Shoulder exoskeletons are wearable devices that support and augment human shoulder movement. They integrate mechanical and electronic components to amplify, reinforce, or restore physical performance.
How Shoulder Exoskeletons Provide Assistance
Shoulder exoskeletons reduce physical load on muscles, especially during overhead or repetitive tasks. They offload arm and tool weight, compensating for gravity. For example, the Auxivo DeltaSuit transfers load from the upper arm directly to the torso, bypassing the shoulder joint.
This load redistribution alleviates strain on shoulder muscles, common in labor-intensive jobs like construction or manufacturing. By providing assistive torque, exoskeletons reduce muscle activity in areas such as the anterior and medial deltoid muscles, sometimes by 16% and 41% during isometric overhead work. This decreases muscle fatigue and discomfort.
Exoskeleton support allows individuals to perform tasks longer with less perceived exertion and lower cardiac cost. Studies show reductions in cardiac cost by 15%, perceived exertion by 21.5%, and a 57% decrease in shoulder discomfort. This sustained support helps prevent injuries from muscle overload and promotes consistent work performance.
Types and Applications
Shoulder exoskeletons are categorized into passive, active, and hybrid systems. Passive systems, like the CarrySuit or Hilti EXO-S, use mechanical elements such as springs or counterweights for gravity compensation without external power. These lightweight devices, some weighing around 3.5 kg, are common in industrial settings for tasks like overhead assembly, installing drywall, or sanding ceilings, where workers maintain elevated arm positions.
Active exoskeletons incorporate motors or pneumatic systems for powered assistance, offering greater flexibility and adjustable support. They include an embedded real-time controller and on-board motion sensors to intelligently determine and adjust assistive torque based on user movement. For example, an active device might deliver up to 30 Nm of assistive torque. While offering dynamic support, active systems are generally heavier and require a power source.
Hybrid systems combine passive and active designs, balancing support and portability. Beyond industrial use, shoulder exoskeletons assist individuals with limited mobility, such as stroke patients, by guiding and supporting movements during physical therapy. This range of designs offers tailored solutions across sectors, from enhancing worker safety and productivity to facilitating recovery and improving daily living.
Core Technologies
Shoulder exoskeleton functionality relies on sensors, actuators, and a control system. Sensors gather data about user movements and intentions, including electromyography (EMG) sensors measuring muscle electrical activity and force/torque sensors monitoring mechanical loads and joint movements. This feedback is crucial for the exoskeleton to respond appropriately and provide timely assistance.
Actuators generate physical force or torque to assist the user. These range from springs and elastic materials in passive systems to electric motors or hydraulic systems in active designs. For instance, a passive system might use a spring to generate torque, while an active version could use a brushless electric motor. Actuators work by transferring load away from the shoulder or by directly providing a supporting force parallel to human muscles.
The control system acts as the “brain” of the exoskeleton, interpreting sensor data and directing actuators. This system ensures the device provides appropriate assistance, maintains safety, and adapts to user movements in real-time. Advanced control strategies, including machine learning and adaptive control, allow exoskeletons to learn from user behavior and adjust assistance to optimize performance and user experience.
Practical Considerations for Users
For users, fit and comfort are paramount. The device must be ergonomically designed to conform to the body, distributing support forces across a large surface area to prevent slipping and discomfort. Adjustments for chest straps, shoulder straps, and arm cuffs ensure a tailored fit for various body types.
Safety features protect the user during operation, including force limits to prevent overpowering and emergency stop mechanisms. The design minimizes inhibition of the arm and torso’s natural range of motion, allowing for comfortable all-day wear.
Proper training and an adaptation period are needed for users to become proficient. This period allows individuals to familiarize themselves with the exoskeleton’s features, adjust support levels, and understand how it interacts with their movements. Managing expectations about integration into daily work routines, including potential minor fatigue in unaccustomed muscles, contributes to a positive user experience.