Extending rehabilitation robotics from automated to instrumented training: Assessment Tools for the Lokomat

Neurological disorders, such as spinal cord injury, stroke, and traumatic brain injury, affect the motor perform- ance of affected individuals. The most important result is the loss of function, e.g. gait function. Muscle weakness and increased involuntary muscle tone (spasticity) are most commonly affected. Robotic rehabilitation devices are available for re-training impaired functions. These devices are equipped with actuators and position and force sensors. Beyond pure training, advanced tools can use these sensors and actuators to measure physiological and other properties of the patient using the device. We report here the design and implementation of assessment tools the rehabilitation robot Lokomat® (Hocoma AG, Switzerland) that supports patients during body-weight sup- ported treadmill training. One of these tools measures the mechanical stiffness during controlled passive move- ments of the legs. Mechanical stiffness is higher in patients with higher spasticity. Another tool measures volun- tary muscle force against a fixed resistance of the robot. We suggest that the use of robotic devices for assessment of patients during their training will be an important addition to robotic-supported therapy.