Human like trajectory generation for a biped robot with a four-bar linkage for the knees

Abstract

International audienceThe design of a knee joint is a key issue in robotics to improve the locomotion and the performances of the bipedal robots. We study a design for the knee joints of a planar bipedal robot, based on a four-bar linkage. We design walking reference trajectories composed of double support phases, single support phases and impacts. The single support phases are divided in two sub-phases. During the first sub-phase the stance foot has a flat contact with the ground. During the second sub-phase the stance foot rotates on its toes. In the double support phase, both stance feet rotate. This phase is ended by an impact on the ground of the toe of the forward foot, the rear foot taking off. The single support phase is ended by an impact of the heel of the swing foot, the other foot keeping contact with the ground through its toes. A parametric optimization problem is presented for the determination of the parameters corresponding to the optimal cyclic walking gaits. In the optimization process this novel bipedal robot is successively, overactuated (double support with rotation of both stance feet), fully actuated (single support sub-phase with a flat foot contact), and underactuated (single support sub-phase with a rotation of the stance foot). A comparison of the performances with respect to a sthenic criterion is proposed between a biped equipped with four-bar knees and the other with revolute joints. Our numerical results show that the performances with a four-bar linkage are badder for the smaller velocities and better for the higher velocities. These numerical results allow us to think that the four-bar linkage could be a good technological way to increase the speed of the future bipedal robots

Kinematic Modeling and Simulation of Eleven-Links Biped Robot With Arms

“…4. The ankle trajectory and hip trajectory are known and therefore, the related parameters of the inverse kinematics are calculated as (5), (6), (7) and (8).…”

“…Aoustin and Hamon [7] worked on a four-bar linkage biped robot. They simulated the dynamic of a biped robot with four-bar linkage knees.…”

Diseño cinemático y construcción de un robot humanoide con movimientos básicos de caminado

“…En trabajos de investigación en los que se menciona la trayectoria que siguen las piernas de un humano al caminar [26] [27][28] llegan a la conclusión de que este proceso, aunque a simple vista parece sencillo, presenta un grado de dificultad a considerar ya que para poder ser reproducido de forma artificial, involucra movimientos de diversas partes del cuerpo como son: cadera, brazos, cabeza, tronco, etc. y por lo tanto no solo depende de las piernas [26]. Además, es un movimiento que no se puede representar en un solo plano, puesto que es tridimensional [29].…”

A novel gait-based synthesis procedure for the design of 4-bar exoskeleton with natural trajectories

“…The 4-bar linkage allows the combination of rotation and translation motion of the knee joint in sagittal plane [17] . Also, it has been used for the knee joint of bipedal robots [17] , [18] , [19] , [20] and prosthetic knee joints [21] ; therefore, to imitate the complex function of the knee joint for creating orthotic and rehabilitation devices, a 4-bar mechanism can be used.

Figure 1 Contact points generated while rolling and gliding motion, when femur moves relative to tibia.

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