Mechanical Shock Propagation Reduction in Robot Legs

Singh, Bajwa Roodra Pratap; Featherstone, Roy

doi:10.1109/lra.2020.2966395

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…In ( 17), we can find the motor angle θ m to make a steady state at θ = 0. In addition to ( 16), (17), by assuming the small rotated angle/velocity (θ, θ), the dynamics equation ( 15) can be linearized as…”

Section: Neck Dynamics Analysismentioning

confidence: 99%

“…To reduce impacts or vibrations induced by aggressive motions of legged robots, some studies have focused on inserting compliant components in the legs (e.g., flexible feet [14], elastic actuators [15], [16]) However, these components are not tunable once installed, so the stiffness of the components may be effective in improving state estimation for some locomotions but not for others. Another recent work [17] presents a shock propagation reduction method by optimizing the mass distribution in a robot's leg, which, however, cannot be applied to various gaits since it restricts the ankle angle on landing. On the other hand, an algorithmic method is proposed in [18], which enhances the state estimation during aggressive locomotion by performing multiple visual SLAM sessions that track feature points individually according to the phases of the robot's gait cycle.…”

Section: Introductionmentioning

confidence: 99%

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Tunable Impact and Vibration Absorbing Neck for Robust Visual-Inertial State Estimation for Dynamic Legged Robots

Kim

Lee

2023

IEEE Robot. Autom. Lett.

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Section: Neck Dynamics Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tunable Impact and Vibration Absorbing Neck for Robust Visual-Inertial State Estimation for Dynamic Legged Robots

Kim

Lee

2023

IEEE Robot. Autom. Lett.

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“…Aiming to reduce the initial and post-impact forces, the proprioceptive actuator devised for the MIT Cheetah robot's leg provides a mechanical approach to mitigate impacts without added compliance (Wensing et al 2017). More recently, Singh and Featherstone (2020) proposed a novel quadruped robot leg design that removes the shock propagation from the floating-base. Another strategy absorbs the impacts at foot-strike through passive springs in the ankle (Reher et al 2016).…”

Section: Mitigating Impact Through Hardware Improvementsmentioning

confidence: 99%

Impact-Aware Task-Space Quadratic-Programming Control

Wang¹,

Dehio²,

Tanguy³

et al. 2020

Preprint

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Generating on-purpose impacts with rigid robots is challenging as they may lead to severe hardware failures due to abrupt changes in the velocities and torques. Without dedicated hardware and controllers, robots typically operate at a near-zero velocity in the vicinity of contacts. We assume knowing how much of impact the hardware can absorb and focus solely on the controller aspects. Hybrid controllers with reset maps provided elegant solutions for given impact tasks. The novelty of our approach is twofold: (i) it uses the task-space inverse dynamics formalism that we extend by seamlessly integrating impact tasks; (ii) it does not require separate models with switches or a reset map to operate the robot undergoing impact tasks. Our main idea lies in integrating post-impact states prediction and impactaware inequality constraints as part of our existing general-purpose whole-body controller. To achieve such prediction, we formulate task-space impacts and its spreading along the kinematic and potentially arborescent, structure of a floating-base robot with subsequent joint velocity and torque jumps. As a result, the feasible solution set accounts for various constraints due to expected impacts. In a multi-contact situation of under-actuated legged robots subject to multiple impacts, we also enforce the dynamic equilibrium margins. By design, our controller does not require precise knowledge of impact location and timing. We assessed our formalism with the humanoid robot HRP-4, generating maximum contact velocities, neither breaking established contacts nor damaging the hardware.

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“…Wensing investigates how joint-level apparent inertia decreases backdrivability, and thus, degrades the impact mitigation capability of the whole system [1]. Singh studies how the mass distribution of a robot's leg influences the propagation of impact from the ground to the torso [7]. Kim demonstrated a light-weighted robot arm of high backdrivability with a novel tension-amplification transmission [8].…”

Section: Introductionmentioning

confidence: 99%

The dynamic effect of mechanical losses of transmissions on the equation of motion of legged robots

Sim

Ramos

2021

2021 IEEE International Conference on Robotics and Automation (ICRA)

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Industrial manipulators do not collapse under their own weight when powered off due to the friction in their joints. Although these mechanism are effective for stiff position control of pick-and-place, they are inappropriate for legged robots that must rapidly regulate compliant interactions with the environment. However, no metric exists to quantify the robot's performance degradation due to mechanical losses in the actuators and transmissions. This paper provides a fundamental formulation that uses the mechanical efficiency of transmissions to quantify the effect of power losses in the mechanical transmissions on the dynamics of a whole robotic system. We quantitatively demonstrate the intuitive fact that the apparent inertia of the robots increase in the presence of joint friction. We also show that robots that employ high gear ratio and low efficiency transmissions can statically sustain more substantial external loads. We expect that the framework presented here will provide the fundamental tools for designing the next generation of legged robots that can effectively interact with the world.

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Mechanical Shock Propagation Reduction in Robot Legs

Cited by 11 publications

References 22 publications

Tunable Impact and Vibration Absorbing Neck for Robust Visual-Inertial State Estimation for Dynamic Legged Robots

Tunable Impact and Vibration Absorbing Neck for Robust Visual-Inertial State Estimation for Dynamic Legged Robots

Impact-Aware Task-Space Quadratic-Programming Control

The dynamic effect of mechanical losses of transmissions on the equation of motion of legged robots

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