Robot-Assisted Therapy of the Arm

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The development of robotic treatments is motivated by the need to improve clinical outcomes, the increase of public health burden associated with stroke-related disability, and the current emphasis on cost-reduction in healthcare. Most stroke survivors receive one-on-one physical and occupational therapy for the resulting sensorimotor impairments. Neurorehabilitation of the upper limb is often abandoned early in favor of compensatory strategies. This decision is motivated by decreasing reimbursable patient-therapist contact time and the fact that the remaining intact limb with proper training and adaptive aids can perform most activities of daily living (ADL) involving the upper limbs. However, performing ADL one-handed is often cumbersome, increasing the time required and difficulty of the task, compared with performing ADL two-handed. These factors suggest that robotic devices can provide effective training for neurorehabilitation without increasing the burden on the clinicians or increasing the costs of healthcare. If commercially viable versions of these robotic devices can be developed, integration of robotic therapy into current practice could alleviate the labor-intensive aspects of neurorehabilitation and thereby increase the efficiency and effectiveness of therapists. [1]

InMotion2 Robot [2]

Robotic rehabilitation is all about improving patient recovery and reducing impairment, unlike assistive technologies that compensate, or "work around," a patient's disability. During therapy, a suite of video games fully engages the patient, while the robot provides graded assistance. If a patient is unable to move, the robot moves the patient's hand to the target. If a patient moves inappropriately, the robot continually guides the patient's hand toward a trajectory toward the target. And as a patient gains the ability to control the limb, the robot provides less assistance. When InMotion2 (above) is coupled with the Wrist Robot, five active degrees of freedom enable even more complex movement

Another motivation for developing robotic treatments relates to the growing evidence that recovery from brain injury is heavily influenced by the sensorimotor experience following the injury. An earlier seminal study showed that the highly repetitive task training of constraint-induced (CI) movement therapy, also known as CI therapy, can lead to gains in motor function. More recent studies continue to confirm the positive effects of repetitive movement training on motor recovery after stroke. While these studies focused on nonrobotic movement training, some evidence exists that robotic repetitive movement training might be even more effective, especially in moderately to severely impaired subjects who have difficulty performing unassisted repetitive movements. The rationale is that robots might enrich the sensorimotor experience by providing novel patient-environment interactions during active repetitive training. These novel training modes might eventually prove to be more effective than nonrobotic repetitive training.

                               Figure 2. A rendering of the overhead view of robot-assisted therapy workstation configured for a subject with left hemiparesis.

Robot-assisted arm therapy prototype.

Each forearm rests in a splint attached to bilateral

mobile arm supports that bear the weight of the limbs.

Angle encoders at each joint measure forearm position and orientation.


Overhead view of robot-assisted therapy workstation configured for a subject with left hemiparesis. Subjects with right hemiparesis sit facing the opposite direction. The initial MIME prototype used a Puma-260 robot (A) coupled through a force and torque transducer (B) to one of the forearm splints (C). The splints, which were free to rotate and tilt at the end of modified mobile arm supports (D), supported the weight of the forearms. In the current MIME workstation, the robot is a Puma-560, the paretic limb mobile arm support is eliminated, and a 6-DOF-position digitizer replaces the contralateral support. [3]