This paper proposes haptic data quantization in communication systems in which all haptic information is transmitted through a network. From an engineering view point, bilateral control with master and slave manipulators has been studied to reproduce kinesthetic sensations. However, in scaled haptic transmission applications, communication constraints are a serious problem especially in a microspace. Moreover, communication delay deteriorates the performance of haptic sensation transmission when a large amount of data flows into a communication line. To reduce the communication delay caused by the amount of information and communication constraints, a data quantization method is discussed. Along with audio and visual information, an encoding technique is often applied to haptic information. In particular, a delta-sigma modulator based on a static quantizer has low computational complexity, and it reduces the quantization error in a low-frequency domain. Therefore, haptic sensation transmission with the modulator is constructed in quantized scaling-bilateral control. According to the analyses of hybrid parameters including the interference of a quantization error and a communication delay, the performance of haptic sensation transmission is evaluated. In experiments with a communication delay, stable operation and improved performance are achieved to reduce all information: current, position, and force.
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