September, 28, 2021

Upper-limb Rehabilitation Robotics

You may have already heard about rehabilitation, or you may have used some of the services in the past, or the first thing that comes to your mind is Britney Spears. But whatever you’ve already had in your mind, rehabilitation refers to enhancing or restoring the movement and quality of life for people with disabilities or other impairments due to diseases or injury.

However, doing repetitive tasks for long periods of time is daunting and less intensive than needed for proper treatment. For this reason, our old friends, robots come in handy here. Robots turn repetitive, dull exercises into more challenging and motivating tasks such as games.   
Robots can also provide a quantitative measure of the rehabilitation progress, and robot-aided rehabilitation is more intensive, of longer duration, and more repetitive. Aren’t you convinced yet? How about this one?

The clinical outcomes of the built rehabilitation robots up to this day demonstrate that rehabilitation robots not only increase the outcomes of rehabilitation but also be used in real-life applications and are totally accepted by the patients.   
With this introduction out of the way, let’s jump right into the topic and see different types of upper-extremity rehabilitation robots.

From the design point of view, upper-extremity rehabilitation robots can be classified into end-effector-based robots and exoskeleton-type robots.   
End-effector-based robots are simple, and the patient’s hand is attached to the handle of the robot to follow a specific trajectory. These types of robots cannot provide a rotation movement and thus are not suitable for pronation and supination movements.

MIT Manus (InMotion) is a five-degrees-of-freedom end-effector-based robot for rehabilitation of the upper limb after a stroke developed by MIT and uses games to increase the rehabilitation outcome. The five dofs of this robot are two translational dofs for elbow and forearm flexion/extension and pronation/supination, and three dofs for wrist flexion/extension, pronation/supination, and abduction/adduction. Impedance control is used to control this robot.

InMotion (MIT Manus) is an end-effector-based rehabilitation robot that uses impedance control and games to increase the outcome of rehabilitation for stroke patients.

Exoskeleton-type upper extremity rehab robots have the same or more degrees of freedom than the human arm, and the robot joints are usually aligned with the human joints. They typically calculate the required torque for each joint and control the limb movements. They are difficult to adapt to different body sizes than the end-effector-based robots and are also not used in bilateral rehabilitation as it is expensive to build right and left exoskeletons for left and right hands.   
ARMin (Armeo Power) is a seven-degrees-of-freedom exoskeleton type robot developed by Nef et al. (and then with Hocoma) with joint limits according to the human limbs. The seven dofs consist of shoulder rotations in 3D, flexion/extension of the elbow, supination/pronation of the forearm, flexion/extension of the wrist, and closing and opening of the hand.

ARMin (Armeo Power), developed by Hocoma, is an exoskeleton-type rehabilitation robot for upper-extremity rehabilitation after a stroke.

CADEN-7 (cable actuated dexterous exoskeleton for neuro-rehabilitation with seven degrees of freedom), T-Wrex: therapy Wilmington exoskeleton (5 dofs), BONES: Biomimetic Orthosis for Neurorehabilitation (4 dofs), L-EXOS (5 dofs), and REHAROB (3 dof) are some of the other exoskeleton-type rehabilitation robots. 
In conclusion, research shows that robot

- aided therapy indeed had a greater influence than manually-assisted therapy. The intensity of exercises can be increased using VR technology and games that also motivate patients to exercise more.


  1. Babaiasl, M., Mahdioun, S.H., Jaryani, P. and Yazdani, M., 2016. A review of technological and clinical aspects of robot-aided rehabilitation of upper-extremity after stroke. Disability and Rehabilitation: Assistive Technology, 11(4), pp.263-280.
  2. Ren, Y., Kang, S.H., Park, H.S., Wu, Y.N. and Zhang, L.Q., 2012. Developing a multi-joint upper limb exoskeleton robot for diagnosis, therapy, and outcome evaluation in neurorehabilitation. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 21(3), pp.490-499.
  3. Proietti, T., Crocher, V., Roby-Brami, A. and Jarrasse, N., 2016. Upper-limb robotic exoskeletons for neurorehabilitation: a review on control strategies. IEEE reviews in biomedical engineering, 9, pp.4-14.
  4. Fasoli, S.E., Krebs, H.I., Stein, J., Frontera, W.R., Hughes, R. and Hogan, N., 2004. Robotic therapy for chronic motor impairments after stroke: Follow-up results. Archives of physical medicine and rehabilitation, 85(7), pp.1106-1111.
  5. Nef, T., Guidali, M. and Riener, R., 2009. ARMin III–arm therapy exoskeleton with an ergonomic shoulder actuation. Applied Bionics and Biomechanics, 6(2), pp.127-142.