Limitations of human 3 d-force discrimination

Internet-based telepresence and teleaction systems require packet-based transmission of haptic data and typically generate high packet rates between operator and teleoperator. This leads to the necessity of packet rate reduction techniques. The so-called deadband approach presented earlier by the authors uses a psychophysically motivated scheme based on Weber’s difference threshold (just noticable difference JND) where force sample values are only transmitted if the change exceeds this threshold. This approach has been extended to three dimensions resulting in an additional perceptual domain namely force direction. An experimental evaluation with human subjects was conducted in order to examine the change of the JND in 3D when force magnitude and force direction are combined. Our results show that the extension into dimensions yields to an increased JND in certain cases. Thus, higher compression ratios of haptic data and reduction in number of packets sent over the network can be reached.