This paper is focused on the development of a control system, implemented on a parallel robot designed for the lower limb rehabilitation of bedridden stroke survivors. The paper presents the RECOVER robotic system kinematics, further implemented into the control system, which is described in terms of architecture and functionality. Through a battery of experimental tests, achieved in laboratory conditions using eight healthy subjects, the feasibility and functionality of the proposed robotic system have been validated, and the overall performance of the control system has been studied. The range of motion of each targeted joint has been recorded using a commercially available external sensor system. The kinematic parameters, namely the patient’s joints velocities and accelerations have been recorded and compared to the ones obtained using the virtual model, yielding a very small difference between them, which provides a validation of the RECOVER initial design, both in terms of mechanical construction and control system.

The present study highlights the advantages of robotic systems for post-stroke rehabilitation of the upper limb. The latest demographic studies illustrate a continuous increase of the average life span, which leads to a continuous increase of stroke incidents and patients requiring rehabilitation. Some studies estimate that by 2030 the number of physical therapists will be insufficient for the patients requiring physical rehabilitation, imposing a shift in the current methodologies. A viable option is the implementation of robotic systems that assist the patient in performing rehabilitation exercises, the physical therapist role being to establish the therapeutic program for each patient and monitor their individual progress. Using a set of clinical measurements for the upper limb motions, the analysis of rehabilitation robotic systems provides a comparative study between the motions required by clinicians and the ones that robotic systems perform for different therapeutic exercises. A critical analysis of existing robots is performed using several classifications: mechanical design, assistance type, actuation and power transmission, control systems and human robot interaction (HRI) strategies. This classification will determine a set of pre-requirements for the definition of new concepts and efficient solutions for robotic assisted rehabilitation therapy.