Not sure what degrees of freedom are but any research into this is good.
http://gradworks.umi.com/34/87/3487075.html
Abstract:
Prior research has shown that high-intensity repetitive movement training is an effective method for restoring some function to patients with chronic hemiparesis resulting from a stroke. The goal of this dissertation was to develop and evaluate a robotic system for assisting in post-stroke upper-extremity rehabilitative physical therapy. The primary contributions of this research are in: the development of control software for a rehabilitation robot; the development of a virtual environment for rehabilitation; the integration between a robot controller and a virtual environment; the design and analysis of an algorithm for maintaining a challenging level of therapy; and a clinical trial testing the efficacy of functional multi-joint movement therapy (FMJMT) versus isolated individual joint movement training (IIJMT).
The robotic mechanism created to provide therapy is a 6 degree-of-freedom (DOF) pneumatically actuated exoskeleton, which included a 3 DOF shoulder, a 1 DOF elbow, and a 2 DOF module for forearm supination/pronation and wrist flexion/extension. The shoulder is driven by redundant actuation of a novel spatial parallel mechanism. The elbow, forearm, and wrist are all actuated in serial with four-bar slider-crank mechanisms.
The virtual environment consisted of several games with point-to-point reaching or continuous tracking tasks. Some of the games required squeezing a pressure sensitive device for grasping items in the games. There was also another novel environment that allowed for a coordinated movement strength assessment. An algorithm that was developed to discretely alter the game difficulty was implemented in some games to maintain a challenging level of therapy for the patients. This algorithm is also shown to detect motor improvement.
The clinical trial involved a crossover design study with 20 patients who had chronic hemiparesis after stroke. Of these, 10 patients received FMJMT for 3 one hour sessions per week for 4 weeks followed by IIJMT for the same duration. The other 10 subjects received both interventions in the opposite order. The results from the study indicated both training techniques promoted motor recovery with slightly more benefit from IIJMT suggesting that the complexity of multi-DOF robots may not be necessary for promoting upper limb recovery in hemiplegic stroke survivors.
Degrees of freedom is the number of motions a joint can perform. For example, the elbow has two degrees of freedom because it can bend and straighten. I'm not wild about electronic devices that let a client slack off and let the device do the work. I've had to work like a maniac to get back every movement.
ReplyDeleteI'm the author of this dissertation and would like to clear up a few things.
DeleteDegrees of freedom describes the number of independent parameters necessary to define the position of the system. An elbow only has 1 degree of freedom because there is a single axis of rotation. Direction of motion is irrelevant to the number of degrees of freedom.
If you ignore trunk motion, the human arm has approximately 9 degrees of freedom up until the hand (2 resulting from movement of the clavicle, 3 at the glenohumeral joint (shoulder), 1 at the elbow, 1 in the radioulnar joint (forearm), and 2 in the radiocarpal joint (wrist)). This robot does not have movements related to abduction/adduction of the wrist or related to clavicle motions.
This particular robot does not let the patient slack off. If the patient is not working with the robot, it will not be able to perform the desired activities. However, if the patient is working towards a prescribed goal, the robot will be able to assist them in achieving it. We've done this by programming the robot to be more of a "slacker" than the patient. The idea is that as long as the patient is putting in effort, letting them see results they otherwise couldn't achieve will be motivating to continue their therapy. Of course as Rebecca pointed out, some devices don't implement "slacking" and really aren't very beneficial. For more on slacking, reading some papers by Dr. David J. Reinkensmeyer is a good start.
Lastly, I wish you both the best in your recoveries. Working on this project, I got to see how much of a struggle it is for people trying to overcome their neurological injuries. Although sometimes pushing until they were red in the face, the patients seemed to enjoy their time with the robot and the wonderful therapists who were operating it. Keep up the hard work.