Modeling, control and simulation of upward jump of a biped

This paper explores the vertical upward jumping of a planar biped. The jumping process is decomposed into the crouching phase, the thrust in the knees, the flight phase, the touchdown, and the straightening up movement of the biped. A mathematical model for this kind of jump of the biped is developed. Torques are applied in the hip and knee joints. The degree of underactuation of the mechanism is equal to one in the support phase and to three in the flight phase. The control algorithm is designed to ensure the jump of the biped. This algorithm is such that the center of mass of the mechanism is always placed on the same vertical line. The biped touches the ground in the same place where it starts from. The synthesis of the jumping process is supported by simulations which give consistent results with human data from existing biomechanical literature. Furthermore, the stick diagram of the jump derived from these simulation results seems natural for the human jumping. The problem of energy recovery is considered for the jumping of the biped by using springs in the hip and knee joints. The springs have an influence to minimize the mechanical energy consumed by the drives in the hip and knee joints. The springs in the knees help to increase the lifting of the bipedal mechanism.     

Three-Link Mechanism as a Model of a Person on a Swing

Journal of Computer and Systems Sciences International - We model movements of a person swinging on a swing. We consider a flat three-link hinged mechanism as the main mechanical model of the...     

Walking of biped with passive exoskeleton: evaluation of energy consumption

The paper aims to theoretically show the feasibility and efficiency of a passive exoskeleton for a human walking and carrying a load. The human is modeled using a planar bipedal anthropomorphic mechanism. This mechanism consists of a trunk and two identical legs; each leg consists of a thigh, shin, and foot (massless). The exoskeleton is considered also as an anthropomorphic mechanism. The shape and the degrees of freedom of the exoskeleton are identical to the biped (to human)—the topology of the exoskeleton is the same as of the biped (human). Each model of the human and exoskeleton has seven links and six joints. The hip-joint connects the trunk and two thighs of the two legs. If the biped is equipped with an exoskeleton, then the links of this exoskeleton are attached to the corresponding links of the biped and the corresponding hip, knee, and ankle joints coincide. We compare the walking gaits of a biped alone (without exoskeleton) and of a biped equipped with exoskeleton; for both cases the same load is transported. The problem is studied in the framework of a ballistic walking model. During ballistic walking of the biped with exoskeleton, the knee of the support leg is locked, but the knee of the swing leg is unlocked. The locking and unlocking can be realized in the knees of the exoskeleton by any mechanical brake devices without energy consumption. There are no actuators in the exoskeleton. Therefore, we call it a passive exoskeleton. The walking of the biped consists of alternating single- and double-support phases. In our study, the double-support phase is assumed instantaneous. At the instant of this phase, the knee of the previous swing leg is locked and the knee of the previous support leg is unlocked. Numerical results show that during the load transport the human with the exoskeleton spends less energy than human alone. For transportation of a load with mass 40 kg, the economy of the energy is approximately 28%, if the length of the step and its duration are equal to 0.5 m and 0.5 s, respectively.     

3D walking biped: optimal swing of the arms

A ballistic walking gait is designed for a 3D biped with two identical two-link legs, a torso, and two identical one-link arms. In the single support phase, the biped moves due to the existence of a momentum, produced mechanically, without applying active torques in the interlink joints. This biped is controlled with impulsive torques at the instantaneous double support to obtain a cyclic gait. The impulsive torques are applied in the seven interlink joints. Then an infinity of solutions exists to find the impulsive torques. An effort cost functional of these impulsive torques is minimized to determine a unique solution. Numerical results show that for a given time period and a given length of the walking gait step, there is an optimal swinging amplitude of the arms. For this optimal motion of the arms, the cost functional is minimum.