Intervention (if applicable): Haptic feedback of the I-TRAVLE robot either supports or challenges the patient to perform movements of the arm, thereby training motor control and co-ordination of the affected arm. Also strength and endurance of arm muscle use may be trained. The I-TRAVLE based training will last 6 weeks. Each week participants will attend training sessions on 3 days, during which they will train 2x 30 minutes, interspaced by at least half an hour to avoid (general) fatigue and overuse.