Upper Limb Robotic assisted Rehabilitation in Stroke Patients · Upper Limb Roboticassisted Rehabilitation in Stroke Patients ... but the training they have to undertake for safely

Upper Limb Robotic­assisted Rehabilitation in Stroke Patients Antonio Frisoli1, .Edoardo Sotgiu1, Massimo Bergamasco1, Bruno Rossi2, Carmelo Chisari2, Maria C. Carboncini2 

1. PERCRO Laboratory, Scuola Superiore Sant’Anna, Pisa 

2. Neurorehabilitation Unit Department of Neurosciences Azienda Ospedaliera Universitaria Pisana Pisa Italy 

Abstract In the last decade a very important and impacting topic for research has concerned the development of strategies and technologies addressing the improvement of stroke rehabilitation and the reduction of its costs. Actually there has been a strong burst in robotics rehabilitation, aiding the physical rehabilitation process based on exercises carried out in virtual environments. Many studies have shown the importance of intensive and timely rehabilitation interventions for achieving successful results in terms of disability containment and functional recovery. This has raised further issues in terms of costs and availability of rehabilitation facilities also in terms of therapists availability. Again rehabilitation robotics and virtual rehabilitation have proved to be an effective solution to face these problems, while also introducing motivational stimulus for the patients who have to stand long and intensive exercise practice.

The Light-Exoskeleton Rehabilitation system (Lexos) aims at the development of new therapy proposals of robotic-assisted rehabilitation in Virtual Environments and the assessment of their efficacy for the regaining of upper limb function after motor impairments due to neurological lesions. The target populations consists mainly of adult patients with motor impairments following stroke in the chronic phase. The presence of the rehabilitation therapist is ever required, but the training they have to undertake for safely and effectively using the system is easy and rapid, not requiring any special competence in robotics, computer science or virtual reality applications, and each therapist may follow more than one patient.

Figure 1: Lexos Rehabilitation platform (left) and Light Exoskeleton device (right). 

The Lexos system is composed of a force-feedback right-arm robotic system with anthropomorphic kinematics with 5 degree of freedom (DoF): four of them fully actuated, while the last one is a passive joint and used to measure the wrist prono/supination motion. The Lexos can so provide the required kinesthetic feedback to the arm patient for performing the rehabilitation task, performing continuous force at the patient hand of 50N, and 10Nm of torque at each joint. A three-axial sensor and two pressure sensors mounted at the handle are included for registering the proximal activities

 during the rehabilitation session. The type of controller is based on nonlinear sliding control in several modalities: active position, passive position, assisted posture control by exerted force and direct force control. The system is integrated with a virtual reality system providing different scenarios where the patient may perform customized exercises requiring specific 3D movements. The exercises already included in the Lexos “product package” concern the reaching tasks (Reaching) and an object manipulation tasks (Cubes). All the parameters of the virtual scenarios can be easily adjusted in real-time by the therapist through a Graphical User interface.

Figure 2: Reaching task (left) and manipulation task (right). 

Furthermore several other parameters can be set as the: • passive, active and assisted arm posture control (Reaching); • selective joints constraint (Reaching); • partial or total patient’s arm weight compensation; • viscous resistance force (Cubes).

During the reaching task a visual feedback allow the patient to know the resistance torque made at each joint and the force resistance applied at the handle. During the manipulation task the visual feedback is represented by a bar showing the grasping force applied on the handle; at the end of each session the total time spent to finish the exercise.

The Lexos is currently used in experimental campaigns on selected clinical patients undertaking a special clinical protocol for post-stroke motor rehabilitation at the Neurorehabilitation unit of Cisanello hospital in Pisa.