selfright

Selfright, or self-righting, refers to the ability of a system to return to an upright or stable orientation after being displaced. It is studied in biology, robotics, and related fields as a design principle that can improve reliability and mobility in uncertain environments.

In biology, self-righting describes adaptive reflexes or morphological features that help an organism regain an upright posture after inversion. Sea turtles, for example, perform a righting reflex when flipped onto their backs, using their limbs to push against the substrate or water. Other species may use rapid leg movements, body elongation, or curling actions to reorient themselves.

In engineering, self-righting is implemented through passive or active mechanisms. Passive self-righting relies on symmetry, buoyancy, or elastic structures that naturally reorient under gravity. Active self-righting uses sensors such as accelerometers or gyroscopes and actuators to move internal masses or the body to restore upright orientation, typically guided by a control system. Applications include search-and-rescue robots, unmanned underwater vehicles, and rolling or spherical robots designed to recover after a tumble.

Design trade-offs include energy consumption, mechanical complexity, control reliability, and effectiveness across varied terrains or fluids. Self-righting can improve robustness when continuous monitoring or remote control is impractical, but it may introduce weight, cost, or new failure modes.

See also: attitude control, self-stabilization, robotics, morphology, control systems.