Legged Robots

Semini, Claudio; Wieber, Pierre-Brice

doi:10.1007/978-3-642-41610-1_59-1

Cited by 5 publications

(5 citation statements)

References 60 publications

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“…Considering the exponential stability definition previously given, it is possible to insert constraints relative to the velocity of convergence. Formally, we can change Equation (8) such that:…”

Section: Stability Theory: Lyapunov Functionsmentioning

confidence: 99%

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Stability and Safety Learning Methods for Legged Robots

Arena,

Li Noce,

Patanè

2024

Robotics

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Learning-based control systems have shown impressive empirical performance on challenging problems in all aspects of robot control and, in particular, in walking robots such as bipeds and quadrupeds. Unfortunately, these methods have a major critical drawback: a reduced lack of guarantees for safety and stability. In recent years, new techniques have emerged to obtain these guarantees thanks to data-driven methods that allow learning certificates together with control strategies. These techniques allow the user to verify the safety of a trained controller while providing supervision during training so that safety and stability requirements can directly influence the training process. This survey presents a comprehensive and up-to-date study of the evolving field of stability certification of neural controllers taking into account such certificates as Lyapunov functions and barrier functions. Although specific attention is paid to legged robots, several promising strategies for learning certificates, not yet applied to walking machines, are also reviewed.

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Section: Stability Theory: Lyapunov Functionsmentioning

confidence: 99%

“…It is crucial to determine the position of its feet and avoid falls when reaching its destination. This challenge arises from the fact that locomotion requires contact forces with the environment, which are constrained by the mechanical laws of contact and the limits of robot actuation [8].…”

Section: Introductionmentioning

confidence: 99%

Stability and Safety Learning Methods for Legged Robots

Arena,

Li Noce,

Patanè

2024

Robotics

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“…Inspired by these creatures, researchers had designed a variety of legged robots [1] which possessed better mobility and adaptability to terrain irregularities than wheeled robots [2]. In the last decades, a significant number of multi-legged robots [3][4][5][6] were developed, inspired by dogs, cockroaches, spiders, and crabs for operating in the unstructured environment. For example, the BigDog built by Boston Dynamics could travel in outdoor steep and rough terrains [7].…”

Section: Introductionmentioning

confidence: 99%

Crab-inspired compliant leg design method for adaptive locomotion of a multi-legged robot

Zhang¹,

Liu

Zhou³

et al. 2022

Bioinspir. Biomim.

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Chinese mitten crab has unique limb structures composed of a hard exoskeleton and flexible muscles. They enable the crab to locomote adaptively and safely on various terrains. In this work, we investigated the limb structures, motion principle, and gaits of the crab using a high-speed camera and a press machine. Then, a novel compliant robot leg design method is proposed, inspired by the crab limb. The leg comprises six hard scleromeres and a flexible thin-wall spring steel sheet (FSSS) mimicking the exoskeleton and muscle. The scleromeres connected one by one with rotational joints are designed with slots. The front end of the FSSS is fixed on the scleromere close to the ground. The rear end crosses the slots and is mounted at the shaft of a linear actuator installed at the rear scleromere. The leg bends and stretches when the actuator pushes and pulls the FSSS, respectively. The kinematic modeling, rigid-flexible coupling dynamic simulations, and leg prototype tests are conducted, which verify the leg design approach. Thirdly, we put forward a multi-legged robot with eight compliant legs and design its gait using the gaits of the crab. Finally, the robot’s performance is evaluated, including the capabilities of walking on different terrains at adjustable speeds and body heights, traversing low channels, walking on slopes, and carrying loads. The results prove that the single-motor-actuated compliant legs and their dynamic coupling with the rigid robot body frame can enable them to have the ground clearance ability and realize the adaptive walking of the robot. The leg design methodology can be used to design multi-legged robots with the merits of compact, light, low mechanical complexity, high safety, and easy to control, for many applications, such as environmental monitoring, search and rescue.

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“…Whether using these to change the angle of a joint of a robotic manipulator, to drive a vehicle's traction system, or even to rotate the sensor of a LiDAR (Light Detection and Ranging), there are numerous uses for these in robotics. Another example are the legged-robotic vehicles that can be found in [1]. However, they have a non-linear behavior that results from the fact that they cannot rotate at any supply voltage, always having a minimum rotation torque (starting torque) that prevents rotation until a when a certain voltage is reached, which is commonly denominated by the motor dead zone.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Control of a DC Motor Coupled to a Non-Rigid Joint

Pinto

Gonçalves

Costa

2020

ASI

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Throughout this paper, the model, its parameter estimation and a controller for a solution using a DC motor with a gearbox worm, coupled to a non-rigid joint, will be presented. First, the modeling of a non-linear system based on a DC Motor with Worm Gearbox coupled to a non-rigid joint is presented. The full system was modeled based on the modeling of two sub-systems that compose it—a non-rigid joint configuration and the DC motor with the worm gearbox configuration. Despite the subsystems are interdependent, its modelling can be performed independently trough a carefully chosen set of experiments. Modeling accurately the system is crucial in order to simulate and know the expected performance. The estimation process and the proposed experimental setup are presented. This setup collects data from an absolute encoder, a load cell, voltage and current sensors. The data obtained from these sensors is presented and used to obtaining some physical parameters from both systems. Finally, through an optimization process, the remaining parameters are estimated, thus obtaining a realistic model of the complete system. Finally, the controller setup is presented and the results obtained are also presented.

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Legged Robots

Cited by 5 publications

References 60 publications

Stability and Safety Learning Methods for Legged Robots

Stability and Safety Learning Methods for Legged Robots

Crab-inspired compliant leg design method for adaptive locomotion of a multi-legged robot

Modeling and Control of a DC Motor Coupled to a Non-Rigid Joint

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