MARS Development Project D1:
Cooperative Control Strategies for Robot-Aided Gait Therapy
Executive Summary of Aims:
In recent years, there has been a considerable growth in the number of robotic devices available for retraining patients after neurological injuries such as stroke. These innovations have arisen because findings from animal models suggested that replicating normal gait patterns on a treadmill, while supporting patient weight, could improve recovery of gait, and also bone and muscle health. Such gait retraining was done originally by manual limb motion on the treadmill by the therapists, however, this approach is very labor intensive, and can give rise to therapist injuries. Accordingly alternative approaches, such as the Lokomat®, have been developed. The Lokomat is a powered gait orthosis that moves the limbs of patient as he/she is suspended above a treadmill. The Lokomat is routinely configured as a position controller, and it is used to replicate a standard normal gait pattern. Our objective in this proposed development study is to design and test novel Lokomat controllers, called “Cooperative Controllers”. In a broad sense, these controllers replicate the behavior of the therapist, in that they allow free motion when the movement path of the limb is accurate, yet intervene when the motion is in error. These controllers couple the intended motion of the subject with the actual motion of the limb and robot, including the motion of the treadmill.
For the first 2 years, these controllers will be designed and tested in bench mode in Zurich (ETH Zurich and University Hospital Balgrist, Zurich) and then in normal control subjects. In the third year, we will begin more intensive and rigorous testing of the controllers, using Lokomats based in Zurich , and at the RIC. Over the last 2 years of the study, we will compare the performance of the Lokomat using these new cooperative controllers with the classic position controlled Lokomat, in a small population of patients.