Modeling and analysis of passive dynamic bipedal walking with segmented feet and compliant joints

Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of fiat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes foot rotations around the toe joint and around the toe tip, which shows a great resemblance to human normal walking. This paper investigates the effects of the segmented foot structure on bipedal walking in simulations. The model achieves satisfactory walking results on even or uneven slopes.

The Merits of Passive Compliant Joints in Legged Locomotion： Fast Learning, Superior Energy Efficiency and Versatile Sensing in a Quadruped Robot

A quadruped robot with four actuated hip joints and four passive highly compliant knee joints is used to demonstrate the potential of underactuation from two standpoints： learning locomotion and perception. First, we show that： （i） forward locomotion on flat ground can be learned rapidly （minutes of optimization time）; （ii） a simulation study reveals that a passive knee configuration leads to faster, more stable, and more efficient locomotion than a variant of the robot with active knees; （iii） the robot is capable of learning turning gaits as well. The merits of underactuation （reduced controller complexity, weight, and energy consumption） are thus preserved without compromising the versatility of behavior. Direct optimization on the reduced space of active joints leads to effective learning of model-free controllers. Second, we find passive compliant joints with po- tentiometers to effectively complement inertial sensors in a velocity estimation task and to outperform inertial and pressure sensors in a terrain detection task. Encoders on passive compliant joints thus constitute a cheap and compact but powerful sensing device that gauges joint position and force/torque, and -- if mounted more distally than the last actuated joints in a legged robot -- it delivers valuable information about the interaction of the robot with the ground.

Design,Fabrication and Experiments of an Anthropomorphic Finger with Combined Compliant Joints

Fingers are the basic components of anthropomorphic hands.At present,most anthropomorphic fingers utilize rigid joints,which have obvious fabrication and assembly complexities as well as limited flexibility and adaptability.Thus,some anthropomorphic fingers were attempted to utilize compliant joints learned from bioinspiration,but they have a limited self-resetting ability and lateral deformation resistance,as well as occupying a large space and having a non-anthropomorphic appearance.In this paper,nine compliant joints for anthropomorphic fingers were analyzed using Finite Element Analysis(FEA),based on which two combined compliant joints were proposed,and the optimal one was obtained through FEA and experiments.An anthropomorphic finger that embeds parts of the compliant joint into the adjacent phalanxes was then designed.Finally,the anthropomorphic finger was fabricated and experiments were conducted.Experimental results show that the anthropomorphic finger with the proposed combined compliant joints has a better self-resetting ability and lateral deformation resistance while ensuring a large range of motion similar to that of the human finger,and the required actuating force is reasonable.Furthermore,the embedded joint structure can reduce the occupied space of the joint so as to improve the anthropomorphic appearance of the finger,and enhance its lateral deformation resistance.

Preface

Micromechanics aims mainly at establishing the quantitative relation between the macroscopic mechanical behavior and the microstructure of heterogeneous materials.

Driving Torque Reduction in Linkage Mechanisms Using Joint Compliance for Robot Head

The conventional linkage mechanisms with compliant joint have been widely studied and implemented for increasing the adaptability of the mechanism to external contacts. However, the analysis of how compliant joints in linkage mechanism can reduce the energy consumption isn＇t still studied deeply. In a mobile service robot head, the actions of blinking the eyes and moving the eyeballs are realized by the planar linkage mechanism respectively. Therefore, minimizing the driving torques through motion trajectories for the linkage mechanism, which will be beneficial to extend the working time for mobile service robots. The dynamic modeling of the linkage mechanism with springs-loaded compliant joint is established. An optimization procedure for obtaining the optimal parameters of springs is proposed for minimizing the max value of driving torques within a range of desired operating conditions. The Simulations prove that the linkage mechanism with compliant joints can effectively reduce the driving torques, and reduce the energy consumption consequently. The framework can also be applied in other similar applications to reduce the driving torque and save energy. Compared with previous efforts, this is the first attempt that the linkage mechanism with complaint joint is applied in the robot head for reducing the driving torque.