Design and Stability Analysis of a 3D Rimless Wheel with Flat Feet and Ankle Springs

Narukawa, Terumasa; Takahashi, Masaki; Yoshida, Kazuo

doi:10.1299/jsdd.3.258

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…[2] It is worth noting that 2D motion of a rimless wheel which has only one degree of freedom, has been studied before by McGeer and completed by others such as [2,17]. To the best of our knowledge, the only works closely related to the present work are [16,18,19]. But then again they are concentrated on 3D straight walking of the wheel and no attention has been paid to its turning motion.…”

Section: Introductionmentioning

confidence: 79%

Passive turning motion of 3D rimless wheel: novel periodic gaits for bipedal curved walking

2015

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Passive dynamic walking originally was introduced to describe some natural stable periodic gaits in straight walking. However, in this research, we have extended this notion to curved walking, wherein some novel three-dimensional (3D) periodic gaits with natural stability have been realized. For this aim, the simplest bipedal walking model, i.e. a rimless spoked-wheel, in its general 3D form, has been considered on a straight slope surface. Then, two kinds of stable passive turning, i.e. limited and circular continuous have been discussed. The first kind is actually a transfer among two-dimensional (2D) periodic motions and can be implemented on such straight slope surface. It is shown that the second kind is related to novel 3D periodic motions and can be just recognized on a special surface profile namely 'helical slope'. The latter are interpreted as 3D fixed points of a Poincare return map. Results not only show asymptotical stability of such periodic motions, but also surprisingly indicate that the stability of a 3D periodic gait (turning) is higher than 2D one (straight walking). Furthermore, the characteristics of passive turning are shown to be firmly connected with the value of the state variables such as the lean angle in each case.

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Section: Introductionmentioning

confidence: 79%

Passive turning motion of 3D rimless wheel: novel periodic gaits for bipedal curved walking

2015

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“…The consecutive spokes in their model are on alternate sides of the wheel thus taking into account the finite leg separation in humans or robots. Passive walking rimless wheels (on downward incline) with springy feet and visco-elastic legs have been demonstrated (Narukawa et al, 2009;Asano et al, 2012). Rimless wheel actuated by radially expanding legs have also been explored (Asano, 2009;Yan and Agrawal, 2004).…”

Section: The Rimless Wheelmentioning

confidence: 99%

Investigations on Dynamics and Control of a Rimless Wheel based 2D Dynamic Walker using Pulsed Torque Actuation

Patnaik¹

2018

Preprint

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SYNOPSISWheeled systems are energy efficient on prepared surfaces like roads and tracks. Legged systems are capable of traversing different terrains but can be lossy. At low speeds and on off-road surfaces, legged systems using dynamic walking can be efficient. Towards this objective, the dynamics of the walker needs to be modelled and controlled. This thesis presents analysis and experiments on the dynamics and control of a rimless wheel based mobile robot (Chatur ) in a category between wheeled and legged systems. It is effectively a 2D dynamic walker that serves as a platform for investigating inverted pendulum walking. A pulsed actuation torque is proposed for the system resulting in four torque regimes defined by the ratio of energy losses to available actuator torque. Five physical constraints that limit the choice of operating points of a generic inverted pendulum walker are expounded and location of optimal operating points is discussed. Chatur's hardware design is elaborated and a control topology is proposed for pulsed actuation of the dual brushless dc (BLDC) motor driven platform with wheel synchronization.A closed-form analytical solution, using hyperbolic functions, is proposed for the stance phase inverted pendulum dynamics. Suitable models for ground impact and braking losses are used. There are four types of sub-phases within a stance phase -actuated rise, unactuated rise, actuated fall, unactuated fall. These are concatenated in four different ways to form repeating cycles yielding the four torque regimes that are identified by the fraction of stance phase for which the actuator is energized. The experimental set-up is a fixed step-angle walker built using two adjacent rimless wheels independently actuated at the hub. Varying the magnitude and duty ratio of the torque pulse, the proposed regimes are experimentally shown. The mechanical cost of transport is computed for different speeds. Videos of the walks are also taken.The operating point of an inverted pendulum walker can be specified by the combination of initial mid-stance velocity and step angle chosen for a given walk. Using basic mechanics, a framework of physical constraints that defines allowable operating points is presented. For any given speed, the optimal operating point with minimum mechanical power requirement is located based on tangency of the power and velocity contours. Repeating for different speeds, a family of optimal operating points, called the optimal locus, is obtained. Using an appropriate constant step angle over a range of speeds could lead to an inverted pendulum walker that is close to optimal.The hardware design for Chatur and the caveats associated with reliable performance of its mechanical and electrical subsystems are elaborated. In order to ensure lateral stability, the system uses two contralateral wheels driven by separate BLDC hub motors. From a motor drive perspective, the reflected load torque has a characteristic cyclic variation that repeats several times within a mechanical revolution. The proposed ...

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“…In previous studies, we have shown that passive walkers with fiat feet and ankle stifihess can walk down shallow slopes (Narukawa, et al,, 2009a(Narukawa, et al,, , 2009b(Narukawa, et al,, , 2010, In this paper, in order to achieve level-ground walking, we added a torso and two actuators at the hip to the passive walker with fiat feet and ankle stiffAess. Two torques at the hip are applied by actuators to walk stably on level ground.…”

Section: Introductionmentioning

confidence: 98%

2C14 Level-Ground Walking Based on Passive Walk for a Simple Planar Biped with Torso and Flat Feet(The 12th International Conference on Motion and Vibration Control)

Narukawa

Yamamoto

2014

MoViC

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This study is inspired by the passive walking mechanisms which show that stable walking can be realized simply, The passive walkers can only walk on shallow slopes because they use grayitational potential energy in order to recover the energy lost mainly thorough the swing-leg impacts with the ground. The walking speed decreases with the slope angle and it is almost irnpossible to walk on level ground. We propose a level-ground walking method for a biped walker based on passive walking mechanisms, however two actuators are added at the hip in order to walk on level ground. The torso is added to the biped walker and the torque required to hold the leaning toTso is used to walk on level ground. A swingleg control is introduced to modify the free pendulum motion of the swing-Ieg in order to avoid falling forward. Numerical simulations show that ankle stiffuess helps the walker to walk more eMciently.

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Design and Stability Analysis of a 3D Rimless Wheel with Flat Feet and Ankle Springs

Cited by 14 publications

References 10 publications

Passive turning motion of 3D rimless wheel: novel periodic gaits for bipedal curved walking

Passive turning motion of 3D rimless wheel: novel periodic gaits for bipedal curved walking

Investigations on Dynamics and Control of a Rimless Wheel based 2D Dynamic Walker using Pulsed Torque Actuation

2C14 Level-Ground Walking Based on Passive Walk for a Simple Planar Biped with Torso and Flat Feet(The 12th International Conference on Motion and Vibration Control)

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