Skip to main content Skip to navigation
Robotics and Automation Lab MR-brake with magnets

MR-brake with magnets

MR-brake with permanent magnets


A new magneto-rheological brake that uses only permanent magnets to produce variable torque output. A magnet array was developed that can be operated by a tiny motor allowing the device to apply 1.8 Nm torque using only 1.4 W of electrical power.

The new MR-brake does not use any coils. It only requires power when changing the torque output. It can operate for 22 hours using a small battery while cycling through full on/off torque output. It can also apply full torque output indefinitely with no power input required to keep it on. There is no joule heating since there are no coils in the design.


The device uses an array of eight permanent magnets (item #6 below), which are rotated by the small motor to create variable flux inside the brake.




  • “Magneto-rheological actuator with permanent magnets for low-power activation,” Journal of Intelligent Material Systems and Structures, Vol. 31 Issue 6, pp. 801-817, September 2020.