Technical Development of a Lower-Limb Therapy Device for Bed-Resting Users

Patients with neurological disorders require bed rest due to impaired lower limb function. The aim of this work was to develop and evaluate an in-bed lower-limb therapy device that provides various training patterns for the foot and leg with an intuitive user interface and interactive exergames. Based on clinical interviews, the user requirements for the device were determined. The therapy device consisted of two compact foot platforms with integrated electric motors and force sensors. Motion control algorithms and a user interface with computer games were developed. Through a touch screen, the target force and position were defined. Using automatic position and force control algorithms, the device could produce leg flexion/extension, synchronised plantarflexion/dorsiflexion, and leg pressing with active loading. An evaluation test on 12 able-bodied participants showed that the device produced passive (position control errors: 18.96 mm linearly, and 2.27o in the ankle joints) and active leg training (force control error: 6.98 N). The computer game was demonstrated to be interesting, engaging and responsive to the training movement. It was concluded that the portable in-bed lower-limb therapy device managed to provide various training patterns with satisfactory accuracy and the users were encouraged by the exergame to practise with active participation.