An adaptive shock mitigation control method for helicopter seat system with magnetorheological energy absorbers

2021 ◽  
pp. 1045389X2110387
Author(s):  
Zhongqiang Feng ◽  
Zhaobo Chen ◽  
Xudong Xing
Keyword(s):  
Control Method ◽  
Selection Criterion ◽  
Threshold Value ◽  
Damping Force ◽  
Comparative Performance ◽  
Bingham Number ◽  
Control Stage ◽  
Shock Mitigation ◽  
Energy Absorbers ◽  
Maximum Deceleration

This research presents a minimal maximum deceleration (MMD) control method which can be used in the shock mitigation system with magnetorheological energy absorbers (MREAs). The proposed control method can make the payload stop at the end of the available MREA stroke with the lowest maximum deceleration, which does not exceed the deceleration threshold value and lead to the lowest occupant injury probability. The shock mitigation system controlled by MMD will experience constant deceleration control stage and maximum damping force control stage while making full use of the available MREA stroke. The comparative performance of the MMD control method with Bingham number (BN) control, constant deceleration (CD) control and minimum duration deceleration exposure (MDDE) control is shown. Then, the controllable drop velocity range and the required maximum MREA controllable damping force range of MMD control method is calculated. Subsequently, the optimal control method selection criterion among BN control method, CD control method and MMD control method is developed. Finally, the optimal selection criterion is applied to the drop induced shock mitigation system with varying payload velocity, payload mass (occupant type) and the maximum controllable damping force of MREA.

A minimum transmitted load control method for shock isolation mounts with magnetorheological energy absorbers

2021 ◽  
pp. 1045389X2110643
Author(s):  
Zhongqiang Feng ◽  
Dong Yu ◽  
Zhaobo Chen ◽  
Xudong Xing ◽  
Hui Yan
Keyword(s):  
Control Method ◽  
Selection Criterion ◽  
Soft Landing ◽  
Damping Force ◽  
Single Degree Of Freedom ◽  
Bingham Number ◽  
Optimal Control Method ◽  
Shock Isolation ◽  
Energy Absorbers ◽  
The Relationship

This paper proposed a minimum transmitted load (MTL) control method for drop-induced shock isolation mounts (SIM) with magnetorheological energy absorbers (MREAs). MTL control method consists of two parts of maximum damping force (MDF) control and one part of constant acceleration (CA) control, which can make the payload stop after fully utilize MREA stroke (soft landing) with minimum transmitted load. The control algorithm of MTL control method is derived in a single-degree-of-freedom (SDOF) system. The relationship between the controllable velocity range of MTL control method and parameters of shock isolation mounts is also derived. An optimal control method selection criterion between Bingham number (BN) control method and MTL control method is developed. The performance of MTL control method and selection criterion are shown by applying to the SIM system with variable drop velocities and system parameters. Results shows that MTL control method has the minimum transmitted load and the selection criterion is feasible.

Adaptive magnetorheological energy absorber control method for drop-induced shock mitigation

2020 ◽  
pp. 1045389X2095710
Author(s):  
Mukai Wang ◽  
Zhaobo Chen ◽  
Norman M Wereley
Keyword(s):  
Control Method ◽  
Selection Criterion ◽  
Soft Landing ◽  
Energy Absorber ◽  
Bingham Number ◽  
Seat Suspension ◽  
Shock Mitigation ◽  
Optimal Control Method ◽  
Control Goal ◽  
Optimal Criterion

This paper presents a minimum duration deceleration exposure (MDDE) control method for drop-induced shock mitigation system using a magnetorheological energy absorber (MREA) at high sink rates. The key MDDE control goal is that the payload should come to rest after fully using the available MREA stroke, that is, to accomplish a soft landing, without exceeding the maximum allowable deceleration and simultaneously minimizing the duration of exposure to the maximum allowable deceleration. The MDDE control algorithm is developed as follows for a given available stroke. The payload deceleration is initially set to the maximum allowable value and held constant until the remaining damper stroke and payload velocity are such that the Bingham number control can be used for the terminal trajectory to ensure a soft landing. The sink rate range of the MDDE control is calculated and the results show that the MDDE control can be utilized at high sink rates, whereas prior Bingham number control can be used only at sufficiently low sink rates without violating the maximum allowable deceleration constraint. An optimal criterion to switch from the BN control method to MDDE control method is developed. Finally, the optimal control method is applied for a helicopter seat suspension system by optimal selection criterion to automatically accommodate varying sink rate (drop velocity) and occupant weight.

An improved constant deceleration control method with extended shock velocity range for magnetorheological energy absorber

2021 ◽  
pp. 1045389X2110572
Author(s):  
Zhongqiang Feng ◽  
Dong Yu ◽  
Zhaobo Chen ◽  
Xudong Xing ◽  
Hui Yan
Keyword(s):  
Control Algorithm ◽  
Control Method ◽  
Velocity Range ◽  
Damping Force ◽  
Isolation System ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Shock Mitigation ◽  
Energy Absorbers ◽  
Feasible Solutions

This paper proposed an extended constant deceleration (ECD) control method that can be used in the shock mitigation system with magnetorheological energy absorbers (MREAs). The ECD control method has three sections: zero controllable force (ZCF) section, constant deceleration (CD) section, and maximum damping force (MDF) section. Under the control of ECD, the system can stop at the end of MREA stroke without exceeding the maximum allowable deceleration. The ECD control algorithm is derived in a single-degree-of-freedom (SDOF) system. The controllable velocity range and the required controllable damping force of ECD control method are also derived, which can provide feasible solutions for the design of shock isolation system with MREAs. The performance of ECD control method is shown by applying to the drop-induced shock mitigation system with different drop velocities, different maximum controllable damping force, and MREA stroke. The results shows that the ECD control method not only has a large controllable velocity range and small controllable damping force requirement, but also can minimize the load transmitted to the system.

Optimal control of drop-induced shock mitigation using magnetorheological energy absorbers considering quadratic damping

2021 ◽  
pp. 1045389X2199392
Author(s):  
Mukai Wang ◽  
Zhaobo Chen ◽  
Hui Yan ◽  
Young-Tai Choi ◽  
Norman M Wereley
Keyword(s):  
Optimal Control ◽  
Control Algorithm ◽  
Control Method ◽  
Soft Landing ◽  
Minimum Duration ◽  
Single Degree Of Freedom ◽  
Bingham Number ◽  
Shock Mitigation ◽  
Energy Absorbers ◽  
Quadratic Damping

The optimal control of a magnetorheological energy absorber (MREA) shock mitigation system is investigated considering quadratic damping in the MREA. To this end, the equation of motion of a single-degree-of-freedom (SDOF) shock suspension system using an MREA with quadratic damping is analyzed. To achieve a soft landing and to maintain stroking load below a maximum allowable value, it is required that the payload comes to rest after fully utilizing the available stroke. For low sink rates, a generalized Bingham number (quadratic) or GBN-Q control algorithm is developed that achieves a soft landing by selecting an initial magnetorheological (MR) force level or generalized Bingham number (GBN) for the quadratic damping at the initial sink rate. To cope with the cases above a critical sink rate, where the deceleration exceeds a maximum allowable threshold when using the GBN-Q control only, a minimum duration deceleration exposure-quadratic (MDDE-Q) controller is developed. This controller seeks to maintain the stroking load at its maximum allowable threshold until the payload slows such that the GBN-Q controller can be used to achieve the soft landing condition. The switching methodology between the GBN-Q controller and the MDDE-Q controller is discussed. Each control method relies on an optimal GBN that is computed to ensure a soft landing. Results show that the MDDE-Q controller can successfully minimize the exposure of the payload to the maximum allowable stroking load.

Drop-Induced Shock Mitigation Using Adaptive Magnetorheological Energy Absorbers Incorporating a Time Lag

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Equations Of Motion ◽  
Time Lag ◽  
Soft Landing ◽  
Single Degree Of Freedom ◽  
Bingham Number ◽  
Shock Mitigation ◽  
Payload Mass ◽  
Energy Absorbers ◽  
Time Required ◽  
The Impact

This study addresses the nondimensional analysis of drop-induced shock mitigated using magnetorheological energy absorbers (MREAs) incorporating a time lag. This time lag arises from two sources: (1) the time required to generate magnetic field in the electromagnet once current has been applied and (2) the time required for the particles in the magnetorheological fluid to form chains. To this end, the governing equations of motion for a single degree-of-freedom (SDOF) system using an MREA with a time lag were derived. Based on these equations, nondimensional stroke, velocity, and acceleration of the payload were derived, where the MREA with a time lag was used to control payload deceleration after the impact. It is established that there exists an optimal Bingham number that allows the payload mass to achieve a soft landing, that is, the payload comes to rest after utilizing the available stroke of the MREA. Finally, the shock mitigation performance when using this optimal Bingham number control strategy is analyzed, and the effects of time lag are quantified.

Optimal Control of Vertically Stroking Crew Seats Employing Magnetorheological Energy Absorbers

2009 ◽  
Author(s):  
Harinder J. Singh ◽  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Optimal Control ◽  
Impact Velocity ◽  
Vibration Isolation ◽  
Viscous Force ◽  
Bingham Number ◽  
Shock Mitigation ◽  
Feasible Range ◽  
Shock Event ◽  
Damper Design ◽  
Energy Absorbers

Nondimensional analyses of vertical stroking crew seats with adaptive nonlinear magnetorheological energy absorbers (MREA) and magnetorheological shock isolation (MRSI) were addressed in this study. Under consideration were single-degree-of-freedom vertically stroking seat systems consisting of a rigid occupant mass falling with prescribed initial impact velocity (sink rate). The governing equations of the vertical stroking crew seats were derived using nondimensional variables such as nondimensional stroke, velocity, acceleration and time constant, as well as nondimensional Bingham number (i.e., the ratio of MR yield force to viscous force). The critical Bingham number was defined as that Bingham number for which the available stroke was fully utilized and the seat reaches zero velocity at the end of stroke. This was done in order to maximize shock mitigation performance. Two cases were studied: (1) the MREA problem, or the case where no spring was employed in the suspension, so that the seat was used for a single shock event, (2) the MRSI problem, or the case where a spring was employed in the suspension, so that after the initial shock event, the suspension could be used for either vibration isolation or mitigation of subsequent shock events. Nondimensional displacement, velocity and acceleration were analyzed for MREA and MRSI vertical stroking crew seats for three different payload masses of 47, 77 and 97 kg corresponding to 5th percentile (%tile) female, 50th %tile and 95th %tile male, respectively, with initial impact velocities of 4, 5 and 6 m/s. An optimal control solution was derived for both the MREA and MRSI cases. The effects of payload mass and initial impact velocity on the optimal responses of the vertical stroking crew seats were analyzed for a feasible range of Bingham number based on a realistically constrained (in diameter and volume) MR damper design.

Adaptive Control of a Sliding Seat Using Magnetorheological Energy Absorbers

2010 ◽  
Author(s):  
Min Mao ◽  
Norman M. Wereley ◽  
Alan L. Browne
Keyword(s):  
Adaptive Control ◽  
Degrees Of Freedom ◽  
Adaptive Controller ◽  
Degree Of Freedom ◽  
Lumped Mass ◽  
Adaptive Controllers ◽  
Bingham Number ◽  
Control Objective ◽  
Payload Mass ◽  
Energy Absorbers

Feasibility of a sliding seat utilizing adaptive control of a magnetorheological (MR) energy absorber (MREA) to minimize loads imparted to a payload mass in a ground vehicle for frontal impact speeds as high as 7 m/s (15.7 mph) is investigated. The crash pulse for a given impact speed was assumed to be a rectangular deceleration pulse having a prescribed magnitude and duration. The adaptive control objective is to bring the payload (occupant plus seat) mass to a stop using the available stroke, while simultaneously accommodating changes in impact velocity and occupant mass ranging from a 5th percentile female to a 95th percentile male. The payload is first treated as a single-degree-of-freedom (SDOF) rigid lumped mass, and two adaptive control algorithms are developed: (1) constant Bingham number control, and (2) constant force control. To explore the effects of occupant compliance on adaptive controller performance, a multi-degree-of-freedom (MDOF) lumped mass biodynamic occupant model was integrated with the seat mass. The same controllers were used for both the SDOF and MDOF cases based on SDOF controller analysis because the biodynamic degrees of freedom are neither controllable nor observable. The designed adaptive controllers successfully controlled load-stroke profiles to bring payload mass to rest in the available stroke and reduced payload decelerations. Analysis showed extensive coupling between the seat structures and occupant biodynamic response, although minor adjustments to the control gains enabled full use of the available stroke.

scholarly journals MR Damper-Based Vibration Suppression Method for Control Moment Gyroscope

2018 ◽  
Vol 36 (5) ◽  
pp. 884-889
Author(s):  
Wendong Wang ◽  
Xing Ming ◽  
Yang Chu ◽  
Minghui Liu ◽  
Yikai Shi
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Vibration Suppression ◽  
Control Method ◽  
Magnetorheological Damper ◽  
Magnetic Flux Density ◽  
Damping Force ◽  
Control Moment Gyroscope ◽  
Control Moment ◽  
Suppression Method

To restrain the interference of micro-vibration caused by Control Moment Gyroscope, a new control method based on Magnetorheological damper was proposed in this paper. A mechanical model based on the structure of the presented design was built, and the semi-active control algorithm of damping force was proposed for the designed Magnetorheological damper. The magnetic flux density and other magnetic field parameters were considered and analyzed in Maxwell, and also the related hardware circuit which implements the control algorithm was prepared to test the presented design and algorithm. The results of simulation and experiments show that the presented Magnetorheological damper model and semi-active control algorithm can complete the requirements, and the vibration suppression method is efficient for Control Moment Gyroscope.

scholarly journals Mean-Based Breakpoint Selection on Circular Histogram

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jiulun Fan ◽  
Jipeng Yang
Keyword(s):  
Selection Criteria ◽  
Color Image ◽  
Selection Criterion ◽  
Threshold Value ◽  
Simple Expression ◽  
Circular Data ◽  
Cumulative Distribution ◽  
Color Model ◽  
Hsi Color Model ◽  
Selection Of

Circular histogram represents the statistical distribution of circular data; the H component histogram of HSI color model is a typical example of the circular histogram. When using H component to segment color image, a feasible way is to transform the circular histogram into a linear histogram, and then, the mature gray image thresholding methods are used on the linear histogram to select the threshold value. Thus, the reasonable selection of the breakpoint on circular histogram to linearize the circular histogram is the key. In this paper, based on the angles mean on circular histogram and the line mean on linear histogram, a simple breakpoint selection criterion is proposed, and the suitable range of this method is analyzed. Compared with the existing breakpoint selection criteria based on Lorenz curve and cumulative distribution entropy, the proposed method has the advantages of simple expression and less calculation and does not depend on the direction of rotation.

Realization of desired damping characteristics based on an open-loop-controlled magnetorheological damper

2021 ◽  
pp. 107754632110388
Author(s):  
Hongwei Lu ◽  
Zhifei Zhang ◽  
Yansong He ◽  
Zhi Li ◽  
Jujiang Xie ◽  
...  
Keyword(s):  
Control System ◽  
Control Method ◽  
Characteristic Curve ◽  
Mr Damper ◽  
Open Loop ◽  
Low Noise ◽  
Magnetorheological Damper ◽  
Bench Test ◽  
Damping Force ◽  
Damping Characteristics

The realization of the desired damping characteristics based on magnetorheological (MR) dampers is important for semi-active control and useful for the matching process of suspension damper. To reduce the cost of the control system and improve the output accuracy of the desired damping force, this study proposes an open-loop control method featuring an accurate inverse model of the MR damper and a tripolar current driver. The reversible sigmoid model is used to accurately and quickly calculate the desired current. Furthermore, the change characteristic of the desired current is analyzed qualitatively and quantitatively, which shows that the desired current needs to change suddenly to make the actual damping force velocity curve quickly approach the desired one. To meet the demand of the desired current, a tripolar current driver controlled by an improved PI control algorithm is proposed, which is with fast response and low noise. Finally, the bench test verifies that the control system can achieve different desired damping characteristics well, and the inherent error in this process is explained through the gap between the available damping force area and the desired damping characteristic curve and the crossover phenomenon of the dynamic characteristic curves of the MR damper.

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