Embedded corrective force cueing: A force-feedback control design to optimize the motivating potential of robot-assisted therapy devices to increase bilateral functioning in hemiplegic stroke patients

This dissertation presents a new design method, Embedded Corrective Force Cueing (ECFC), a device-based stroke therapy method for motivating increased use of the impaired upper limb in bilateral tasks. This method aims to reduce upper limb physical dysfunction due to hemiplegia, a common disability affecting about 75% of stroke survivors. The ECFC strategy aims to create robot-assisted therapy devices that provide powerfully motivating reasons for stroke survivors to use their impaired arm in activities of daily living requiring bilateral arm use. At the center of ECFC strategy is corrective force cueing, a novel use of force-feedback control that uses force cues to actively restrain the stronger unimpaired arm from compensating for impaired arm. It is hypothesized that corrective force cues can increase the motivation of stroke survivors to use their impaired arm more when it is embedded into an activity that is both meaningful and purposeful to the stroke survivor and when it is implemented to dynamically create a functional need for the impaired arm in the activity. This control method builds on motivation and behavioral psychology principles found in successful stroke treatment techniques such as constraint-induced therapy.; Driver's SEAT (Simulation Environment for Arm Therapy), a one degree-of-freedom robot-assisted therapy device, is an environment that implements the ECFC strategy in one of its three steering modes. Results from controlled experiments, where persons with hemiplegia used Driver's SEAT to complete bilateral and unilateral steering tasks under conditions with and without corrective force cues, support the hypothesis. The presence of the force cues caused significant increase in the use of the impaired arm in bilateral tasks during segments of the steering task where subjects tried to compensate using the unimpaired arm.; This thesis outlines a design framework, which is composed of five design principles. This framework is a design strategy that can be used to create more functional and highly motivating robot-assisted stroke therapy environments. Analysis of a representative set of robot-assisted therapy environments and results from an interview-based study on the clinical utility of Driver's SEAT support the validity of the design principles and the ECFC control strategy.