Effects of Stance Width on Control Gain in Standing Balance

Standing in a wide stance during a lateral perturbation is considered to be easier than standing in a narrow stance, but the basis for this ease of stance is not understood. To study the effects of increased stance width in balance control, we created a standing model of a cat with variable stance width and subjected it to lateral displacement perturbations. We studied balance control while varying postural orientation and control parameters that are not accessible in a biological cat. We determined that delayed feedback in the postural controller necessitates the reduction of active feedback gain as stance width increases from narrow to wide stance. By establishing the change in control requirements in a system that resembles a biological configuration, we can predict that similar control changes may occur in biological systems.