Trunk motions are typically used to stabilize the locomotion of biped robots, which can be very large in some leg trajectories. This paper proposes a method to reduce the motion range of the trunk by generating a desired trajectory of the ZMP. The trajectory is determined by a fuzzy logic based upon the leg trajectories that are arbitrary selected. The resulting ZMP trajectory is similar to hum...

Swing-leg retraction, the backward rotation of the swing leg just prior to ground contact, is observed in human locomotion. While several advantages of swingleg retraction, like gait stability and perturbation rejection, are shown by conceptual models, there is currently very little experimental data on swing-leg retraction in human motion. In this paper, kinematic data for twenty-eight subject...

Locomotion can be described as a subsequent series of stance and flight phases. In both phases the leg properties can be adapted. Here we consider spring-mass running with a linear adaptation of two leg parameters, leg angle and leg stiffness, during swing phase. The region of stability is characterized by the basin of attraction with sufficient reduction of a given perturbation within one step...

Legged locomotion requires the determination of a number of parameters such as stride period, stride length, order of leg movements, leg trajectory, etc. How are these parameters determined? It has been reported that the locomotor patterns of many legged animals exhibit common characteristics, which suggests that there exists a basic strategy for legged locomotion. In this study we derive an eq...

The walking and surface film locomotion of a terrestrial spider, Lycosa rabida Walckenaer, and a semi-aquatic spider, Dolomedes triton (Walckenaer), are compared. Stepping patterns during locomotion on a solid substrate resemble an alternating tetrapod in both species. L. rabida retains elements of the terrestrial gait when moving on water: propulsive thrusts are concentrated at the tarsi and i...

We understand little about how animals adjust locomotor behaviour to negotiate uneven terrain. The mechanical demands and constraints of such behaviours likely differ from uniform terrain locomotion. Here we investigated how common pheasants negotiate visible obstacles with heights from 10 to 50% of leg length. Our goal was to determine the neuro-mechanical strategies used to achieve robust sta...

This paper investigates the possible sources of stochasticity and their relative role in metastability of legged locomotion in its simplest form. Passive locomotion of a rimless wheel suggests that stochasticity is an intrinsic–and thus unavoidable– property of legged locomotion. Numerical test results of several hypotheses have been presented on the source of stochasticity of walking: the stoc...

In this paper, we propose a scheme for fault detection and tolerance of the hexapod robot locomotion on even terrain. The fault stability margin is defined to represent potential stability which a gait can have in case a sudden fault event occurs to one leg. Based on this, the fault-tolerant quadruped periodic gaits of the hexapod walking over perfectly even terrain are derived. It is demonstra...

This thesis presents a hierarchical control algorithm for quadrupedal locomotion. We address three challenges in developing a controller for high-speed running: locomotion stability, control of ground reaction force, and coordination of four limbs. To tackle these challenges, the proposed algorithm employs three strategies. Leg impedance control provides programmable virtual compliance of each ...

Most studies addressing local feedback mechanisms are focused on posture and walking but only little is known about their role in fast locomotion. Some experimental studies on humans indicate a decrease in the activity of sensory signals with increasing speed (Collins et al. 1998, Simonsen and Dyhre-Poulsen 1999). It seems to be generally accepted that in fast movements the dynamics of the musc...