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...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.展开更多
Compliant translational joints （CTJs） have been extensively used in precision engineering and microelectromechanical systems （MEMS）. There is an increasing need for designing higher-performance CTJs. This paper de...Compliant translational joints （CTJs） have been extensively used in precision engineering and microelectromechanical systems （MEMS）. There is an increasing need for designing higher-performance CTJs. This paper deals with the conceptual design of CTJs via three approaches： parallelogram based method, straight- line motion mechanism based method and combination based method. Typical emerging CTJ designs are reviewed by explaining their design principles and qualitatively analyzing their characteristics. New CTJs are proposed using three approaches, including an asymmetric double parallelogram mechanism with slaving mechanism, several compact and symmetric double parallelogram mechanisms with slaving mechanisms and a general CTJ using the center drift compensation and a CTJ using Roberts linkage and several combination designs. This paper provides an overview of the current advances/progresses of CTJ designs and lays the foundation for further optimization, quantitative analysis and characteristic comparisons.展开更多
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 ...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.展开更多
Micromechanics aims mainly at establishing the quantitative relation between the macroscopic mechanical behavior and the microstructure of heterogeneous materials.
基金Acknowledgment Matej Hoffmann was supported by the Swiss National Science Foundation project ＂From locomotion to cognition＂ （Grant No. 200020-122279/1）. Jakub Simanek was supported by the Grant Agency of the CTU in Prague （Grant No. SGS 15/163/OHK3/2T/13）. Matej Hoffmann would like to thank Roll Pfeifer for continuous support of this project and to the collaborators that contributed to the investigations that laid the foundations for this work, in particular Fumiya Iida, Michal Reinstein, Nico Schmidt, and students Stefan Hutter, Richard Meuris, Nicolas Ruegg, Urs Fassler, and Mathias Weyland. We would also like to thank Koh Hosoda for the idea that passive joints may increase the overall ground contact duration of individual legs and Nadja Schilling for a discussion of the ＂template＂ of leg morphology in mammalian running. Finally, we are indebted to Michal Reinstein and Kenichi Narioka for valuable comments on the manuscript.
文摘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.
文摘Compliant translational joints （CTJs） have been extensively used in precision engineering and microelectromechanical systems （MEMS）. There is an increasing need for designing higher-performance CTJs. This paper deals with the conceptual design of CTJs via three approaches： parallelogram based method, straight- line motion mechanism based method and combination based method. Typical emerging CTJ designs are reviewed by explaining their design principles and qualitatively analyzing their characteristics. New CTJs are proposed using three approaches, including an asymmetric double parallelogram mechanism with slaving mechanism, several compact and symmetric double parallelogram mechanisms with slaving mechanisms and a general CTJ using the center drift compensation and a CTJ using Roberts linkage and several combination designs. This paper provides an overview of the current advances/progresses of CTJ designs and lays the foundation for further optimization, quantitative analysis and characteristic comparisons.
基金supported by the National Natural Science Foundation of China (61005082, 61020106005)Doctoral Fund of Ministry of Education of China (20100001120005)+1 种基金PKU-Biomedical Engineering Join Seed Grant 2012the 985 Project of PekingUniversity (3J0865600)
文摘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.
文摘Micromechanics aims mainly at establishing the quantitative relation between the macroscopic mechanical behavior and the microstructure of heterogeneous materials.
