Shun Ishikawa

Wearable dummy to simulate joint impairment: severity-based assessment of simulated spasticity of knee joint

Physical therapists master manual examination techniques for testing impaired motor functions. We used a wearable robotic dummy joint that simulated disordered joint resistances to help physical therapists learn such techniques. This study developed a resistance model for a spasticity joint, and the dummy joint was used to present it. We assessed the simulated spasticity model using Modified Ashworth Scale (MAS), which is an evaluation criterion for spasticity seriousness that is widely used by physical therapists. The results of experiments involving two physical therapists showed that the model accurately expressed mild-to-severe symptoms of knee joint spasticity. It is expected that using the system in educational institutions for physical therapists will help students learn the typical levels of joint resistance caused by spasticity with different degrees of severity.

Wearable dummy to simulate joint impairment: Model for the discontinuous friction resistance due to arthritis

Physical therapists master manual examination techniques for testing impaired motor functions. We developed a wearable robotic dummy joint to simulate disordered joint resistances for supporting physical therapists to learn such techniques. A model to simulate discontinuous joint friction resistances due to diseases such as osteoarthritis was developed. Because such resistance originates from abnormal frictions of bones and cartilages, we used a stick-slip model to simulate the resistances. The model was validated based on the introspection of physical therapists. This study concludes that a discontinuous friction model presents forces that are perceptually similar to those typically caused by damaged or roughened joint cartilages.

Spectrum-based synthesis of vibrotactile stimuli: active footstep display for crinkle of fragile structures

When a human crinkles or scrunches a fragile object, for which the yield force is very small that it is hardly perceived, they identify the material of the object based on tactile stimuli delivered to the skin. In addition, humans are able to recognize materials even when they are crinkled at different speeds. In order to realize these human recognition features of the crinkle of a fragile object, we develop a vibrotactile synthesis method. This method synthesizes the vibrotactile acceleration stimuli in response to a crinkle speed based on the preliminarily measured acceleration spectra. Using this method, we develop an active footstep display that presents a virtual crinkle of fragile structures made of different materials to its users. Experimental participants could identify three of the four types of virtual structure materials at rates significantly higher than the chance level. The four materials were copy and typing paper, aluminum foil, and polypropylene film. Furthermore, the trends of answer ratios exhibit good correspondence with those for the real cylindrical fragile objects. We conclude that the developed method is valid for the virtual crinkle of fragile structures and will enhance the validity of virtual reality systems, such as a virtual walkthrough system.

Assessment of Robotic Patient Simulators for Training in Manual Physical Therapy Examination Techniques

Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard.

Simulated crepitus and its reality-based specification using wearable patient dummy

Physical therapists are trained in manual examination techniques to test the impaired motor functions of patients. In this study, we have introduced a wearable robotic dummy joint to simulate disordered joint resistances or behaviors to support physical therapists in learning such techniques. We developed a discontinuous joint friction model based on a stick-slip phenomenon to simulate knee joint resistances caused by crepitus, a typical symptom accompanied by osteoarthritis. Practicing therapists participated in a reality-based evaluation test and specified acceptable parameter sets to adjust the simulated crepitus for the exoskeletal patient robot. The simulated crepitus and wearable dummy joint are expected to support the training of physical therapists. Graphical Abstract

Exoskeleton Simulator of Impaired Ankle: Simulation of Spasticity and Clonus

We developed a prototype of an exoskeletal patient simulator that allows clinical trainees to experience and learn about ankle disorders related to hemiplegia. The exoskeleton exerts abnormal joint torques by tendon mechanisms while realizing complex ankle movements and realistic bone and skin features. Using this exoskeleton, we simulated the resistances of spasticity and clonus, which are typical symptoms of hemiplegia. We demonstrated these two types of simulated symptoms and showed their validity.

Wearable Robot for Simulating Knee Disorders in the Training of Manual Examination Techniques

This study addresses a haptic simulator of diseased knee joints that is intended for the use in the training of manual examination techniques used in physical therapy. These techniques involve clinicians moving the impaired joint of a patient to test the dynamic joint resistance caused by a condition. Our exoskeleton robot simulates five types of common knee problems. The simulated symptoms were checked in terms of subjective similarity to actual symptoms that physical therapists experience in their work. Three of the five symptoms could be correctly identified, whereas the other two were found to require further tuning. The proposed patient simulator could improve the training of manual examination techniques by being able to simulate a variety of symptoms.