 5-degree-of-freedom (DOF) mechanism
composed of 7 joints, 11 joint axes, and 3 configurable joint
locks that reduce the number of system DOFs to between 0 and
3. The resulting device has eight operational modes: Arm,
Wrist, ISO (isometric) 1, ISO 2, Reach, Lift 1, Lift 2, and Steer.
The combination of available work spaces (reachable areas)
shows a high suitability for movement training of most upperlimb
activities of daily living. The mechanism, driven by series
elastic actuators, performs similarly in all operational modes,
with a single control scheme and set of gains. Thus, a single
device with minimal setup changes can be used to treat a variety
of upper-limb impairments that commonly afflict veterans
with stroke, traumatic brain injury, or other direct trauma to the
arm. With appropriately selected design parameters, the developed
multimode haptic device significantly reduces the costs
of robotic hardware for full-arm rehabilitation while performing
similarly to that of single-mode haptic devices. We conducted
case studies with three patients with stroke who
underwent clinical training using the developed mechanism in
Arm, Wrist, and/or Reach operational modes. We assessed outcomes
using Fugl-Meyer Motor Assessment and Wolf Motor
Function Test scores showing that upper-limb ability improved
significantly following training sessions.
Key words: arm therapy, haptic device, haptic training, pant