Running mechanics in 2D

Spring-loaded inverted pendulum (SLIP): the body is a point mass bouncing on a spring leg. Grab the runner and drag it up, then let go for a drop test. Toggle Spring to see the underlying model and Strobe for a stride ghost trail.

Runner

Target speed

Apex height (x leg length)

Leg stiffness k

Leg length

Body mass

Gravity

Auto-balance controller

Manual touchdown angle

Presets

Live readouts

Vertical force and COM height

Ground force / body weightCOM height

Model: m x'' = k(L0 - L) along the leg during stance, ballistic flight otherwise (Blickhan 1989; McMahon and Cheng 1990; Geyer et al. 2006).