Brushless DC Motors Used in Industrial Exoskeletons

update:2023-05-10

abstract:"Industrial exoskeletons"is the collective name given to mechanical devices worn by workers, whose c...

"Industrial exoskeletons"is the collective name given to mechanical devices worn by workers, whose construction mirrors the structure of the operator’s limbs, joints, and muscles, works in tandem with them, and is utilized as a capabilities amplifier or as a fatigue and strain reducer. With some exceptions, industrial exoskeletons are able-bodied devices designed to augment workers performing specific, repetitive physical tasks. They are the opposite of medical exoskeletons, which focus on individuals who have lost some physical capability.

As the exoskeleton sector continues to evolve, the medical, business and technical press has long reported on exoskeleton technologies designed for medical rehabilitation and mobility aids, even though commercial success and large-scale adoption have not yet been realized. Sometimes referred to as exosuits, exoskeletons are wearable machines suited with motorized joints that provide lift support, weight dispersion, posture correction, and other capabilities to minimize strain and injury.

These machines are mainly used for physical rehabilitation but are increasingly used by workers in construction and manufacturing. It takes the weight of users’ arms off their necks, backs, and shoulders and transfers it to their cores. The energy that workers expend becomes more evenly distributed, which reduces strain and stress on the muscles and joints.

Commonly use miniature brushless DC motors with additional products such as gearboxes for attaining high torque and encoders for positional feedback. Some models shift weight from one part of the body to other areas to reduce continuous strain and increase endurance, while others use grasping tools to enhance a user’s strength.

In this sense, exoskeleton technology can be seen as a bridging solution between the extremes of fully manual work and those tasks that demand typical industrial robots. Just as model-based control relies on physical models of the dynamics and contacts of the system (exoskeleton and human) to determine the actuation of the motors. Only a few controllers compensate for the complete exoskeleton dynamics, which requires a fully dynamic model of the exoskeleton.

The output of these model-based controllers is the torque needed at each joint. The widely used Series Elastic Actuators (SEA) facilitate torque control with a spring(like) element with the actuator. Thus acting as a buffer for the impact that can reduce the actuator inertia felt by the user.

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