DOCSLIB.ORG

A Pneumatic Semi-Active Control Methodology for Vibration Control of Air Spring Based Suspension Systems William Daniel Robinson Iowa State University

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Pneumatic Semi-Active Control Methodology for Vibration Control of Air Spring Based Suspension Systems William Daniel Robinson Iowa State University Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2012 A pneumatic semi-active control methodology for vibration control of air spring based suspension systems William Daniel Robinson Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Mechanical Engineering Commons Recommended Citation Robinson, William Daniel, "A pneumatic semi-active control methodology for vibration control of air spring based suspension systems" (2012). Graduate Theses and Dissertations. 12555. https://lib.dr.iastate.edu/etd/12555 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. A pneumatic semi-active control methodology for vibration control of air spring based suspension systems by William Daniel Robinson A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Mechanical Engineering Program of Study Committee: Atul G. Kelkar, Major Professor Jerald M. Vogel James E. Bernard Judy M. Vance Greg R. Luecke Brian L. Steward Iowa State University Ames, Iowa 2012 Copyright © William Daniel Robinson, 2012. All rights reserved. ii DEDICATION To my wonderful wife and life partner, Charlyn, and to our wonderful children, Bill, Greg, David, and Ann. iii TABLE OF CONTENTS DEDICATION .......................................................................................................................... ii LIST OF FIGURES ................................................................................................................. vi LIST OF TABLES ................................................................................................................... ix ABSTRACT .............................................................................................................................. x CHAPTER 1. INTRODUCTION ............................................................................................. 1 1.1 Basic Suspension Types ............................................................................................. 2 1.1.1 Passive Suspensions ............................................................................................ 2 1.1.2 Active Suspensions ............................................................................................. 4 1.1.3 Semi-active Suspension ...................................................................................... 7 1.2 Pneumatic Suspensions .............................................................................................. 9 1.2.1 Air Springs ......................................................................................................... 9 1.2.2 Air Suspensions ............................................................................................... 10 CHAPTER 2. PLANT MODEL ............................................................................................. 12 2.1 Introduction .............................................................................................................. 12 2.2 System Equations ..................................................................................................... 15 2.2.1 Nonlinear Equations.......................................................................................... 15 2.2.2 Nonlinear Simulation Equations ....................................................................... 22 2.2.3 Pressure Composition ....................................................................................... 23 2.2.4 Linearized Dynamics ........................................................................................ 25 2.3 Linear Analysis ........................................................................................................ 31 2.3.1 Boundary Conditions and System Natural Frequencies ................................... 31 iv 2.3.2 Frequency Response ......................................................................................... 38 2.4 Nonlinear Analysis ................................................................................................... 43 2.4.1 Frequency Response as a Function of Valve Opening ..................................... 43 2.4.2 Frequency Response as a Function of Amplitude............................................. 45 2.4.3 Step Response ................................................................................................... 46 2.4.4 Additional Considerations ................................................................................ 58 2.5 System Identification................................................................................................ 59 2.5.1 Static Tests ........................................................................................................ 59 2.5.2 Step Response Tests .......................................................................................... 62 CHAPTER 3. CONTROLLER DEVELOPMENT ................................................................ 74 3.1 Introduction .............................................................................................................. 74 3.1.1 Motivation for Research ................................................................................... 75 3.1.2 Approach ........................................................................................................... 76 3.2 Review of Covariance Control Fundamentals ......................................................... 77 3.2.1 Introduction ....................................................................................................... 77 3.2.2 Mathematical Preliminaries .............................................................................. 79 3.2.3 LQI Plant Model and Control Formulation ...................................................... 81 3.2.4 Disturbance Modeling ....................................................................................... 82 3.2.5 Optimal Solution ............................................................................................... 83 3.3 Semi-Active Controller Development ...................................................................... 88 3.3.1 Introduction ....................................................................................................... 88 3.3.2 Switching Logic ................................................................................................ 89 3.3.3 LQI with Semi-Active Tracking Controller ...................................................... 90 3.3.4 Modified Skyhook with Semi-Active Tracking Controller .............................. 97 v 3.3.5 Relative Position with Semi-Active Tracking Controller ................................. 99 3.3.6 Semi-active Controller Comparisons .............................................................. 101 3.3.7 General Observations on Semi-Active Control .............................................. 104 3.4 Controller Test Implementation on the Test Rig .................................................... 105 3.4.1 Introduction ..................................................................................................... 105 3.4.2 Experimental Results ...................................................................................... 105 3.4.3 Observations and Design Issues ...................................................................... 108 CHAPTER 4. CONCLUSIONS ........................................................................................... 111 4.1 Summary ................................................................................................................ 111 4.2 Primary Research Contributions ............................................................................ 114 4.3 Future Research Directions .................................................................................... 115 BIBLIOGRAPHY ................................................................................................................. 118 ACKNOWLEDGEMENTS .................................................................................................. 122 vi LIST OF FIGURES Figure 1.1 Passive system ........................................................................................................ 3 Figure 1.2 Active suspension ................................................................................................... 4 Figure 1.3 Bose active suspension ........................................................................................... 6 Figure 1.4 Bose active seat ...................................................................................................... 6 Figure 1.5 Semi-active suspension .......................................................................................... 7 Figure 1.6 Assortment of air springs........................................................................................ 9 Figure 1.7 Reversible sleeve and convoluted designs ........................................................... 10 Figure 1.8 Separate and integrated components .................................................................... 11 Figure 2.1 Open loop system schematic ...............................................................................
Load more

Recommended publications
  • Development of Active Air Suspension System for Small Agricultural Vehicles
    Big Data In Agriculture (BDA) 2(2) (2020) 41-46 Big Data In Agriculture (BDA) DOI: http://doi.org/10.26480/bda.02.2020.41.46 ISSN: 2682-7786 (Online) CODEN: BDAIDR RESEARCH ARTICLE DEVELOPMENT OF ACTIVE AIR SUSPENSION SYSTEM FOR SMALL AGRICULTURAL VEHICLES Kamran Ikrama, Yasir Niaza, Shanawar Hamida, Muhammad Usman Ghanib, Muhammad Zeeshan Manshad, Muhammad Adnan Bodlaha, Muhammad Nadeemb,f, Muhammad Mubashar Omarb, Faizan Shabira, Muhammad Mohsin Waqasa*, Hassan Arshadc, Robeel Alic, Ghulam Yasine, Shoaib Hassanc, M. Bilal Akramc a Departmennt of Agricultural Engineering, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan. Pakistan b University of Agriculture, Faisalabad, Pakistan c Department of Mechanical Engineering, IEFR, Pakistan d Department of Plant Pathology, College of Agriculture BZU, Bahadur Sub-campus Layyah, Pakistan e Department of Forestry and Range Management, BZU, Multan, Pakistan f Department of Engineering, Faculty of Agriculture, Dalhousie University, Canada *Corresponding Author Email: [email protected] This is an open access article distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited ARTICLE DETAILS ABSTRACT Article History: Air ride suspension carries the load on each axle with a pressurized air bag just as a high pressure balloon. This system provides the smoothest and most shock free ride of any of the known vehicle suspension system. Received 11 January 2020 An air suspension includes a multiple air spring assemblies that each includes a piston airbag and a primary Accepted 13 February 2020 airbag mounted over the piston airbag.
    [Show full text]
  • Multi-Axle Air Suspension System for a Vehicle
    Europaisches Patentamt European Patent Office Office europeen des brevets (g) Publication number: 0 435 587 A2 12 EUROPEAN PATENT APPLICATION @ Application number : 90314050.7 © Int CI.5 : B60G 5/00, B60G 11/27, B60G 17/052 (22) Date of filing : 20.12.90 (So) Priority : 23.12.89 GB 8929185 @ Inventor : Griffiths, Paul John 13 East Green, Sealand Manor, Sealand Deeside, Clwyd, CH5 2SG, Wales (GB) (43) Date of publication of application : 03.07.91 Bulletin 91/27 @ Representative : Spall, Christopher John et al BARKER, BRETTELL & DUNCAN 138 Hagley @ Designated Contracting States : Road BE DE DK ES FR IT NL Edgbaston Birmingham B16 9PW (GB) (71) Applicant : RUBERY OWEN-ROCKWELL LIMITED P.O. Box 10, Booth Street, Darlaston Wednesbury West Midlands WS10 8JD (GB) (3) Multi-axle air suspension system for a vehicle. @ A multi-axle air suspension system for a tipping vehicle having towards its near a rear axle (7'") and at least one other axle (7", T) forward of the rear axle, provides selective over-riding of the normal load equalising system between the axles during tipping so as to alleviate hogging bending moments on the vehicle's chassis. A selectively operable pressure reducing valve (41) is in circuit with a pressure air source, air springs (7C, 8C) of the rear axle (7"') and with first and second valves (23, 32), selectively operated by a third valve (39), which are in circuit with the air springs (7C, 8C ; 7B, 8B ; 7A, 8A) of the rear axle (7"') and the other axle(s) (7", 7). Operation of the first and second valves (23, 32) isolates the air springs (7C, 8C) of at least the rear axles (7"') from those of the other axle or axles (7", 7') and connects the pressure reducing valve (41) to the latter air springs (7B, 8B ; 7A, 8A) so as to lower the air pressure in those air springs.
    [Show full text]
  • Active Air Suspension System
    IJSRD - International Journal for Scientific Research & Development| Vol. 6, Issue 05, 2018 | ISSN (online): 2321-0613 Active Air Suspension System Suchit Naresh Moon Department of Mechanical Engineering Nagpur Institute of Technology, India Abstract— Air ride suspension carries the load on each axle with a pressurized air bag just as a high pressure balloon. This system provides the smoothest and most shock free ride of any of the known vehicle suspension system. An air suspension includes a multiple air spring assemblies that each includes a piston airbag and a primary airbag mounted over the piston airbag. The primary and piston airbags each have a variable volume that is controlled independently of the other for active suspension control. Air ride system provides some important following features: 1) The system automatically adjusts air pressure in the air bag so that the trailer always rides at the same height, whether lightly loaded or heavily loaded. 2) The higher air bag pressure associated with higher trailer loads automatically provides a stiffer suspension which is required for a smooth ride. 3) The lower air bag pressure for lightly loaded conditions automatically provides for a softer suspension, thus providing the same ride quality for all trailer loading conditions. Since each axle is independently supported by its own air bag, Fig. 1: Locating Suspension Units the air ride suspension is known as fully independent suspension system. The automatic control of the air bag II. FULLY ACTIVE SUSPENSION SYSTEM pressure is accomplished by a solid state electronic control system specifically designed and packaged for vehicle use. Active suspension system has the ability to response to the This system continuously checks the ride height of the vertical changes in the road input.
    [Show full text]
  • Cars • Chassis & Active Safety Systems Suspension Systems in Model 164
    Cars • Chassis & active safety systems Suspension systems in model 164, 221, 251 Specialist training Information module Cars • Chassis & active safety systems Suspension systems in model 164, 221, 251 Specialist training Information module r As at 12/05 This document is intended solely for use in training and is not subject to regular updating. Printed in Germany Note: © 2005 Copyright DaimlerChrysler AG The term »employees« does not imply any preference of gender and incorporated male and refers to maler Publisher: Global Training and female employees alike. This document with all its sections is protected under the laws of copyright. Its use for any purpose whatsoever requires the prior written consent of DaimlerChrysler AG. This applies in particular to its reproduction, distribution, modification, translation, recording on microfilm or storage and/or processing in electronic systems, including databases and on-line services. 1511 1724 02 - 1st Edition 12.05 42 As at 12/05 Content 11.01.2006 Title Page Suspension <> AIRmatic ..................................................................................................................................................................................................................... 1 AIRmatic W221 Signal Path / Block Diagram ..................................................................................................................................................................................... 2 AIRmatic W221 Level Stages.............................................................................................................................................................................................................
    [Show full text]
  • Active Suspension Control of Electric Vehicle with In-Wheel Motors
    University of Wollongong Research Online University of Wollongong Thesis Collection 2017+ University of Wollongong Thesis Collections 2018 Active suspension control of electric vehicle with in-wheel motors Xinxin Shao University of Wollongong Follow this and additional works at: https://ro.uow.edu.au/theses1 University of Wollongong Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorise you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: This work is copyright. Apart from any use permitted under the Copyright Act 1968, no part of this work may be reproduced by any process, nor may any other exclusive right be exercised, without the permission of the author. Copyright owners are entitled to take legal action against persons who infringe their copyright. A reproduction of material that is protected by copyright may be a copyright infringement. A court may impose penalties and award damages in relation to offences and infringements relating to copyright material. Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. Recommended Citation Shao, Xinxin, Active suspension control of electric vehicle with in-wheel motors, Doctor of Philosophy thesis, School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, 2018.
    [Show full text]
  • BRAKING PERFORMANCE of AIR SUSPENDED CONVERTER DOLLIES Mr
    Pages 319-335 BRAKING PERFORMANCE OF AIR SUSPENDED CONVERTER DOLLIES Mr. Scott McFarlane and Dr. Peter Sweatman Roaduser Research Pty Ltd ABSTRACT In 1996 the National Road Transport Committee (NRTC) released a national heavy vehicle axle Mass Limit Review (MLR). The MLR recommended an axle mass increase for axle groups suspended by road-friendly air-suspension. For an air-suspension to be classified as Road Friendly it is required to have a bounce frequency below 2.0Hz and have damping greater than 20% of critical. It is also a requirement that the suspension group achieves load sharing within 5%. Air suspended converter dollies have become popular in Australia, particularly the triaxle type. Triaxle dollies offer a productivity benefit of between 2.5 and 4.5 tonne when compared to a tandem converter dolly. There was concern that the increased mass offered to air-suspended dollies would significantly affect the performance of road trains under braking. The Roaduser Autosim Truck Engineering Dynamics (RATED) computer simulation models were used to simulate the performance of hinged and rigid drawbar tandem and triaxle dollies under braking. The results from the simulation showed that an air-suspended tandem converter dolly could pitch significantly under braking when compared to mechanically suspended dollies. Triaxle air suspended dollies were found to pitch somewhat less than the tandem air-suspended dolly and generated a lower longitudinal force in the coupling. This indicated that the triaxle dolly has better brake balance and should be encouraged by allowing the weight increase. Rigid drawbars on converter dollies reduce the amount of dolly pitch and hence have better brake balance.
    [Show full text]
  • OFFROAD Suspension Systems
    SUSPENSION SYSTEMS making everyday smoother • Increased comfort • Better driveability • More safety OFFROAD Increased comfort Driving on what are usually poor roads or off-road stretches demands a lot of the driver and the vehicle. A good air suspen- sion system minimises noise levels inside the vehicle and ensu- res a relaxing journey. Goods that are sensitive to shock are transported gently. Better driveability The constant ride height guaranteed by VB-FullAir suspension means your vehicle remains stable and responds to steering A safe and comfortable journey inputs as you expect. The dual channel control system ensures Everything under control with suspension systems from VB-Airsuspension your vehicle remains level and reduces body roll. Start the day relaxed More safety The day starts well; after loading you climb into your vehicle It’s therefore very important that your vehicle and its The (air) suspension systems from VB-Airsuspension improve in a relaxed frame of mind. suspension are in good shape. vehicle stability in crosswinds, when cornering and when What you gain: Away you go, fully loaded, and that’s when the stress levels evasive action, for example, is necessary. ✓ Constant ride height start to rise. A comfortable and properly working suspension Hidden, but effective ✓ Prevents off-centre level can make all the difference to your working day, so you’re A good suspension is hidden underneath your vehicle. You can’t ✓ Less body roll just as relaxed at the end of it as you were in the morning. see it, but it’s essential if you’re to enjoy a comfortable and safe ✓ Increased comfort journey.
    [Show full text]
  • Review on Active Suspension System
    SHS Web of Conferences 49, 02008 (2018) https://doi.org/10.1051/shsconf/20184902008 ICES 2018 Review on active suspension system 2 Aizuddin Fahmi Mohd Riduan1, Noreffendy Tamaldin , Ajat Sudrajat3, and Fauzi Ahmad4 1,2,4Centre for Advanced Research on Energy, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka Malaysia. 1,2,4Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia. 3Engineering Physics, Faculty of Science and Technology, Universitas Nasional-Jakarta JL. Sawo Manila, Pasar Minggu, Jakarta 12520, Indonesia. Abstract. For the past decade, active suspension systems had made up most of research area concerning vehicle dynamics. For this review, recent studies on automobile active suspensions systems were examined. Several vehicular suspension types were also described to compare amongst them. From published investigations by previous researchers, various automotive suspensions in terms of cost, weight, structure, reliability, ride comfortability, dynamic and handling performance were exhibited and compared. After careful examination, it was concluded that electromagnetic active suspensions should be the general direction of vehicle suspension designs due to its energy regeneration, high bandwidth, simpler structure, flexible and accurate force control, better handling performance as well as drive characteristics. Keywords: Active Suspension, Handling Performance, Dynamic Performance 1 Introduction Vehicle suspension main task
    [Show full text]
  • SUSPENSION SYSTEMS Making Everyday Smoother
    SUSPENSION SYSTEMS making everyday smoother VB-AIRSUSPENSION, THE IDEAL SOLUTION FOR ANY (SUSPENSION) PROBLEM. Product selection assistance Find the perfect solution for you! Product selection assistance I INTRODUCTION 03 TABLE OF CONTENTS 3 INTRODUCTION 5 ABOUT US 7 PRODUCT GROUPS 9 TROUBLESHOOTING WE MAKE EVERY Table 1: Which product group? 11 FULL AIR SUSPENSION JOURNEY A GOOD Table 2: Find the perfect solution for you! 13 VB-NIVOAIR ONE. 15 VB-FULLAIR 2C A good suspension system must provide both spring force and damping, so that the vehicle feels both stable and comfortable to drive. In 17 VB-FULLAIR 4C order to achieve this, each vehicle is fitted with suspension (coil spring suspension, leaf suspension or torsion bar suspension) and shock absorbers. The suspension under the vehicle ensures that passengers and/or the cargo do not feel every bump in the road surface. The 19 VB-ACTIVEAIR shock absorbers dampen the movement of the suspension; without shock absorbers, the vehicle would continue to pitch and roll. 21 SEMI AIR SUSPENSION Unfortunately, the standard suspension fitted to your vehicle often does not provide optimum comfort. If the level of comfort does not Table 3: Find the perfect solution for you! meet your expectations, it can leave you feeling dissatisfied. We offer a suitable solution for every (suspension) problem to help resolve this dissatisfaction. Our innovative air suspension systems and suspension applications help to ensure optimum ride comfort, increased 23 VB-SEMIAIR BASIC SYSTEM stability and greater safety, so that you can enjoy a safe and worry-free journey and be more satisfied with your vehicle.
    [Show full text]
  • Electronic Stability Control Systems on Heavy Vehicles
    U.S. Department Of Transportation National Highway Traffic Safety Administration PRELIMINARY REGULATORY IMPACT ANALYSIS FMVSS No. 136 Electronic Stability Control Systems On Heavy Vehicles Office of Regulatory Analysis and Evaluation National Center for Statistics and Analysis May 2012 People Saving People TABLE OF CONTENTS EXECUTIVE SUMMARY------------------------------------------------------ E-1 I. INTRODUCTION --------------------------------------------------- I-1 II. PROPOSED REQUIREMENTS ---------------------------------- II-1 A. Definition of ESC ------------------------------------------- II-3 B. Performance Requirements ---------------------------------II-4 1. Slowly Increasing Steer Maneuver ------------------- II-5 2. Sine With Dwell Maneuver ---------------------------- II-6 C. ESC Malfunction Telltale and Symbol ------------------- II-13 D. ESC Off Switch, Telltale and Symbol -------------------- II-14 III. HOW ESC WORKS ------------------------------------------------ III-1 A. ESC Systems ------------------------------------------------- III-1 B. How ESC Prevents Rollovers ------------------------------ III-1 C. How ESC Prevents Loss of Control ---------------------- III-3 IV. BENEFITS ----------------------------------------------------------- IV-1 A. Effectiveness of ESC and RSC ---------------------------- IV-3 B. Initial Target Population ------------------------------------ IV-7 C. Projected Target Population ------------------------------- IV-13 D. Benefits ------------------------------------------------------ IV-21
    [Show full text]
  • Semi-Active Suspension
    KYB TECHNICAL REVIEW No. 55 OCT. 2017 Glossary Semi-active Suspension Included in “The technical term used in Development of Externally-Mounted Shock Absorber with Adjustable Solenoid Damping Force” P. 25 ITO Naoki KYB TECHNICAL REVIEW editor 1 Semi-active Suspension Skyhook damper Cs (imaginary) Acceleration Speed Semi-active suspension is a type of automotive suspension systems that controls the damping force of the shock absorber in response to input from the continuously varying road surfaces. It is intended to approximately Cp: Damping coefcient of implement the active suspension (to be described later) passive damper with a damping force adjustable shock absorber Cs: Damping coefcient of Skyhook damper (hereinafter “SA”). Fcont: Controlling force M2: Sprung mass Semi-active suspension may be implemented by several M1: Unsprung mass types of control methodologies. A generally known typical K2: Suspension spring constant K1: Tire spring constant technology is Skyhook control. X0: Road surface variation X1: Unsprung variation Fig. 1 shows a Skyhook control model. An imaginary X2: Sprung variation damper (= Skyhook damper) hung from an aerial height with its end fi xed there is implemented by generating a Fig. 1 Skyhook control model force of the sprung (vehicle body) speed multiplied by the damping coeffi cient sC . A passive (= uncontrolled) damper 4th quadrant 1st quadrant (Cp), which is installed in parallel with the Skyhook damper (Cs), provides a force equivalent to the SOFT damping force of the damping force adjustable SA. When this damper model is given a random input from the road surface, the relationship between the required Contraction Expansion combined damping forces of the Skyhook and passive dampers, and the relative speed (piston speed) between the sprung and unsprung components (including tires) is Relative speed (m/s) shown in Fig.
    [Show full text]
  • Air Suspension Specific Information
    12/11/2019 Front Suspension • Wheel Alignment • Standard Procedure • 2011 Jeep Grand Cherokee (5.7L) - WK • MotoLogic CURB HEIGHT MEASUREMENT Report a problem with this article The wheel alignment is to be checked and all alignment adjustments made with the vehicle at its required curb height specification. Vehicle height is to be checked with the vehicle on a flat, level surface, preferably a vehicle alignment rack. The tires are to be inflated to the recommended pressure. All tires are to be the same size as standard equipment. Vehicle height is checked with the fuel tank full of fuel, and no passenger or luggage compartment load. Inspect the vehicle for bent or weak suspension components. Compare the parts tag on the suspect coil spring(s) to the parts book and the vehicle sales code, checking for a match. Once removed from the vehicle, compare the coil spring height to a correct new or known good coil spring. The heights should vary if the suspect spring is weak. Ride height is measured at each corner of the vehicle by calculating the difference between the cradle bolt and the center of the wheel or axle heights as follows: AIR SUSPENSION SPECIFIC INFORMATION NOTE: For vehicles with Air Suspension (SER), metric measurements must be used for accuracy AND when writing ride height values to the Air Suspension Control Module (ASCM) using a scan tool. NOTE: A different ride height setting is used for checking or performing an alignment. When measuring curb height, vehicles equipped with Air Suspension (SER) must be in the manually selected "Auto" position (5) of the terrain select switch (10), or the Normal Ride Height (NRH) mode if using a scan tool.
    [Show full text]