Haptic displays have been developed to provide operators with rich tactile information using simple structures. In this study, a three-axis tactile actuator capable of thermal display was developed to deliver tactile senses more realistically and intuitively. The proposed haptic display uses pneumatic pressure to provide shear and normal tactile pressure through an inflation of the balloons inherent in the device. The device provides a lateral displacement of ±1.5 mm for shear haptic feedback and a vertical inflation of the balloon of up to 3.7 mm for normal haptic feedback. It is designed to deliver thermal feedback to the operator through the attachment of a heater to the finger stage of the device, in addition to mechanical haptic feedback. A custom-designed control module is employed to generate appropriate haptic feedback by computing signals from sensors or control computers. This control module has a manual gain control function to compensate for the force exerted on the device by the user’s fingers. Experimental results showed that it could improve the positional accuracy and linearity of the device and minimize hysteresis phenomena. The temperature of the device could be controlled by a pulse-width modulation signal from room temperature to 90 °C. Psychophysical experiments show that cognitive accuracy is affected by gain, and temperature is not significantly affected.

In this research, we propose a sensor system consisting of a power-generating sensor with a textile structure comprising piezoresistive, piezoelectric, and supercapacitor threads, and a circuit for efficient energy delivery. A multifunctional piezoelectric energy harvester for energy generation, piezoresistive strain, and capacitive tactile sensors to detect motion, and supercapacitor for energy storage were implemented through the proposed sensor platform. An energy management circuit was also added to the platform to store the generated energy and supply it for sensor operation. The devices were fabricated into a textile structure using functional threads in a total area of 130 mm × 130 mm with a 7 × 7 thread array. The piezoresistive strain sensor exhibited a resistance change of approximately 24% at a maximum strain of 24%, and the capacitive tactile sensor exhibited a change rate of 12.5% at a maximum vertical force of 5 N. In addition, the energy source, a piezoelectric energy harvester, obtained a power of 440 μ W at a 6 Hz motion and a 3 MΩ load resistor. In the energy management circuits, using a parallel synchronized switch harvesting on inductor (P-SSHI) circuit and a voltage doubler, increased the voltage stored in the supercapacitor by 119%.