Design principles for highly efficient quadrupeds and implementation on the MIT Cheetah robot

Seok, Sangok; Wang, Albert; Chuah, Meng Yee; Otten, David; Lang, Jeffrey H.; Kim, Sangbae

doi:10.1109/icra.2013.6631038

Cited by 372 publications

(209 citation statements)

References 15 publications

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“…Most leggedrobots however use rotary motors driving articulated legs with rotary joints (Boaventura et al, 2012;Hutter et al, 2012;M. Raibert et al, 2008;Seok et al, 2013), in which case hip-torque becomes important to generating leg-thrust. In biology also, several studies indicate that hip-torque plays a key role in generating leg-thrust (Tan and Wilson, 2011).…”

Section: Hypothesismentioning

confidence: 99%

On designing an active tail for legged robots: simplifying control via decoupling of control objectives

Heim

Ajallooeian

Eckert

et al. 2016

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Abstract-This work explores the possible roles of active tails for steady-state legged-locomotion. A series of simple models are proposed which capture the dynamics of an idealized running system with an active tail. The models suggest that the control objectives of injecting energy into the system and stabilizing body-pitch can be effectively decoupled via proper tail design: a long, light tail. Thus the overall control problem can be simplified, using the tail exclusively to stabilize body-pitch: this effectively relaxes the constraints on the leg-actuators, allowing them to be recruited specifically for adding energy into the system. We show in simulation that models with long-light tails are better able to reject perturbations to body-pitch than short-heavy tails with the same moment of inertia. Further, we present the results of a one degree-of-freedom tail mounted on the open-loop controlled quadruped robot Cheetah-Cub. Our results show that an active tail can greatly improve both forward velocity and reduce body-pitch per stride, while adding minimal complexity. Further, the results validate the long-light tail design: shorter, heavier tails are much more sensitive to configuration and control parameter changes than longer and lighter tails with the same moment of inertia.

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Section: Hypothesismentioning

confidence: 99%

On designing an active tail for legged robots: simplifying control via decoupling of control objectives

Heim

Ajallooeian

Eckert

et al. 2016

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“…Another electrically actuated robot with purely impedance-controlled legs is the MIT cheetah robot. Seok et al [35,34] presented a quadruped robot with joint torque control, implemented with electric motors with low gear ratio (5.8:1) and current control. No springs or torque sensing elements are needed in this approach (except an elastic spine for energy storage).…”

Section: Legged Robots With Active Impedancementioning

confidence: 99%

Is Active Impedance the Key to a Breakthrough for Legged Robots?

Semini

Barasuol

Boaventura

et al. 2016

Springer Tracts in Advanced Robotics

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This work addresses the question whether active impedance control is key to a breakthrough for legged robots. In this paper, we will talk about controlling the mechanical impedance of joints and legs with a focus on stiffness and damping control. In contrast to passive elements like springs, active impedance is achieved by torque-controlled joints allowing real-time adjustment of stiffness and damping. We argue that legged robots require a high degree of versatility and flexibility to execute a wide range of assistive tasks to be truly useful to humans and thus to lead to a breakthrough. Adjustable stiffness and damping in realtime is a fundamental building block towards versatility. Experiments with our 80 kg hydraulic quadruped robot HyQ demonstrate that active impedance alone (thus no springs in the structure) can successfully emulate passively compliant elements during highly-dynamic locomotion tasks (running and hopping); and, that no springs are needed to protect the actuation system. Here we present results of a flying trot, also referred to as running trot. To the authors' best knowledge this is the first time a flying trot was successfully implemented on a robot without passive elements such as springs. A critical discussion on the pros and cons of active impedance concludes the paper.

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“…The regenerative power can be converted to an available power source by the regenerative system. 9 However, this technology is very expensive to construct; therefore, the regenerative power is usually dissipated as heat by the internal dump resistor. This causes energy loss.…”

Section: Regenerative Power Dissipation Reductionmentioning

confidence: 99%

Energy-saving method of parallel mechanism by redundant actuation

Lee

Sul

Kim

2015

Int. J. of Precis. Eng. and Manuf.-Green Tech.

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This paper presents a novel energy-saving method of a robotic system utilizing parallel mechanism by redundant actuation. The redundantly actuated system can distribute arbitrary actuating torques in a certain combination. By using this feature, the regenerative power dissipation and electric power loss are reduced. Moreover, the redundant actuation can reduce the peak torque of actuating joints. This feature reduces the friction loss because we can use a smaller gear reducer. A parallel manipulator with two degrees of freedom is simulated as a case study. The energy consumption of the robotic system is modeled by analyzing the type of energy consumption in actuation systems. An optimization process is proposed to maximize the energy-saving effect. The results show that 26.1% of electric energy can be saved by redundant actuation.

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Design principles for highly efficient quadrupeds and implementation on the MIT Cheetah robot

Cited by 372 publications

References 15 publications

On designing an active tail for legged robots: simplifying control via decoupling of control objectives

On designing an active tail for legged robots: simplifying control via decoupling of control objectives

Is Active Impedance the Key to a Breakthrough for Legged Robots?

Energy-saving method of parallel mechanism by redundant actuation

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