Recently, various assistant devices for physically handicapped persons in the rehabilitation robotics research area have been studied. The real issues in the design of the assistant devices are the directly human-device coupled design, the ease-to-use, and the portability. As part of resolving these issues, this paper presents the foundation works on sensor and actuator effectively applicable to the wearable haptic master device for the disabled.
Sensors developed in this study consist of optical fibers. Their flexibility, lightness, small size, and low cost can yield the wearable master device for the disabled. The test apparatus is developed for possibility of making the wearable master device especially on shoulder. Both of the bending direction and amount of bent angle with one optical fiber curvature sensor are measured to use its primary features. To predict 2 DOF shoulder motion by using two optical fiber sensors, calibration method and mapping function are developed. Sensor map for direction classification of shoulder motions is framed and mapping function for more accurate estimation is developed by finer interpolation between calibration points. Experimental results show good performance of the sensors by using the proposed calibration method and mapping function.
In addition, vibrotactile actuators are developed to feedback the contact force to the skin. Tactile-force substitution is adopted for this purpose. Experimental results confirm that the tactile-force substitution improves the efficiency of the task dealing with objects and the frequency or magnitude of the vibrotactile stimulus should be corresponded exponentially for the linearly increasing human perception.
