Can overground walking training with a robotic servo-assistive walker versus conventional overground walking training improve walking performance in patients affected by subacute stroke.

Walking training performed by a servo assistive robotic walker supervised by a physiotherapist for 20 sessions (40 minutes per session), 5 times for week for 4 weeks + conventional physiotherapy. Conventional physiotherapy (20 sessions, 40 minutes per session, 5 times for week for 4 weeks) involves exercise for trunk, hand recovery, exercise for tone control, exercise to improve global ability. The overall duration of the intervention is 4 weeks and sessions are administered in one-one mode. The i-Walker is registered as medical electrical equipment in Spain (reg. Number 477/13/EC). The i-Walker s a robotic rollator that integrates sensors and actuators. It uses a standard 4-wheeled Rollator AD100 walker frame sized 500mm (W) x 600mm (L) x 850mm (H) modified for this purpose. Actuators are two hub motors, 100mm diameter, integrated in the rear wheels and are used for braking or helping the user. It is composed also by two modified handlebars with brake handle and force measurement; 32 strain gauges mounted in 8 bridges to measure handlebar forces and normal wheels forces, sensors are arranged in the frame to detect forces, tilt and movement, and an integrated battery supplies power. Services provided by the i-Walker are: (i) active motor assistance to compensate lack of muscle force on climbs; (ii) active brake assistance to compensate lack muscle force on descents; (iii) active differential assistance to compensate asymmetric muscle force; (iv) recording of sensor measurements and actuators activities for later evaluation. During the study we only used the service number 3 named “Active differential assistance to compensate unbalanced muscle force”. During training the amount of assistance (i.e. braking force in each hand) was reduced by the team following this principle: (i) assistance as needed; (ii) a progressive assistance reduction; (iii) safety concerns; (iv) patients ability to drive the device; (v) the affected leg and arm increase of spasticity.