Dynamics and stability of a rimless spoked wheel: a simple 2D system with impacts

Coleman, Michael J.

doi:10.1080/14689360903429238

Cited by 37 publications

(29 citation statements)

References 16 publications

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“…Moreover, the sinkage of each wheel-leg was estimated using the output of the IR according to the method presented in [15] in order to estimate the same soil characteristics using Eq. (29).…”

Section: A Load Bearing and Shear Strength Characterization Resultsmentioning

confidence: 99%

“…This table also includes other wheel-leg simulation parameters including rotation speed (ω). Given its low value and the high deformability of the terrain, the dynamic effects of the impacts between the legs and the ground, commonly addressed in studies for wheelleg metastability on rigid floors [29], are not discussed within the scope of this paper.…”

Section: A Generalized Terradynamics For Multi-legged Wheel-legsmentioning

confidence: 99%

“…This leads to the soil characterization system with transformation matrix Φ S shown in Eq. (29), which yields the two main shear and load bearing characteristics of the soil from midstance wheel-leg sinkage.…”

Section: B Sinkage-based Characterizationmentioning

confidence: 99%

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Models for Slip Estimation and Soft Terrain Characterization With Multilegged Wheel–Legs

Comin

Saaj

2017

IEEE Trans. Robot.

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Abstract-Successful operation of off-road mobile robots faces the challenge of mobility hazards posed by soft, deformable terrain, e.g. sand traps. The slip caused by these hazards has a significant impact on tractive efficiency, leading to complete immobilization in extreme circumstances. This paper addresses the interaction between dry frictional soil and the multi-legged wheelleg concept, with the aim of exploiting its enhanced mobility for safe, in-situ terrain sensing. The influence of multiple legs and different foot designs on wheel-leg-soil interaction is analyzed by incorporating these aspects to an existing terradynamics model. In addition, new theoretical models are proposed and experimentally validated to relate wheel-leg slip to both motor torque and stick-slip vibrations. These models, capable of estimating wheelleg slip from purely proprioceptive sensors, are then applied in combination with detected wheel-leg sinkage to successfully characterize the load bearing and shear strength properties of different types of deformable soil. The main contribution of this paper enables non-geometric hazard detection based on detected wheel-leg slip and sinkage.

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Section: A Load Bearing and Shear Strength Characterization Resultsmentioning

confidence: 99%

Section: A Generalized Terradynamics For Multi-legged Wheel-legsmentioning

confidence: 99%

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Models for Slip Estimation and Soft Terrain Characterization With Multilegged Wheel–Legs

Comin

Saaj

2017

IEEE Trans. Robot.

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“…In the collision phase we assume that the rear leg frame at impact (the previous stance leg) begins to leave the ground immediately after the landing of the fore leg frame (the next stance leg) according to the law of inelastic collision. Thus based on the research of Coleman [10], the transition equation for the angular velocity becomeṡ…”

Section: Collision Equationmentioning

confidence: 99%

“…Considering that the steady walking speed can be calculated by the ratio of the step length to the step period of the RW, therefore, a target steady walking speed can be generated by calculating the angle of the slope. Furthermore, Coleman found analytic approximations for the minimum required slope for stable rolling in three dimensions [9,10], which helped us to generate the lowest walking speed as a critical condition.…”

Section: Introductionmentioning

confidence: 99%

Analysis of steady and target walking speeds in limit cycle walking

Xiao

Asano

2015

Int. J. Dynam. Control

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This paper presents the mathematical analysis of steady walking speed and target walking speed generation in 1-DOF limit cycle walking driven by time-settling control inputs. An actuated combined rimless wheel (CRW) model is introduced to analyse the steady walking state when the CRW is walking on level ground. First the initial and terminal boundary conditions driven by discrete stepwise control systems are analysed. The steady step period can be calculated and the target walking period can be generated by the formulas. Second we extend the mathematical analysis to (n + 1)-period stepwise control system and derive the general formula of the steady step period. Finally, the continuous piecewise control systems are analysed mathematically by discretizing the control input, and thus the boundary conditions can be analysed by the formula of (n + 1)-period stepwise control system. As a result, if the generated walking gait is single-step-cycle, the steady step period can be calculated and target walking steady speeds can be generated by our general formulas in the time-settling control systems.

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Trafficability Assessment of Deformable Terrain through Hybrid Wheel‐Leg Sinkage Detection

Comin

Lewinger

Saaj

et al. 2016

Journal of Field Robotics

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Off-road ground mobile robots are widely used in diverse applications, both in terrestrial and planetary environments. They provide an efficient alternative, with lower risk and cost, to explore or to transport materials through hazardous or challenging terrain. However, nongeometric hazards that cannot be detected remotely pose a serious threat to the mobility of such robots. A prominent example of the negative effects these hazards can have is found on planetary rover exploration missions. They can cause a serious degradation of mission performance at best and complete immobilization and mission failure at worst. To tackle this issue, the work presented in this paper investigates the novel application of an existing enhanced-mobility locomotion concept, a hybrid wheel-leg equipped by a lightweight micro-rover, for in situ characterization of deformable terrain and online detection of nongeometric hazards. This is achieved by combining an improved vision-based approach and a new ranging-based approach to wheel-leg sinkage detection. In addition, the paper proposes an empirical model, and a parametric generalization, to predict terrain trafficability based on wheel-leg sinkage and a well-established semiempirical terramechanics model. The robustness and accuracy of the sinkage detection methods implemented are tested in a variety of conditions, both in the laboratory and in the field, using a single wheel-leg test bed. The sinkage-trafficability model is developed based on experimental data using this test bed and then validated onboard a fully mobile robot through experimentation on a range of dry frictional soils that covers a wide spectrum of macroscopic physical characteristics

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Dynamics and stability of a rimless spoked wheel: a simple 2D system with impacts

Cited by 37 publications

References 16 publications

Models for Slip Estimation and Soft Terrain Characterization With Multilegged Wheel–Legs

Models for Slip Estimation and Soft Terrain Characterization With Multilegged Wheel–Legs

Analysis of steady and target walking speeds in limit cycle walking

Trafficability Assessment of Deformable Terrain through Hybrid Wheel‐Leg Sinkage Detection

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