In robotics and haptics, actuators that are capable of high force output with compact size are desired for stable and stiff interfaces. Magnetorheological brakes are viable options for such implementations since they have large force-to-volume ratios. Existing linear magnetorheological brakes have limited strokes, are relatively large, and have high off-state friction forces mainly due to the piston-cylinder internal design.
The main contribution of this research is a new alternative internal design for linear magnetorheological brakes. It leads to significantly less off-state friction and infinite stroke. To the best of our knowledge, this was the first such linear magnetorheological brake. Our new brake can produce 173-N force. In comparison, a conventional linear magnetorheological brake with the same size can only produce about 27-N force.
The design uses the serpentine flux path concept to eliminate the piston-cylinder arrangement.
United States Patent: Linear MR-Brake as a High Force and Low Off-state Friction Actuator, U.S. Patent 9,109,650 B2, August 18, 2015
- “Linear magnetorheological brake with serpentine flux path as a high force and low off-state friction actuator for haptics,” Journal of Intelligent Material Systems and Structures, vol. 24, no. 14, 2013.
- “Control strategies for a linear MR-brake with serpentine flux path for haptics,” Proceedings of ASME 2012 Biennial Conference On Engineering Systems Design and Analysis ESDA 2012, Nantes, France, July 2012.