What Are Assistive Robots?

Assistive robots are robotic systems built to help people with physical, cognitive, or sensory impairment carry out tasks they cannot complete unaided, or to restore motor function lost to injury or disease. The subset aimed at recovery of movement is usually called rehabilitation robotics, and the machines themselves rehabilitation robots. Assistive robots sit where medical robotics, service robotics, and assistive technology meet, and what separates them from industrial manipulators is the requirement that they work in sustained physical contact or close proximity with a person. Their design draws on biomechanics, control theory, human factors engineering, and clinical rehabilitation science.

The field took shape in the late 1980s and 1990s, when researchers began building end-effector devices that could guide a patient's limb through repeated therapeutic movements. Two machines set the pattern: the MIT-MANUS planar arm robot for upper-limb stroke therapy, and treadmill-based gait trainers such as the Lokomat. Both rest on the same clinical premise, that high-repetition, task-specific practice drives neuroplastic reorganization, and that a machine can deliver far more repetitions per session than a therapist working by hand.

Therapy and Rehabilitation Robots

Therapy robots move, resist, or perturb a limb according to a control law tuned to the patient's residual ability. End-effector designs grip the hand or foot and move a single distal point; exoskeletal designs align joint axes with the user's own so that each anatomical degree of freedom can be controlled independently. Most clinical systems use some form of assist-as-needed control, in which the robot supplies only the torque the patient fails to generate, so that voluntary effort is preserved rather than replaced. A systematic review of robotics in physical rehabilitation found the strongest evidence for upper-limb devices in post-stroke care, with gains in motor scores that generally match conventional therapy at equal dose while requiring less therapist time per repetition.

Wearable Exoskeletons and Powered Orthoses

Powered exoskeletons are worn rather than sat in, which shifts the engineering problem from workspace design to weight, actuation efficiency, and intent detection. Actuators at the hip, knee, or ankle deliver torque in phase with the wearer's gait cycle, timed from inertial sensors, joint encoders, ground reaction force, or surface electromyography. Commercial lower-limb systems including Ekso, ReWalk, and Indego have received regulatory clearance for supervised overground training and, in some cases, personal use. A review of lower extremity assistive robotic exoskeletons in rehabilitation therapy traces the split between stationary gait trainers and untethered ambulatory devices, while work on robotics in lower-limb rehabilitation after stroke covers how control strategies are matched to stage of recovery.

Socially Assistive and Service Robots

Not every assistive robot applies force. Socially assistive robots support users through coaching, reminding, monitoring, and companionship, and their effect depends on interaction design rather than actuator power. Typical roles include prompting adherence to a home exercise program, guiding cognitive training for people with dementia, and supporting structured social skills practice in autism intervention. Feeding robots, robotic wheelchairs, and mounted manipulator arms occupy a middle ground, providing manipulation for users with limited hand function. A survey of assistive technologies for people with Parkinson's disease illustrates how sensing, actuation, and interface choices vary with the specific impairment being addressed.

Safety governs all of these categories. Because contact with the user is intentional, force and velocity limits, mechanical compliance, backdrivable transmissions, and redundant emergency stops are treated as functional requirements rather than afterthoughts. ISO 13482 sets out safety requirements for personal care robots, covering physical assistant devices, mobile servant robots, and person carriers.

Applications

Assistive robots have applications in a range of fields, including:

• Post-stroke upper-limb and gait rehabilitation in clinical and home settings
• Mobility support for spinal cord injury and other paralysis
• Elder care, including fall prevention, monitoring, and daily activity support
• Pediatric therapy and autism intervention
• Occupational injury prevention through wearable load-bearing exoskeletons
• Prosthetics and orthotics with powered joints and intent-driven control