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Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a stable locomotion corresponding to SLIP model. Simulations are done to obtain a repeatable hopping for a three-link underactuated biped model. Results show that periodic hopping gaits can be stabilized, and the presented control strategy provides feasible gait trajectories for stance and swing phases.

For optimal vehicle yaw stability control system development, inclusion of driver dynamics seems necessary. In this paper, a novel design approach is proposed for developing optimal solutions to vehicle stability control problems in the presence of the driver-in-the-loop steering models. The design concept is inspired by a Nash strategy for exactly known systems with more than two players. In the presented method, driver, controlling the steering wheel, and vehicle stability control unit, applying braking torques on the wheels, are defined as two dynamic players in a 2-player differential LQ game, and as a result, a novel control algorithm is developed. The results from a numerical simulation of a single lane change maneuver show the effectiveness of this controller over the common LQR control approach.

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