The effect of leg impedance on stability and efficiency in quadrupedal trotting

Bosworth, William R.; Kim, Sangbae; Hogan, Neville

doi:10.1109/iros.2014.6943258

Cited by 9 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…the end-effector) to be specified by reg-ulating the dynamic relationship between forces and positions (mechanical impedance). Despite impedance is of primary importance to achieve dynamically stable robot locomotion, only recently an exhaustive research has been carried out, on the MIT Cheetah robot, to find which impedance parameters are suitable for locomotion [11]. However, an analysis that investigates if these parameters are realizable is still missing.…”

Section: Introductionmentioning

confidence: 99%

Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Focchi

Medrano-Cerda

Boaventura

et al. 2016

Control Theory Technol.

View full text Add to dashboard Cite

Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g., a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.

show abstract

Section: Introductionmentioning

confidence: 99%

Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Focchi

Medrano-Cerda

Boaventura

et al. 2016

Control Theory Technol.

View full text Add to dashboard Cite

show abstract

“…For example, Rummel et al (2010) investigated stability and robustness of walking mechanism as a criteria in selecting control parameters: stiffness, angle of attack and energy. Bosworth et al (2014) observed the effect of leg impedance on stability and energy efficiency. A similar simulation study will provide useful insight.…”

Section: Discussionmentioning

confidence: 99%

Implementation of trot-to-gallop transition and subsequent gallop on the MIT Cheetah I

Hyun

Lee

Park

et al. 2016

The International Journal of Robotics Research

Self Cite

View full text Add to dashboard Cite

This paper presents a demonstration of the trot-to-gallop transition and subsequent stable gallop in a robotic quadruped. The MIT Cheetah I, a planar quadruped platform for high-speed running, achieves these tasks with a speed of 3.2 m/s (Froude number of 2.1) on a treadmill. The controller benefits from clues from biological findings and it incorporates (1) a gait pattern modulation that imposes predefined gait patterns with a proprioceptive touchdown feedback, (2) tunable equilibrium-point foot-end trajectories for four limbs that intentionally modulate ground reaction forces, and (3) programmable leg compliance that provides instantaneous reflexes to leg–ground interaction. An inertial measurement unit sensor is integrated with the controller in order to regulate leg angles of attack at touchdown. We reduce the dimension of the control parameters which describe temporal/spatial characteristics of quadruped locomotion, and the values are tuned via dynamic simulation and then experiment. Given a pre-defined virtual leg compliance and a desired angle of attack of legs, the equilibrium-point foot-end trajectories and phase relationships between four legs for stable trot and gallop gaits are found independently. We propose a simple throw-and-catch gait transition strategy which connects two stable limit cycles, the trot and the gallop, by linearly varying control parameters during the transition period. Successful gait transition is achieved in both simulation and experiment. Comprehensive analysis on the characteristics of the MIT Cheetah I experimental trot-to-gallop transition is provided. The phase portraits imply that stable limit cycles are achieved with the proposed controller in both trot and gallop, which enables the trot-to-gallop gait transition at high speed.

show abstract

“…A good solution to deal with the impact is making the end-effector of robots work like a spring-damper [40], while the stiffness and damping should be variable with respect to time, terrains and tasks [41], [42]. Unfortunately, how to choose the suitable impedance parameters to keep the system stable is seldom discussed [25], [43].…”

mentioning

confidence: 99%

Compliance Control and Analysis for Equivalent Hydraulic Legs

et al. 2020

View full text Add to dashboard Cite

In this article, the compliant behavior of an equivalent hydraulic leg is achieved by combining active compliance control of hydraulic cylinder with a passive spring at its end effector. Firstly, a positionbased active compliance control is proposed based on impedance control to reduce the contact impact. Secondly, the stability of proposed compliance controller and the range of impedances (Z-width) of compliance control are analyzed, and the design procedure of proposed compliance controller is given out. Finally, experimental results show that the contact impacts could be well handled by the proposed control method. This research provides an insight for the compliance control of hydraulic legged robots.

show abstract

The effect of leg impedance on stability and efficiency in quadrupedal trotting

Cited by 9 publications

References 17 publications

Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Implementation of trot-to-gallop transition and subsequent gallop on the MIT Cheetah I

Compliance Control and Analysis for Equivalent Hydraulic Legs

Contact Info

Product

Resources

About