Introduction Available robot-assisted stroke rehabilitation systems are often limited in their utilization in the home environment, due to several barriers such as high cost, absence of therapists, tedious training tasks, or encumbering interfaces. This paper presents a low-cost robotic rehabilitation and assessment device for restoring wrist function, offering wrist exercises incorporating pronation-supination and flexion-extension movements. Furthermore, the device is designed for the assessment of joint stiffness of the wrist, and range of motion in two degrees of freedom. Methods: Mechanical/electrical design of the device as well as the control system is described. A preliminary evaluation focused on the measurement of the torsional stiffness of the limb is presented. It is evaluated by reconstructing the known stiffness values of torsional springs by measuring the motor current required to displace them. Results The device demonstrates the ability to determine the stiffness of an object with low-cost hardware. Use case scenarios of the device for training and assessment of the wrist are presented, allowing for a range of motion of [Formula: see text] and [Formula: see text], for pronation-supination and flexion-extension respectively. Conclusion The device shows potential to help objectively quantify the stiffness of the wrist movement, which consecutively could be used to represent and quantify the degree of impairment of patients after stroke in a more objective manner. Further clinical study is necessary to examine this.

This paper presents a robotic wrist rehabilitation device that facilitates both pronation/supination and flexion/ extension movements. Further, it provides technologyaided assessment capabilities through measurement of joint stiffness, range of motion (ROM) and detection of the catch that is often associated with spasticity. The mechanical and electrical system design, allowing for aforementioned training and assessment capabilities, is presented. An indirect torque measurement via the actuator currents is proposed, which can determine the angle of catch, and compared to the already established methods of using inertial measurement units. The approach is tested using a simplified, mechanical model of the joint catch on the presented device. The results show that the indirect measurement has similar performance of assessing the angle of catch as the inertial data. Therefore, the presented device shows a potential to assess not only stiffness but also the angle of catch without additional sensors.