This paper presents a haptic interface with modular linear actuators that addresses the limitations of conventional devices based on rotary joints. The proposed haptic interface is composed of parallel linear actuators that provide high backdrivability and small inertia. The performance of the haptic interface is compared to those of conventional mechanisms in terms of force capability, reflected inertia, and structural stiffness. High stiffness, large range of motion, and high force capability, which are in trade-off relationships in traditional haptic interfaces, are achieved. The device can apply up to 83 N continuously, i.e., three-fold more than most haptic devices. The theoretical minimum haptic force density and stiffness of the proposed mechanism are 1.3 to 1.9 and 37 times those of the conventional mechanisms under similar conditions, respectively. The system is scalable because the structural stiffness depends on only the timing belt stiffness, whereas that of conventional haptic interfaces is inversely proportional to the cube of the structural length. The modular actuator enables changes in the degrees of freedom (DOFs) for different applications. The proposed haptic interface was tested through an interaction experiment in a virtual environment with virtual walls.
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Transparent, High-Force, and High-Stiffness Control of Haptic Actuators with Backlash
Haptic actuators employing speed reductions display desirable increased force capability but have difficulty producing feelings of free space motion due to friction and inertia magnification implicit to actuator dynamics. This work describes a control topology that enables geared haptic actuators to produce highly transparent free space motion when combined with backlash nonlinearities. While the presence of backlash enables the proposed free space motion control, it is also a source of instability, limit cycles, and to some extent rendering distortion. We introduce a smoothed gain scheduling function to mitigate limit cycling and expand the range of stable impedances that can be rendered. The introduction of a design metric called the free space envelope provides a framework to evaluate the effectiveness of the free space controller. Together these two control approaches enable transparent free space, high-force, and stable haptic interactions in systems with backlash, a characteristic common in many speed reducers.
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- Award ID(s):
- 1830516
- PAR ID:
- 10506237
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3503-9993-6
- Page Range / eLocation ID:
- 439 to 445
- Subject(s) / Keyword(s):
- Backlash Transparency Stability Haptic Actuators
- Format(s):
- Medium: X
- Location:
- Delft, Netherlands
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/WHC56415.2023.10224471
