Design and control of Active Knee Rehabilitation Orthotic Device (AKROD)

Patient populations with stroke or neurological disorders who have lost their walking capabilities regain ambulatory motor control functioning by undergoing physical rehabilitation. Conventional techniques are labor intensive and often require one-to-one administration, thereby making it time consuming for the therapist. This in turn leads to increased costs and reduced training duration. Research has shown that patient can improve their muscle strength and movement pattern by practicing locomotor related activities. With the advancement of robotic technologies in the recent years has led to the development of automated gait training devices to enable and assist patient to recover their motor skills. One such set of treadmill-based devices provides the means for intense rehabilitation but is very expensive and require large operational space.;Presented in this thesis a low cost portable device called Active Knee Rehabilitation Orthotic Device (AKROD). AKROD is designed and developed for gait rehabilitation of patient post-stroke and is targeted towards individuals who have regained a certain level of motor control but not yet fully attained normal walking capabilities. AKROD functions by providing active assistance to the patient's lower limbs in order to reinforce the desired trajectory in terms of knee position and knee moment along the gait cycle. The proposed system allows for the normal movement of the knee joint along the sagittal plane to allow patient advancement and at the same time incorporates techniques to prevent hyperextension often displayed by these individuals.;A novel actuation mechanism called the Gear Bearing Drive (GBD) developed at Northeastern University is used to drive the AKROD. The Gear Bearing Drive is a compact and light weight system capable of delivering power equivalent to a conventional actuator but is 1/8 smaller in volume. A second version of the AKROD is designed using a brushless DC motor and a planetary gearbox to evaluate the design, torque delivery and other parameters that influence the performance of the brace. Position and impedance control techniques has been developed and implemented on a test bed system and have successfully evaluated and quantified the performance of the actuator to mimic the human gait pattern.