Control for high frequency rendering on impedance type haptic devices
- Robotic haptics is a growing field that uses specially designed robotic devices as force-reflecting, human-computer interfaces in a variety of applications, from 3D modeling and gaming to telerobotic controllers and surgical simulation. While many types of haptic devices have been prototyped and studied, small, back-drivable, desktop devices such as the 3D Systems Phantoms and Force Dimension Omegas are by far the most common due to their commercial availability, relatively low cost, safety, and ease of use. However, stable and accurate rendering of high frequency signals on these impedance type haptic devices remains a challenge. Traditional control techniques rely on digital closed loop position feedback, which is not well suited to handling the high frequencies inherent in rigid contact simulation and the display of vibrations, transients, and textures. Further, the complex high frequency dynamics of the device act to distort and couple high frequency, multi-degree-of-freedom signals. In this dissertation, three control strategies are presented that improve the performance of impedance type devices at high frequencies, particularly during rigid contact simulation. The first utilizes a high bandwidth current loop at the motor amplifier level to add significant impedance to the device by leveraging the motor dynamics. This enables much higher stiffness rigid contacts, but requires a new high-level control framework for practical implementation. The second strategy layers on top of existing controllers and aims to provide a perception of rigid contact by stopping a user's momentum as quickly as possible through use of an impulse-generating switching controller. Finally, distortion and cross-coupling of high frequency signals are improved through a deconvolution-based, multi-DOF haptic device equalizer.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Mechanical Engineering.
|Salisbury, J. Kenneth
|Salisbury, J. Kenneth
|Statement of responsibility
|Submitted to the Department of Mechanical Engineering.
|Thesis (Ph.D.)--Stanford University, 2017.
- © 2017 by Robert Patrick Wilson
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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