The most important thing in a thin and soft haptic module with an electroactive polymer actuator array is to increase its vibrotactile amplitude and to create a variety of vibrotactile sensations. In this paper, we introduce a thin film-type electroactive polymer actuator array capable of stimulating two types of human mechanoreceptors simultaneously, and we present a haptic rendering method that maximizes the actuators’ vibrational force without improving the array’s haptic performance. The increase in vibrational amplitude of the soft electroactive polymer actuator array is achieved by creating a beat vibration, which is an interference pattern of two vibrations with slightly different frequencies. The textures of a target object are translated into haptic stimuli using the proposed method. We conducted qualitative and quantitative experiments to evaluate the performance of the proposed rendering method. The results showed that this method not only amplifies the vibration’s amplitude but also haptically simulates various objects’ surfaces.

In interactive Internet of Things (IoT) environment, a solenoid-based tiny pin-array tactile device can become a key module to haptically simulate a surface of interconnected objects. The solenoid-based pin-array tactile device creates a large enough force and stroke to stimulate human skin and generates a wide frequency range. The solenoid-based tiny pin-array tactile device, however, brings a new issue of controlling the pin’s stroke of the tactile device. To overcome the limitation of the solenoid-based device, a new tactile rendering method is needed. In the proposed tactile rendering method, we control the operating frequency of pins, instead of controlling their stroke, to haptically simulate the surface of interconnected objects. Our experiments demonstrate that our proposed method with a pin-array tactile device is suitable for simulating the surface of interconnected objects.