Motion control of impedance-type haptic devices

Impedance type devices are frequently used in haptics due to their excellent rendition of free-space, low cost, and convenience. The spring drive, a recently proposed alternative to the traditional current motor driver for such devices, has been shown to improve their stiffness in rigid contact by moving the haptic coupling from the digital domain to analog circuitry. Unlike the current drive, which operates the motor as a force source, the spring drive converts the motor to a motion source. In this paper we construct a motion-based virtual environment to fully leverage the benefits of operating an impedance device with motion control. This quasi-static environment is connected to a mid-level controller which interfaces with the analog motor drive. A full system analysis and experimental demonstration verify the anticipated performance.