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107
On the dynamics of bounding and extensions towards the half-bound and the gallop gaits
- In Proceedings of the 2nd International Symposium on Adaptive Motion of Animals and Machines (AMAM
, 2003
"... Abstract. This paper examines how simple control laws stabilize complex run-ning behaviors such as bounding. First, we discuss the unexpectedly different local and global forward speed versus touchdown angle relationships in the self stabilized SLIP. Then we show that, even for a more complex, energ ..."
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Cited by 20 (2 self)
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Abstract. This paper examines how simple control laws stabilize complex run-ning behaviors such as bounding. First, we discuss the unexpectedly different local and global forward speed versus touchdown angle relationships in the self stabilized SLIP. Then we show that, even for a more complex, energy conserving, unactuated quadrupedal model, many bounding motions exist, which can be locally open loop stable! The success of simple bounding controllers motivated the use of similar con-trol laws for asymmetric gaits resulting in the first experimental implementations of the half-bound and the rotary gallop gaits on Scout II. 1
On the stable passive dynamics of quadrupedal running
- International Conference on Robotics & Automation
, 2003
"... In this thesis, the dynamics of quadrupedal running via the bounding gait is studied. To analyse the properties of the passive dynamics of Scout II, a model consisting of a body and two massless spring-loaded prismatic legs is introduced. A return map is derived to study the existence of periodic sy ..."
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Cited by 18 (7 self)
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In this thesis, the dynamics of quadrupedal running via the bounding gait is studied. To analyse the properties of the passive dynamics of Scout II, a model consisting of a body and two massless spring-loaded prismatic legs is introduced. A return map is derived to study the existence of periodic system motions. Numerical studies of the return map show that passive generation of cyclic motion is possible. Most strikingly, local stability analysis of the return map shows that the dynamics of the open loop passive system alone can confer stability of the motion. Stability improves at higher speeds, a fact which is in agreement with recent results from Biomechanics showing that the dynamics of the body become dominant in determining stability when animals run at high speeds. Furthermore, pronking is found to be more unstable than bounding, which explains why Scout II shows a “preference ” for the bounding gait. These results can be used in developing a general control methodology for legged robots, resulting from the synthesis of feed-forward and feedback models that take advantage of the
Mechanical aspects of legged locomotion control
, 2004
"... We review the mechanical components of an approach to motion science that enlists recent progress in neurophysiology, biomechanics, control systems engineering, and non-linear dynamical systems to explore the integration of muscular, skeletal, and neural mechanics that creates effective locomotor be ..."
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Cited by 16 (2 self)
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We review the mechanical components of an approach to motion science that enlists recent progress in neurophysiology, biomechanics, control systems engineering, and non-linear dynamical systems to explore the integration of muscular, skeletal, and neural mechanics that creates effective locomotor behavior. We use rapid arthropod terrestrial locomotion as the model system because of the wealth of experimental data available. With this foundation, we list a set of hypotheses for the control of movement, outline their mathematical underpinning and show how they have inspired the design of the hexapedal robot, RHex.
Self-stabilization and behavioral diversity of embodied adaptive locomotion
- Lecture Notes in Artificial Intelligence
, 2004
"... Abstract. Locomotion is of fundamental importance in understanding adaptive behavior. In this paper we present two case studies of robot locomotion that demonstrate how higher level of behavioral diversity can be achieved while observing the principle of cheap design. More precisely, it is shown tha ..."
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Cited by 15 (3 self)
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Abstract. Locomotion is of fundamental importance in understanding adaptive behavior. In this paper we present two case studies of robot locomotion that demonstrate how higher level of behavioral diversity can be achieved while observing the principle of cheap design. More precisely, it is shown that, by exploiting the dynamics of the system-environment interaction, very simple controllers can be designed which is essential to achieve rapid locomotion. Special consideration must be given to the choice of body materials. We conclude with some speculation about the importance of locomotion for understanding cognition. 1
Towards a factored analysis of legged locomotion models
- University of Michigan
, 2002
"... In this paper, we report on a new stability analysis for hybrid legged locomotion systems based on factoriza-tion of return maps. We apply this analysis to a fam-ily of models of the Spring Loaded Inverted Pendulum (SLIP) with di®erent leg recirculation strategies. We obtain a necessary condition fo ..."
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Cited by 14 (4 self)
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In this paper, we report on a new stability analysis for hybrid legged locomotion systems based on factoriza-tion of return maps. We apply this analysis to a fam-ily of models of the Spring Loaded Inverted Pendulum (SLIP) with di®erent leg recirculation strategies. We obtain a necessary condition for the asymptotic sta-bility of those models, which is formulated as an ex-act algebraic expression despite the non-integrability of the SLIP dynamics. We outline the application of this analysis to other models of legged locomotion and its importance for the stability of legged robots and an-imals. 1
Bipedal walking and running with compliant legs
- in Proc. IEEE Int. Conf. Robot. Autom
, 2007
"... Abstract — Passive dynamics plays an important role in legged locomotion of the biological systems. The use of passive dy-namics provides a number of advantages in legged locomotion such as energy efficiency, self-stabilization against disturbances, and generating gait patterns and behavioral divers ..."
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Cited by 13 (3 self)
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Abstract — Passive dynamics plays an important role in legged locomotion of the biological systems. The use of passive dy-namics provides a number of advantages in legged locomotion such as energy efficiency, self-stabilization against disturbances, and generating gait patterns and behavioral diversity. Inspired from the theoretical and experimental studies in biomechanics, this paper presents a novel bipedal locomotion model for walking and running behavior which uses compliant legs. This model consists of three-segment legs, two servomotors, and four passive joints that are constrained by eight tension springs. The self-organization of two gait patterns (walking and running) is demonstrated in simulation and in a real-world robot. The analysis of joint kinematics and ground reaction force explains how a minimalistic control architecture can exploit the particular leg design for generating different gait patterns. Moreover, it is shown how the proposed model can be extended for controlling locomotion velocity and gait patterns with the simplest control architecture. I.
Performance analysis and feedback control of ATRIAS, a 3D bipedal robot,”
- ASME J. Dyn. Sys. Meas. Control,
, 2013
"... This paper develops feedback controllers for walking in 3D, on level ground, with energy efficiency as the performance objective. Assume The Robot Is A Sphere (ATRIAS) 2.1 is a new robot that has been designed for the study of 3D bipedal locomotion, with the aim of combining energy efficiency, spee ..."
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Cited by 11 (7 self)
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This paper develops feedback controllers for walking in 3D, on level ground, with energy efficiency as the performance objective. Assume The Robot Is A Sphere (ATRIAS) 2.1 is a new robot that has been designed for the study of 3D bipedal locomotion, with the aim of combining energy efficiency, speed, and robustness with respect to natural terrain variations in a single platform. The robot is highly underactuated, having 6 actuators and, in single support, 13 degrees of freedom. Its sagittal plane dynamics are designed to embody the spring loaded inverted pendulum (SLIP), which has been shown to provide a dynamic model of the body center of mass during steady running gaits of a wide diversity of terrestrial animals. A detailed dynamic model is used to optimize walking gaits with respect to the cost of mechanical transport (CMT), a dimensionless measure of energetic efficiency, for walking speeds ranging from 0.5 m=s ð Þ to 1.4 m=s ð Þ. A feedback controller is designed that stabilizes the 3D walking gaits, despite the high degree of underactuation of the robot. The 3D results are illustrated in simulation. In experiments on a planarized (2D) version of the robot, the controller yielded stable walking.
PASSIVE VARIABLE COMPLIANCE FOR DYNAMIC LEGGED Robots
, 2010
"... Recent developments in legged robotics have found that constant stiffness passive compliant legs are an effective mechanism for enabling dynamic locomotion. In spite of its success, one of the limitations of this approach is reduced adaptability. The final leg mechanism usually performs optimally fo ..."
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Cited by 10 (3 self)
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Recent developments in legged robotics have found that constant stiffness passive compliant legs are an effective mechanism for enabling dynamic locomotion. In spite of its success, one of the limitations of this approach is reduced adaptability. The final leg mechanism usually performs optimally for a small range of conditions such as the desired speed, payload, and terrain. For many situations in which a small locomotion system experiences a change in any of these conditions, it is desirable to have a tunable stiffness leg for effective gait control. To date, the mechanical complexities of designing usefully robust tunable passive compliance into legs has precluded their implementation on practical running robots. In this thesis we present an overview of tunable stiffness legs, and introduce a simple leg model that captures the spatial compliance of our tunable leg. We present experimental evidence supporting the advantages of tunable stiffness legs, and implement what we believe is the first autonomous dynamic legged robot capable of automatic leg stiffness adjustment. Finally we discuss design objectives, material considerations, and manufacturing methods that lead to robust passive
Enlarging regions of stable running with segmented legs
- In IEEE international conference on robotics and automation (ICRA
, 2008
"... Abstract — In human and animal running spring-like leg behavior is found, and similar concepts have been demonstrated by various robotic systems in the past. In general, a spring-mass model provides self-stabilizing characteristics against external perturbations originated in leg-ground interactions ..."
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Cited by 9 (1 self)
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Abstract — In human and animal running spring-like leg behavior is found, and similar concepts have been demonstrated by various robotic systems in the past. In general, a spring-mass model provides self-stabilizing characteristics against external perturbations originated in leg-ground interactions and motor control. Although most of these systems made use of linear spring-like legs. The question addressed in this paper is the influence of leg segmentation (i.e. the use of rotational joint and two limb-segments) to the self-stability of running, as it appears to be a common design principle in nature. This paper shows that, with the leg segmentation, the system is able to perform self-stable running behavior in significantly broader ranges of running speed and control parameters (e.g. control of angle of attack at touchdown, and adjustment of spring stiffness) by exploiting a nonlinear relationship between leg force and leg compression. The concept is investigated by using a two-segment leg model and a robotic platform, which demonstrate the plausibility in the real world. I.
Running and walking with compliant legs
- In: Diehl, M., Mombaur, K. (Eds.), Fast Motions in Biomechanics and Robotics: Optimization and Feedback Control
"... It has long been the dream to build robots which could walk and run with ease. To date, the stance phase of walking robots has been characterized by the use of either straight, rigid legs, as is the case of passive walkers, or by the use of articulated, kinematically-driven legs. In contrast, the de ..."
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Cited by 9 (2 self)
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It has long been the dream to build robots which could walk and run with ease. To date, the stance phase of walking robots has been characterized by the use of either straight, rigid legs, as is the case of passive walkers, or by the use of articulated, kinematically-driven legs. In contrast, the design of most hopping or running robots is based on compliant legs which exhibit quite natural behavior during locomotion. Here we ask to what extent spring-like leg behavior could be useful in unifying locomotion models for walking and running. In so doing, we com-bine biomechanical experimental and computer simulation approaches with theoretical considerations and simple legged robots. We have found that (1) walking and running result from mechanical sta-bility which corresponds to the experimentally observed gait dynamics, (2) running is a subset of stable movement patterns for high system energies, and (3) walking with knee flexion during stance can result from passive leg mechanics with elastic structures spanning the joints. 1
