Leg design for running and jumping dynamics

Blackman, Daniel J.; Nicholson, John; Pusey, Jason; Austin, Max P.; Young, Charles A.; Brown, Jason; Clark, Jonathan E.

doi:10.1109/robio.2017.8324814

Cited by 10 publications

(4 citation statements)

References 18 publications

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“…In the analysis of a symmetric five-bar linkage, Kenneally and Koditschek [37] measured performance according to the conversion of battery energy into body energy, the minimization of touchdown losses, and the storing/return of energy during stance. Blackman et al [38] extended their analysis, highlighting the ability of this symmetric five-bar to achieve greater speeds and stability in one configuration, but greater jump height in another. Brown et al [39] analyzed the ability of this five-bar and other linkage designs to balance workloads between motors.…”

Section: B Design Principles For Legged Robotsmentioning

confidence: 98%

Designing Dynamic Machines With Large-Scale Root Finding

Plecnik

Fearing

2020

IEEE Trans. Robot.

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Achieving high-performance dynamic behavior in a robot requires careful design of morphology. However, searching for a global optimum morphology in an intensely nonlinear design space is difficult, especially if stochastic seeding is used. In contrast to optimization, we encode design requirements into a polynomial system with a huge number of isolated roots. Each root describes an alternate robot morphology in the design space. Following this, the computation of nearly all isolated roots constitutes design space exploration. Previously, these systems were intractable, due to the heavy burden of degenerate roots. We relieve this burden by using the finite root generation (FRG) method to enable the discovery of nearly all isolated roots for a certain six-bar design problem for the first time. The FRG synthesis method enables the design of a transmission function from motor dynamics to a loaded end effector to influence the overall dynamic behavior. In an example, we formulate synthesis equations which were previously intractable, obtain 1 528 608 isolated roots (estimated 99.0%), and find 3764 physical designs. Design options are compared according to their sensitivity to joint errors.

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Section: B Design Principles For Legged Robotsmentioning

confidence: 98%

Designing Dynamic Machines With Large-Scale Root Finding

Plecnik

Fearing

2020

IEEE Trans. Robot.

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“…Each leg was controlled by two BLDC motors that actuated the legs as seen in figure 2. These low-profile outrunner motors (Quanum 5250, DYS motors) are common in recent small to mid-size legged robots [54][55][56][57][58][59]. Motor current control for the two motors were performed by a single ODrive motor controller (ODrive Robotics, Richmond, CA), which performed commutation at 10 kHz.…”

Section: Leg Design and Controlmentioning

confidence: 99%

“…Critically, proprioceptive-based methods rely on actuator and transmission systems that have low gear-ratios, low friction, and high backdrivability [52,53]. Direct-drive actuation achieves all of these qualities and is increasingly prevalent in the regime of medium-small legged robots [39,[54][55][56][57][58][59]. The lowgear ratio motors provide tight control over the forces that legs impart on the ground enabling impressive dynamic robots [60].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic compliance of robot legs improves recovery from swing-phase collisions

Chang¹,

Chang²,

Clifton³

et al. 2021

Bioinspir. Biomim.

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Uneven terrain in natural environments challenges legged locomotion by inducing instability and causing limb collisions. During the swing phase, the limb releases from the ground and arcs forward to target a secure next foothold. In natural environments leg–obstacle collisions may occur during the swing phase which can result in instability, and may require contact sensing and trajectory re-planning if a collision occurs. However, collision detection and response often requires computationally- and temporally-expensive control strategies. Inspired by low stiffness limbs that can pass past obstacles in small insects and running birds, we investigated a passive method for overcoming swing-collisions. We implemented virtual compliance control in a robot leg that allowed us to systematically vary the limb stiffness and ultimately its response to collisions with obstacles in the environment. In addition to applying a standard positional control during swing motion, we developed two virtual compliance methods: (1) an isotropic compliance for which perturbations in the x and y directions generated the same stiffness response, and (2) a vertical anisotropic compliance in which a decrease of the upward y vertical limb stiffness enabled the leg to move upwards more freely. The virtual compliance methods slightly increased variability along the limb’s planned pathway, but the anisotropic compliance control improved the successful negotiation of step obstacles by over 70% compared to isotropic compliance and positional control methods. We confirmed these findings in simulation and using a self-propelling bipedal robot walking along a linear rail over bumpy terrain. While the importance of limb compliance for stance interactions have been known, our results highlight how limb compliance in the swing-phase can enhance walking performance in naturalistic environments.

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“…The weights of the cited small-sized platforms range from 1.1 g [24] to 1.3 kg [26]. Generally, legged robots heavier than 1.3 kg combine power modulation and cyclic appendage trajectories with multiple actuators [34]- [37]. The increased number of actuators increases power output and degrees of freedom, but it also increases the weight of the platform.…”

Section: Introductionmentioning

confidence: 99%

Elastic-Actuation Mechanism for Repetitive Hopping Based on Power Modulation and Cyclic Trajectory Generation

et al. 2023

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Animal locomotion results from a combination of power modulation and cyclic appendage trajectories, but combining these two properties in small-sized robots is difficult. Here, we introduce and characterize a new elastic actuation system based on an inverted cam that is capable of generating cyclic locomotion with controlled elastic energy charge and release for small-sized robots. We designed a leg linkage and attached to the inverted cam to develop a single legged hopping platform with one actuated degree of freedom. The hopping platform was able to continuously hop forward at 1.82 Hz. The average horizontal hopping distance was 18.7 cm, and the average forward speed was 0.34 m/s. This speed was corresponding to a Froude number of 0.14. The energy consumed for one hop was 2.09 J, and the corresponding energetic cost of transport was 6.43. The combination of inverted cam and cyclic trajectory generation has the potential to be used in other robotic applications, such as flapping wings in the air and tail fin waving in water.

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Leg design for running and jumping dynamics

Cited by 10 publications

References 18 publications

Designing Dynamic Machines With Large-Scale Root Finding

Designing Dynamic Machines With Large-Scale Root Finding

Anisotropic compliance of robot legs improves recovery from swing-phase collisions

Elastic-Actuation Mechanism for Repetitive Hopping Based on Power Modulation and Cyclic Trajectory Generation

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