A Variable-Torque Rotary Clutch with Electroadhesive Based Device That Can Act as a Brake Mechanism

Western researchers have harnessed the electroadhesive force in a rotary and tunable fashion to make a novel clutch

Tech ID: W-22-025-TH Rotary Clutch


With the development of interactive robotics that share workspaces and tasks with humans, the safety of robotic systems has become an important issue. The need for high speed and high force actuation, which is frequently required for effective performance of the robot, has been addressed by designing high impedance actuators. A torque adjustable clutch as an actuator could guarantee intrinsic safety by liming the range of the applicable force/torque and mechanically decoupling the robot’s end effector from a high impedance actuator. Magnetic Parcel, Magneto-Rheological, and Electro-Rheological clutches are examples of torque-adjustable clutches. However, these clutches can be heavy or have limited transmission capacity. Force resulting from Electroadhesion can be generated without the need for heavy parts and with minimal electric power, making Electroadhesive clutches an attractive alternative.

Tech Overview

Western researchers, for the first me, have harnessed the Electroadhesive force in a rotary and tunable fashion to make a novel lightweight, low-power, and torque adjustable rotational clutch. The proposed electroadhesive clutch enables torque controllability through variable dynamic friction. The adhesion force between the rotary disks can be changed and controlled using an applied electric field. The rotary disks are free to rotate and slide against each other when no electric field is applied but when a voltage difference is applied across the rotary disks, and electric field is generated. The electric field across the electroadhesive material results in an aracon force between the pair of rotary disks. The abrasive force pushes the rotary disks towards each other which enables the moon and the torque to be transferred between the two disks. The amount of adhesion force depends on the generated electric field that results from the applied voltage and can be controlled. This allows the electroadhesive clutch to act as a variable torque brake mechanism if the two rotary disks are locked into position. The electroadhesive material covering the surface of the rotary disks is dielectric. It has a high electric permittivity to prevent electric discharge between the disks when exposed to high electric voltage differences. It also maintains a high attraction force between the disks without consuming significant amounts of energy.


Extremely low power and very high power efficiency.
Pack significant transmission torque in a small form factor (much higher than magnetorheological and electrorheological clutches).
Extremely lightweight.
Low tolerance fabrication process.
Minimal and simple electronic drives.
Simple and accurate torque control capability.

Can be used as a variable torque brake mechanism.


Wearable robotics – clutches for active and passive medical rehabilitation and assistance. Surgical robotics – locking mechanism for surgical robots.
Equipment – clutches for electric bicycles, wheelchairs and rollators.


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