Optimal control for soft-landing in elevator emergency crash using multiple magnetorheological shock absorbers

Abstract

Protecting the occupants from surviving the casualties and severe injuries in elevator emergency crashes is always essential. This paper aims to explore the feasibility of using multiple magnetorheological shock absorbers (M-MRSAs) to attain the soft landing of a full-load elevator under impact velocities ranging up to 32 m/s. The resistance forces of MRSA with a bi-fold structure are predicted by evaluating the pressure drops using a nonlinear Bingham-plastic model considering the effects of minor loss. The optimal control for an M-MRSAs system achieving robustness concerning different mass loadings and impact velocities is investigated by formulating a multi-objective problem to minimize the induced peak acceleration with constrained time duration. The results demonstrate that the self-adapting MR yield force provides a smooth operation by minimizing the cycles of re-crash and rebound without incurring an end-stop impact. Furthermore, a plateau behavior of acceleration-displacement profiles is realized to effectively reduce the load transmission from overshoot accelerating force to the protected occupants and eliminate the injury risk.

Adaptive magnetorheological fluid energy absorption systems: a review

“…In the last decade, researchers have tried to apply MREAs to absorb impact energy adaptively and protect personnel, structures and equipment in high-speed impact conditions, such as helicopter seat suspensions (Choi and Wereley 2005), automobile seat suspensions (Mao 2011, Bai andYang 2019), planetary lander (Maeda et al 2019), automobile longitudinal impact energy absorbing device (Woo et al 2007), artillery/machine gun recoil system (Ahmadian and Poynor 2001, Ahmadian et al 2003, Li et al 2019 and emergency collision buffer devices for elevators, etc (Cheng et al 2022, Shen et al 2022, Zheng et al 2022, Christie et al 2023. According to the form of excitations, Shou (2020) defined shock and vibration conditions.…”

Magnetorheological semi-active shock mitigation control: Part II: System extension and application analysis

“…The shock mitigation control system based on magnetorheological (MR) energy absorber (EA) has drawn great interest thanks to the advantages of low power consumption, short response time, simple structure, and continuously controllable damping force (Bai et al, 2019a(Bai et al, , 2019bDutta and Chakraborty, 2014). Various control methods have been applied to MR semi-active shock mitigation control system, such as optimal control (Zheng et al, 2022), robust adaptive control (Nguyen et al, 2018), modified linear quadratic regulator control (Zhao et al, 2019), fuzzy control (Fu et al, 2019), H-infinite control (Ding et al, 2022), bang-bang current control and continuous current control (Choi et al, 2016;Wu and Griffin, 1997). Wang et al (2019) compared the landing performances of an aluminum honeycomb lander and a semiactive control lander and proved that the MREA-based semi-active control method can effectively reduce the maximum acceleration and maximum compression ratio during landing.…”