The fluid pressures in compressible fluid pressure actuators (6a, 6b) articulately driven by an antagonizing motion are controlled by a main fluid pressure control means (23). When a sudden braking occurs at the time of collision, the actuators running at high speeds are pressurized or depressurized for sudden acceleration or deceleration by proximate fluid pressure high-speed control means (9a, 9b, 20a, 20b) located near the actuators.