🏃 Walking Gait Analysis

Gait analysis is the systematic study of human walking, measuring how the legs, joints and body move through each step. Clinically it quantifies parameters such as joint angles, step length, cadence, ground reaction forces and symmetry to diagnose movement disorders and plan rehabilitation. This simulation presents a simplified, visual version of those measurements.

During the stance phase the supporting leg behaves like a rigid strut, so the body's centre of mass arcs over the planted foot like an inverted pendulum. Potential energy peaks at mid-stance and converts back to kinetic energy as the body falls forward, recovering up to about 65% of the mechanical energy passively. The natural swing period scales as T = 2π√(L/g), where L is leg length and g is gravity.

The mode buttons load presets for healthy and pathological gait: Parkinson's gives short, shuffling, variable steps; stroke produces an asymmetric pattern with stiff-knee and foot-drop on the affected side; prosthetic shows reduced knee flexion. The sliders independently set walking speed, step length and cadence, which together determine stride length, energy cost and the animation's cycle period.

It is a teaching approximation rather than a clinical-grade model. The joint-angle curves, double-hump ground reaction force and the roughly 60/40 stance-to-swing split reflect real walking patterns, and the preset values for speed, cadence and symmetry are realistic. However the joints are driven by simple sinusoids rather than solved from full musculoskeletal dynamics, so fine timing and forces are illustrative only.

The double-humped vertical force is a hallmark of normal walking. The first peak occurs just after heel strike as the body weight loads onto the limb and decelerates the downward motion of the centre of mass; the trough at mid-stance happens as the body rises over the leg; the second peak comes at push-off when the ankle propels the body forward. Loss of one peak often signals a gait abnormality.