Uniped

Uniped is a term used in biomechanics and robotics to denote a person or device that uses a single leg for locomotion. The word combines un- meaning one and pes (foot), reflecting the primary feature of single-leg movement. In biological contexts, true unipedal organisms are extremely rare. Most documented cases involve individuals with a single supporting limb due to congenital limb deficiency or traumatic amputation. Locomotion under these conditions must address substantial balance challenges, asymmetric gait, and increased energy expenditure, often requiring assistive devices or rehabilitation.

In robotics and prosthetics, uniped locomotion is an active area of study. Researchers examine single-leg stability, gait generation, foot placement, and transitions between phases. Dynamic models such as the linear inverted pendulum model are used to analyze center of mass trajectories and balance. Control strategies typically combine hip and knee actuation with ankle torque and sensory feedback to adapt to uneven terrain. Actuators range from electromechanical joints to hydraulic systems, and perception systems provide proprioceptive and contact information.

Applications include rehabilitation devices for individuals with leg loss, as well as laboratory prototypes of legged robots designed to operate on a single supporting leg for efficiency or robustness in certain tasks. Compared with bipedal designs, uniped systems face greater risk of tipping, require precise control, and may sacrifice speed and stability for simplicity and compactness.

See also: bipedalism, monopedal locomotion, gait analysis.