Optimum Active Vehicle Suspensions With Actuator Time Delay

2000 ◽  
Vol 123 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Nader Jalili ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Optimal Control ◽  
Time Delay ◽  
Wide Band ◽  
Fixed Time ◽  
Realistic Model ◽  
Vertical Acceleration ◽  
Band Frequency ◽  
The Road ◽  
Stability Chart ◽  
The Stability

A new approach to optimal control of vehicle suspension systems, incorporating actuator time delay, is presented. The inclusion of time delay provides a more realistic model for the actuators, and the problem is viewed from a different perspective rather than the conventional optimal control techniques. The objective here is to select a set of feedback gains such that the maximum vertical acceleration of the sprung mass is minimized, over a wide band frequency range and when subjected to certain constraints. The constraints are dictated by the vehicle stability characteristics and the physical bounds placed on the feedback gains. Utilizing a Simple Quarter Car model, the constrained optimization is then carried out in the frequency domain with the road irregularities described as random processes. Due to the presence of the actuator time delay, the characteristic equation is found to be transcendental rather than algebraic, which makes the stability analysis relatively complex. A new scheme for the stability chart strategy with fixed time delay is introduced in order to address the stability issue. The stability characteristics are also verified utilizing other conventional methods such as the Michailov technique. Results demonstrate that the suspension system, when considering the effect of the actuator time delay, exhibits a completely different behavior.

Efficient Computation of Stability Charts for Linear Time Delay Systems

2005 ◽  
Author(s):  
Dimitri Breda ◽  
Stefano Maset ◽  
Rossana Vermiglio
Keyword(s):  
Time Delay ◽  
Linear Time ◽  
Computational Cost ◽  
Characteristic Root ◽  
Delay Systems ◽  
Time Delay Systems ◽  
Efficient Computation ◽  
Square Grid ◽  
Stability Chart ◽  
The Stability

A new efficient algorithm for the computation of the stability chart of linear time delay systems is proposed and tested on several examples. The stability chart is obtained by investigating the 2d-parameter space by a first coarse square grid which is then adaptively refined by triangulation to match the desired tolerance. This leads to a considerable reduction in computational cost with respect to investigate a uniform fine square grid. Stability of each point is determined by approximating the rightmost characteristic root real part via a numerical scheme recently developed by the authors and based on pseudospectral differencing methods. A Matlab code is included in appendix.

Nonlinear Disturbance Observer Based Impedance Control for a Teleoperation System Under Time Delay

2009 ◽  
Author(s):  
A. Monemian Esfahani ◽  
S. M. Rezaei ◽  
M. Zareinejad
Keyword(s):  
Time Delay ◽  
Disturbance Observer ◽  
Impedance Control ◽  
Fixed Time ◽  
Design Parameters ◽  
Control Input ◽  
Nonlinear Disturbance Observer ◽  
Teleoperation System ◽  
Nonlinear Disturbance ◽  
The Stability

In this paper a nonlinear disturbance observer (NDO) based impedance control is proposed for a teleoperation system. The unknown friction and uncertainties will be estimated by the observer and added to the control input for compensation. Although friction will improve the stability, it worsens the transparency of the system which is another major point in teleoperation systems. The stability of the system is guaranteed by Lyapunov stability criterion and selecting the best design parameters. Tracking of force/position is achieved by these parameters. Also a fixed time delay is added to the system because of delays in the cables and other sources, it is then compensated with the designed controller. Performance of the proposed control is validated by experimental results.

Research on Optimal Control and Simulation for Active Suspension Systems

2013 ◽  
Vol 340 ◽  
pp. 631-635
Author(s):  
Yong Fa Qin ◽  
Jie Hua ◽  
Long Wei Geng
Keyword(s):  
Optimal Control ◽  
Ride Comfort ◽  
Mathematic Model ◽  
Active Suspension ◽  
Suspension System ◽  
Vehicle Body ◽  
Vertical Acceleration ◽  
The Road ◽  
Suspension Systems ◽  
Active Suspension Systems

Vehicles with active suspension systems become more ride comfort and maneuverable stability, many types of active suspensions have been applied to passenger vehicles, but one of the shortcomings of an active susupension system is that the additional control power consumption is needed. The core issues of designing an active suspension system are to minimiaze vibration magnitute and control energy comsuption of the active suspension system. A new mathematic model for an active suspension system is established based on vehicle dynamics and modern control theory. An optimal control law is constructed through solving the Riccati equation, and then the transfer function is deduced to describe the relationship between the vetical velosity of the road roughness and the output of suspension system. Three typical parameters of vehicle ride comfort are researched, such as vertical acceleration of vehicle body, dynamic deflection of suspension system and dynamic deformation of tires. A case of a quarter vehicle model is studied by simulation to show that the proposed method of modeling and designing optimal controller are suitable to develop active suspension systems.

scholarly journals Hopf bifurcation and optimal control in a diffusive predator-prey system with time delay and prey harvesting

2012 ◽  
Vol 17 (4) ◽  
pp. 379-409 ◽  
Author(s):  
Xiaoyuan Chang ◽  
Junjie Wei
Keyword(s):  
Optimal Control ◽  
Hopf Bifurcation ◽  
Time Delay ◽  
Functional Differential Equations ◽  
Normal Form Theory ◽  
Flux Boundary Condition ◽  
Predator Prey ◽  
Prey System ◽  
Functional Differential ◽  
The Stability

In this paper, we investigated the dynamics of a diffusive delayed predator-prey system with Holling type II functional response and nozero constant prey harvesting on no-flux boundary condition. At first, we obtain the existence and the stability of the equilibria by analyzing the distribution of the roots of associated characteristic equation. Using the time delay as the bifurcation parameter and the harvesting term as the control parameter, we get the existence and the stability of Hopf bifurcation at the positive constant steady state. Applying the normal form theory and the center manifold argument for partial functional differential equations, we derive an explicit formula for determining the direction and the stability of Hopf bifurcation. Finally, an optimal control problem has been considered.

Stability of the Damped Mathieu Equation With Time Delay

2003 ◽  
Vol 125 (2) ◽  
pp. 166-171 ◽  
Author(s):  
T. Insperger ◽  
G. Ste´pa´n
Keyword(s):  
Differential Equation ◽  
Time Delay ◽  
Delay Differential Equation ◽  
Mathieu Equation ◽  
Important Class ◽  
System Parameters ◽  
Oscillatory Systems ◽  
Stability Chart ◽  
The Stability ◽  
Delay Differential

In the space of the system parameters, the stability charts are determined for the delayed and damped Mathieu equation defined as x¨t+κx˙t+δ+ε cos txt=bxt−2π. This stability chart makes the connection between the Strutt-Ince chart of the damped Mathieu equation and the Hsu-Bhatt-Vyshnegradskii chart of the autonomous second order delay-differential equation. The combined charts describe the intriguing stability properties of an important class of delayed oscillatory systems subjected to parametric excitation.

On the stability of a class of nonlinear time delay systems

1999 ◽  
Author(s):  
Dan Ivancscu ◽  
Silviu-Iulian Niculcscu ◽  
Jcan-Michcl Dion ◽  
Luc Dugard
Keyword(s):  
Time Delay ◽  
Delay Systems ◽  
Time Delay Systems ◽  
The Stability

Optimal control of switched impulsive systems with time delay

2013 ◽  
Vol 53 ◽  
pp. 291
Author(s):  
Wan Mei Tang ◽  
Kar Hung Wong
Keyword(s):  
Optimal Control ◽  
Time Delay ◽  
Impulsive Systems

scholarly journals Smartphone monitoring of in-ambulance vibration and noise

2021 ◽  
pp. 095441192098599
Author(s):  
Tom Partridge ◽  
Lorelei Gherman ◽  
David Morris ◽  
Roger Light ◽  
Andrew Leslie ◽  
...  
Keyword(s):  
Transport Systems ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Noise Levels ◽  
The Road ◽  
Neonatal Transport ◽  
Mass Data ◽  
Transport Team ◽  
Vertical Accelerations ◽  
Noise Vibration

Transferring sick premature infants between hospitals increases the risk of severe brain injury, potentially linked to the excessive exposure to noise, vibration and driving-related accelerations. One method of reducing these levels may be to travel along smoother and quieter roads at an optimal speed, however this requires mass data on the effect of roads on the environment within ambulances. An app for the Android operating system has been developed for the purpose of recording vibration, noise levels, location and speed data during ambulance journeys. Smartphone accelerometers were calibrated using sinusoidal excitation and the microphones using calibrated pink noise. Four smartphones were provided to the local neonatal transport team and mounted on their neonatal transport systems to collect data. Repeatability of app recordings was assessed by comparing 37 journeys, made during the study period, along an 8.5 km single carriageway. The smartphones were found to have an accelerometer accurate to 5% up to 55 Hz and microphone accurate to 0.8 dB up to 80 dB. Use of the app was readily adopted by the neonatal transport team, recording more than 97,000 km of journeys in 1 year. To enable comparison between journeys, the 8.5 km route was split into 10 m segments. Interquartile ranges for vehicle speed, vertical acceleration and maximum noise level were consistent across all segments (within 0.99 m . s−1, 0.13 m · s−2 and 1.4 dB, respectively). Vertical accelerations registered were representative of the road surface. Noise levels correlated with vehicle speed. Android smartphones are a viable method of accurate mass data collection for this application. We now propose to utilise this approach to reduce potential harmful exposure, from vibration and noise, by routing ambulances along the most comfortable roads.

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