scholarly journals Evaluation of an Improved Suspension System Concept for Surgical Luminaires

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
Arjan J. Knulst ◽  
Jan Jouke Harms ◽  
Jenny Dankelman
Keyword(s):  
Operating Room ◽  
Conceptual Design ◽  
Spatial Orientation ◽  
Movement Patterns ◽  
Suspension System ◽  
Suspension Systems ◽  
Alternative System ◽  
System Concept ◽  
Nasa Tlx ◽  
User Experiment

Abstract Surgeons have indicated ergonomic problems with the surgical luminaire, which have been observed to occur during repositioning. The possibility of singularity, within the movement space of the translational subsystem of the current double-arm suspension systems, is confirmed to be the cause of these problems. In this study, a redesign of the translational subsystem is compared to the conventional translational subsystem. A user experiment with 14 participants is setup to compare the redesigned and alternative system. The experiment is performed outside the operating room (OR), with one setup that can be altered between two designs; an uncoupled state with the kinematics of the conventional subsystem, and a coupled state with the redesigned kinematics. Work cost, duration, and jerk cost are compared, as well as NASA TLX score. The work cost of a movement in the conventional uncoupled state is confirmed to depend on the spatial orientation of the mechanism, which is not the case in the new coupled state. Due to these different kinetics, the movement patterns with the coupled mechanism are more consistent between participants, the duration of movements is shorter, less problems occur, and participants are able to better control the movements as demonstrated by lower jerk costs. This result validates the redesign and confirms the hypothesis that a translational subsystem without the possibility of singularity within its movement space will improve luminaire repositioning. The conceptual design can now be used as base for a clinically usable design.

scholarly journals Online Adaptive Optimal Control of Vehicle Active Suspension Systems Using Single-Network Approximate Dynamic Programming

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Zhi-Jun Fu ◽  
Bin Li ◽  
Xiao-Bin Ning ◽  
Wei-Dong Xie
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Approximate Dynamic Programming ◽  
Control Method ◽  
Active Suspension ◽  
Suspension System ◽  
Lyapunov Theory ◽  
Adaptive Optimal Control ◽  
Suspension Systems ◽  
Optimal Control Method

In view of the performance requirements (e.g., ride comfort, road holding, and suspension space limitation) for vehicle suspension systems, this paper proposes an adaptive optimal control method for quarter-car active suspension system by using the approximate dynamic programming approach (ADP). Online optimal control law is obtained by using a single adaptive critic NN to approximate the solution of the Hamilton-Jacobi-Bellman (HJB) equation. Stability of the closed-loop system is proved by Lyapunov theory. Compared with the classic linear quadratic regulator (LQR) approach, the proposed ADP-based adaptive optimal control method demonstrates improved performance in the presence of parametric uncertainties (e.g., sprung mass) and unknown road displacement. Numerical simulation results of a sedan suspension system are presented to verify the effectiveness of the proposed control strategy.

A suspension system with quasi-zero stiffness characteristics and inerter nonlinear energy sink

2020 ◽  
pp. 107754632097290
Author(s):  
You-cheng Zeng ◽  
Hu Ding ◽  
Rong-Hua Du ◽  
Li-Qun Chen
Keyword(s):  
Integrated Control ◽  
Harmonic Approximation ◽  
Nonlinear Energy Sink ◽  
Suspension System ◽  
Degree Of Freedom ◽  
System Parameters ◽  
Suspension Systems ◽  
Control Scheme ◽  
Energy Sink ◽  
Nonlinear Energy

In this article, a novel vibration control scheme of suspension systems is proposed. It combines the advantages of quasi-zero stiffness isolator, nonlinear energy sink absorber, and inerter. This proposed scheme can achieve low transmissibility, low amplitude, and low additional weight and resolve the conflict between riding comfort and handling stability. Strong nonlinear vibration equations of a quarter-vehicle suspension system are established. It also presents the detailed process of high-order harmonic approximation to obtain steady-state responses. Moreover, approximate solutions are validated by a numerical method. Furthermore, based on riding comfort and handling stability, the following four suspension systems are evaluated and compared, namely, 2-degree-of-freedom quarter-vehicle model, 2-degree-of-freedom quarter-vehicle with quasi-zero stiffness isolator, 2-degree-of-freedom quarter-vehicle with inerter-nonlinear energy sink absorber, and 2-degree-of-freedom quarter-vehicle integrated control scheme with quasi-zero stiffness and inerter-nonlinear energy sink. It is found that the integrated control scheme with quasi-zero stiffness and inerter-nonlinear energy sink can significantly improve the riding comfort and handling stability at the same time. In addition, the effects of system parameters are studied carefully. The results show that based on the reasonable design of the control system parameters, better riding comfort and handling stability can be obtained. In short, this article provides a theoretical basis for integrating quasi-zero stiffness isolators and inerter-nonlinear energy sink absorbers to improve the riding comfort and handling stability.

A research of sliding mode control method with disturbance observer combining skyhook model for active suspension systems

2019 ◽  
Vol 26 (11-12) ◽  
pp. 952-964 ◽  
Author(s):  
Wu Qin ◽  
Wen-Bin Shangguan ◽  
Kegang Zhao
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Active Suspension ◽  
Suspension System ◽  
Suspension Systems ◽  
Mode Control ◽  
Active Suspension Systems ◽  
Mass Displacement ◽  
The Impact

Based on a nonlinear two-degree-of-freedom model of active suspension systems, an approach of the sliding mode control with disturbance observer combining skyhook model sliding mode control with disturbance observer combining is proposed for improving the performance of active suspension systems, and the effectiveness of the proposed approach is validated by the active suspension system plant. Two problems of active suspension systems are solved by using the proposed approach when the tire is excited by the step displacement. One problem is that the suspension deflection of active suspension systems, i.e. the difference between the sprung mass displacement and the unsprung mass displacement, using conventional sliding mode control with disturbance observer not converges to zero in finite time, and the phenomenon of the impact of suspension against the limit block is produced. This problem is solved by providing a reference value of the sprung mass displacement in an active suspension system, which is obtained from the skyhook model. The other problem is that disturbances exist in active suspension systems, which are caused by the inaccurate parameters of stiffness and damping. This problem is solved by designing a disturbance observer to estimate the summation of the disturbances. Finally, the performance indexes of the active suspension system with the sliding mode control with disturbance observer combining skyhook model are calculated and compared with those of using the conventional sliding mode control with disturbance observer and the linear quadratic regulator approach.

Disaggregated Space System Concept Optimization: Model-Based Conceptual Design Methods

2015 ◽  
Vol 18 (6) ◽  
pp. 549-567 ◽  
Author(s):  
Robert E. Thompson ◽  
John M. Colombi ◽  
Jonathan Black ◽  
Bradley J. Ayres
Keyword(s):  
Conceptual Design ◽  
Optimization Model ◽  
Design Methods ◽  
Space System ◽  
Model Based ◽  
System Concept

Control Bifurcations in a Nonlinear Active Suspension System for System Design

2005 ◽  
Author(s):  
Amit Shukla ◽  
Jeong Hoi Koo
Keyword(s):  
Control System ◽  
Ride Comfort ◽  
Active Suspension ◽  
Nonlinear Damping ◽  
Suspension System ◽  
Suspension Systems ◽  
System A ◽  
Controlled Systems ◽  
Automotive Suspension ◽  
Magneto Rheological

Nonlinear active suspension systems are very popular in the automotive applications. They include nonlinear stiffness and nonlinear damping elements. One of the types of damping element is a magneto-rheological fluid based damper which is receiving increased attention in the applications to the automotive suspension systems. Latest trends in suspension systems also include electronically controlled systems which provide advanced system performance and integration with various processes to improve vehicle ride comfort, handling and stability. A control bifurcation of a nonlinear system typically occurs when its linear approximation loses stabilizability. These control bifurcations are different from the classical bifurcation where qualitative stability of the equilibrium point changes. Any nonlinear control system can also exhibit control bifurcations. In this paper, control bifurcations of the nonlinear active suspension system, modeled as a two degree of freedom system, are analyzed. It is shown that the system looses stability via Hopf bifurcation. Parametric control bifurcation analysis is conducted and results presented to highlight the significance of the design of control system for nonlinear active suspension system. A framework for the design of feedback using the parametric analysis for the control bifurcations is proposed and illustrated for the nonlinear active suspension system.

scholarly journals Effects of temperature on performance of compressible magnetorheological fluid suspension systems

2017 ◽  
Vol 29 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Michael McKee ◽  
Faramarz Gordaninejad ◽  
Xiaojie Wang
Keyword(s):  
Theoretical Model ◽  
Energy Dissipation ◽  
Bulk Modulus ◽  
Temperature Effect ◽  
Magnetorheological Fluid ◽  
Suspension System ◽  
Shear Yield Stress ◽  
Temperature Dependent ◽  
Suspension Systems ◽  
Shear Yield

The temperature effect on performance of compressible magnetorheological fluid suspension systems is studied. Magnetorheological fluid is a temperature-dependent material where its compressibility and rheological properties change with temperature. Experimental studies were conducted to explore the temperature effects on the properties of the magnetorheological fluid and the compressible magnetorheological fluid suspension systems. The temperature effect on magnetorheological fluid properties included the bulk modulus, shear yield stress, and viscosity. It was found that the shear yield stress of the magnetorheological fluid remains unchanged within the testing range while both the plastic viscosity, using the Bingham plastic model, and the bulk modulus of the magnetorheological fluid decrease as the temperature of the fluid increases. A theoretical model that incorporates the temperature-dependent properties of magnetorheological fluid was developed to predict behavior of a compressible magnetorheological fluid suspension system. An experimental study was conducted using an annular flow compressible magnetorheological fluid suspension system with varying temperatures, motion frequencies, and magnetic fields. The experimental results are used to verify the theoretical model. Moreover, the stiffness and energy dissipation of the compressible magnetorheological fluid suspension system were obtained, experimentally. The effects of the temperature on performance characteristics of the compressible magnetorheological fluid suspension system were analyzed. It was found that both the stiffness and the energy dissipation decrease with an increase in the temperature of magnetorheological fluid.

Two-Dimensional Dynamics of Tracked Ram Air Cushion Vehicles With Fixed and Variable Winglets

1979 ◽  
Vol 101 (4) ◽  
pp. 321-331
Author(s):  
L. M. Sweet ◽  
H. C. Curtiss ◽  
R. A. Luhrs
Keyword(s):  
Active Suspension ◽  
Suspension System ◽  
Ride Quality ◽  
Vertical Acceleration ◽  
Suspension Systems ◽  
Active Suspension Systems ◽  
Air Cushion ◽  
Linearized Model ◽  
The One ◽  
Air Cushion Vehicles

A linearized model of the pitch-heave dynamics of a Tracked Ram Air Cushion Vehicle is presented. This model is based on aerodynamic theory which has been verified by wind tunnel and towed model experiments. The vehicle is assumed to be equipped with two controls which can be configured to provide various suspension system characteristics. The ride quality and dynamic motions of the fixed winglet vehicle moving at 330 km/hr over a guideway described by roughness characteristics typical of highways is examined in terms of the rms values of the vertical acceleration in the foremost and rearmost seats in the passenger cabin and the gap variations at the leading and trailing edges of the vehicle. The improvement in ride quality and dynamic behavior which can be obtained by passive and active suspension systems is examined and discussed. Optimal regulator theory is employed to design the active suspension system. The predicted rms values of the vertical acceleration in the one-third octave frequency bands are compared with the vertical ISO Specifications. It is shown that marked improvements in the ride quality can be obtained with either the passive or active suspension systems.

Sign in / Sign up

Export Citation Format

Share Document