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Swing

About: Swing is a research topic. Over the lifetime, 17434 publications have been published within this topic receiving 82795 citations.


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Journal ArticleDOI
TL;DR: In this article, the authors considered the swing-up control problem of a two-degree-of-freedom planar robot with a single actuator and gave conditions under which the response of either degree of freedom may be globally decoupled from the response on the other and linearized.
Abstract: Underactuated mechanical systems are those possessing fewer actuators than degrees of freedom. Examples of such systems abound, including flexible joint and flexible link robots, space robots, mobile robots, and robot models that include actuator dynamics and rigid body dynamics together. Complex internal dynamics, nonholonomic behavior, and lack of feedback linearizability are often exhibited by such systems, making the class a rich one from a control standpoint. In this article the author studies a particular underactuated system known as the Acrobot: a two-degree-of-freedom planar robot with a single actuator. The author considers the so-called swing up control problem using the method of partial feedback linearization. The author gives conditions under which the response of either degree of freedom may be globally decoupled from the response of the other and linearized. This result can be used as a starting point to design swing up control algorithms. Analysis of the resulting zero dynamics as well as analysis of the energy of the system provides an understanding of the swing up algorithms. Simulation results are presented showing the swing up motion resulting from partial feedback linearization designs. >

978 citations

Journal ArticleDOI
TL;DR: Results demonstrate that the recovery strategies provided a functionally appropriate response for overcoming the obstacle and maintaining the ongoing locomotion.
Abstract: The movement strategies and the underlying organization of the muscular responses for recovery from a tripping perturbation applied in early and late swing during walking were studied in humans. The latencies of the reflex response (60–140 ms) suggested that polysynaptic pathways are involved. The most common movement outcome was an elevating strategy of the swing limb in response to the early swing perturbation and a lowering strategy in response to the late swing perturbation. The elevating strategy comprised a flexor component of the swing limb and an extensor component of the stance limb. There was a temporal sequencing of the swing limb biceps femoris prior to the swing limb rectus femoris response to remove the limb from the obstacle prior to accelerating the limb over the obstacle. The extensor response of the stance limb generated an early heel-off to increase the height of the body. Thus, the lower limb joints collaborated to increase the height of the centre of mass and provide extra time to extend the swing limb in preparation for the landing. Flexion of the swing limb would be dangerous in response to the late swing perturbation as the swing limb is approaching the ground and the body mass has passed forward of the stance foot. Instead, a lowering strategy was accomplished by inhibitory responses of the swing limb vastus lateralis and/or excitatory responses of the swing limb biceps femoris. Both these responses resulted in a rapid lowering of the limb to the ground with a flat foot or forefoot landing and a shortening of the step length. Thus, in response to the late swing perturbation, the same recovery strategy was achieved by different patterns of muscle activation. These results demonstrate that the recovery strategies provided a functionally appropriate response for overcoming the obstacle and maintaining the ongoing locomotion.

385 citations

Journal ArticleDOI
TL;DR: The product of maximum step frequency and the square root of the stature is approximately constant after 5 years of age and the time of swing initially shows a positive regression with the time for a complete cycle of one leg, but by 4-5 years ofAge the negative linear regression of the adult appears.
Abstract: Fifty males and females between 1 and 35 years of age were studied during locomotion. During the first few months of walking the step frequency bears no apparent relationship to the speed of walking. A log-log regression equation describes the adult relationship better than a linear equation. A few adolescents were better described by a linear equation and either log-log or linear equations can be used for children. The product of maximum step frequency and the square root of the stature is approximately constant after 5 years of age. The time of swing initially shows a positive regression with the time for a complete cycle of one leg. The child abandons this pattern in favour of an approximately constant time of swing and by 4-5 years of age the negative linear regression of the adult appears. The time of swing is usually much less than half the natural period of either the whole leg about the hip or of the lower leg and foot about the knee. The effects of wearing shoes upon step frequency and time of sw...

370 citations

Journal ArticleDOI
TL;DR: This work extracts market information from forward prices and volatilities and builds a pricing framework for swing options based on a one-factor mean-reverting stochastic process for energy prices that explicitly incorporates seasonal effects.
Abstract: In the energy markets, in particular the electricity and natural gas markets, many contracts incorporate flexibility-of-delivery options known as "swing" or "take-or-pay" options. Subject to daily as well as periodic constraints, these contracts permit the option holder to repeatedly exercise the right to receive greater or smaller amounts of energy. We extract market information from forward prices and volatilities and build a pricing framework for swing options based on a one-factor mean-reverting stochastic process for energy prices that explicitly incorporates seasonal effects. We present a numerical scheme for the valuation of swing options calibrated for the case of natural gas.

309 citations

Journal ArticleDOI
TL;DR: In this paper, a mathematical model of the swing phase of walking is presented, where the lower extremities are represented by links, and the rest of the body by a point mass at the hip joint.
Abstract: A mathematical model of the swing phase of walking is presented. The lower extremities are represented by links, and the rest of the body by a point mass at the hip joint. It is assumed that no muscular moments are provided to any of the joints of the extremities during the swing phase. The body then moves under the action of gravity alone. The model analyzed here is an improvement of a previous model by the same authors. The range of possible times of swing for each step length is computed for the model, and the results are compared with published experimental data. Typical histograms of forces applied to the ground and angles of the limbs against time are also given. The computed forces and angles have the same general time course as those found experimentally in normal walking, with the exception of the vertical force. The reasons responsible for this are discussed. The comparison of the results of the model with normal walking also suggests the possible effects that the absent determinants have on gait.

298 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023368
2022820
2021191
2020653
2019825
20181,070