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G. Niemeyer, N. Diolaiti, N. Tanner
"Wave Haptics: Encoderless Virtual Stiffnesses"
Type Conference
Author(s) G. Niemeyer, N. Diolaiti, N. Tanner
Title Wave Haptics: Encoderless Virtual Stiffnesses
Editor ISRR 2005: International Symposium of Robotics Research
Keywords Haptics, Wave Variables, Virtual Coupling, Motor Dynamics
Haptic rendering generally uses DC motors with current amplification and encoder measurements to implement virtual springs. Quantization of position signals and delays in the amplifiers due to undesired electrical dynamics impose practical limits that have triggered much research effort. We present an alternate approach that fully embraces and utilizes all electrical dynamics as part of the actuator. In particular, the electrical inductance L serves as a stiffness that couples the virtual environment to the user. We further build a wave transformation from the motor resistance R. Implementing virtual objects in a wave domain provides robustness to servo delays. Only a simple voltage drive circuit is necessary to operate the proposed scheme. The resulting system not only simplifies amplifiers, but substantially outperforms traditional approaches. The coupling between virtual and real domains is build entirely from physical elements and does not require encoder feedback. The achieved stiffness exceeds existing values. The remaining unmodeled dynamics of transistor switching fall far beyond human perception capabilities. A prototype system has been implemented and confirms the promise of this novel paradigm.
Year 2005

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