Due to aging of the population, growing numbers of people are affected by impairments of their motor system, caused by disorders like stroke. Treatment of stroke patients is very intensive in the amount of training per patient per day. The treatment duration per patient combined with the total number of people suffering from a stroke makes rehabilitation therapy extremely costly. This makes devices that could reduce the costs of therapy attractive to rehabilitation centres. Currently there are robotic rehabilitation devices under development for both the upper and lower extremities. Our group focuses mainly on the recovery of gait after stroke. The LOPES robot is designed for use in training on a treadmill to accommodate for limited space of rehabilitation centres and easy access for the therapist to the patient. As a 'robotic therapist' it is meant to make rehabilitation more effective for patients and less demanding for therapists.