It is provided a system for improving locomotion of a human user, by changing an inclination or height of a stance surface of a device for donning on a leg during walking. The system includes a device, a sensor and a microprocessor. The device includes a platform which securely receives the shoe or foot of the user, a sole and mechanisms between the platform and the sole. Each mechanism has a motor and a thrusting element which changes the height of the platform relative to the sole. The sensor is associated with the lower limb, it senses the locomotion of the user and issues a corresponding data signal to the microprocessor. The microprocessor processes the locomotion information, determines the locomotion phase, and controls the mechanisms to effect changing of the inclination and/or the height of the stance surface during a swing phase. Also, the microprocessor introduces random changes thereof.