Search results for "Backlash"
showing 7 items of 7 documents
Piecewise Affine (PWA) Modeling and Switched Damping Control of Two-Inertia Systems with Backlash
2018
Backlash degrades positioning accuracy and can induce mechanical wear and breakage by collisions. Therefore, a lot of studies have been conducted on backlash compensation. The simplest control method for the impact attenuation is torsional damping addition by feedback of torsional velocity. This paper reveals the advantages and disadvantages of the torsional damping addition. Based on the analyses, a novel switched damping control is proposed to realize the responses with smaller overshoot while attenuating the impact. The mechanical system and the proposed controller are described as piecewise affine systems for analyses. The performance of the proposed method is compared with a linear dam…
Model-Free Sliding-Mode-Based Detection and Estimation of Backlash in Drives With Single Encoder
2021
Backlash is a frequently encountered problem for various drives, especially those equipped with a single encoder onside of the controlled actuator. This brief proposes a sliding-mode differentiator-based estimation of unknown backlash size while measuring the actuator displacement only. Neither actuator nor load dynamics are explicitly known, while a principal second-order actuator behavior is assumed. We make use of the different perturbation dynamics distinctive for different backlash modes and an unbounded impulse-type perturbation at impact. The latter leads to transient loss of the sliding-mode and allows for detecting an isolated time instant of the backlash occurrence. The proposed m…
Backlash Identification in Two-Mass Systems by Delayed Relay Feedback
2019
Backlash, also known as mechanical play, is a piecewise differentiable nonlinearity which exists in several actuated systems, comprising, e.g., rack-and-pinion drives, shaft couplings, toothed gears, and other machine elements. Generally, the backlash is nested between the moving parts of a complex dynamic system, which handicaps its proper detection and identification. A classical example is the two-mass system which can approximate numerous mechanisms connected by a shaft (or link) with relatively high stiffness and backlash in series. Information about the presence and extent of the backlash is seldom exactly known and is rather conditional upon factors such as wear, fatigue and incipien…
Backlash against the procedural consensus
2020
While the politics of backlash is typically described as a reaction to policy decisions in favour of minority rights, immigration or globalisation, this essay focuses on the fact that backlash typically also involves a reaction against the procedural consensus liberal democracy is based upon. This challenge to democratic procedures and institutions may be even more dangerous in its effects than the substantial objectives of backlash. I use the composite definition of backlash suggested by Alter and Zürn to assess in how far the attacks on the institutions of liberal democracy have retrograde objectives in themselves or in how far they are merely instrumental to the pursuit of other retrogr…
Self-censorship and Shifting Cognitions of Offence in the Stand-up Acts of Basket Mouth and Trevor Noah
2021
With social media taking stand-up routines beyond their hitherto localised environments, there is growing irritation and backlash against comedians who supposedly tell unpleasant (or offensive) jok...
Trade shocks and the nationalist backlash in political attitudes: panel data evidence from Great Britain
2021
This article leverages individual-level panel data on nationalist attitudes to contribute to the debate on the (economic) roots of popular opposition to globalization. We propose a ���nationalist backlash��� hypothesis: Individuals living in regions suffering from stronger import competition form more nationalist attitudes as part of a broad counter-reaction to globalization. Analyzing data from the British Household Panel Study (BHPS), we document not only a decrease in support for EU membership but also a general shift towards more nationalist attitudes among respondents from regions exposed to higher imports from low-wage countries���in particular, China. We thus uncover a direct individ…
On stiffness and damping of vibro-impact dynamics of backlash
2021
We consider the instantaneous stiffness and damping of the vibro-impact in a backlash pair. Opposed to the existing and mostly used models of the backlash, we address the problem of contact and separation, and the associated force propagation within a mechanical pair, from a viewpoint of the vibro-impact dynamics. We discuss the impact forces with the coefficient of restitution as a principal factor which shapes the transient backlash response.We show that a common approach to modeling the backlash by means of a dead-zone in a restoring force is unsuitable for correctly capturing the mechanical impact. We exemplary demonstrate a qualitative accord between an experimental backlash response a…