Browse Topic: Rack and pinion steering

Items (162)

Extraordinary and Special Purpose Landing Gear Systems

11/11/2025

A landing gear system comprises the most compelling assembly of engineering skills. Its importance to the successful design of an aircraft can be favorably compared with that of the aircraft's wings and engines. A landing gear system consists of several different engineering disciplines, and is continually in the public eye especially with regard to safety. The primary objective of AIR4846 is to present a record of a variety of interesting gears, gear/aircraft systems and patents, and to discuss wherever possible the lessons learned, and the reasons for the design. Thus, the document is not only a historical account, but a means of recording technical knowledge for the practical benefit of future landing gear designers. Commendable efforts have been made over the years by several individuals to make such recordings, and AIR4846 will make continual reference to them. This applies to all books, papers, or specifications that have the approval of the SAE A 5 Committee. AIR4846 also accepts the premise that an essential aircraft requirement can often justify a gears' complexity and consequent weight. However, the document's purpose is not to recommend, but to provide reliable, authenticated information. Hence, the gear designer would be better equipped to adjudicate trade studies rationally, while not restricting his/her innovative skills. Each gear design feature will be associated with as many aircraft examples as possible, and every effort will be made to ensure accuracy, authenticity, and detail clarity. Section 2 of this document describes the features of landing gear which are addressed in the specific descriptions of various landing gears (Category A). Also, special types of landing gear are categorized as Category B.

A-5B Gears, Struts and Couplings CommitteeNEW

Crank-Lever Electromagnetic Damper (CLEMD) Design for Automobile Suspension System

06-13-01-00022/4/2020

An effective damper is among the most important components of the suspension system. It ensures the right amount of damping force is acting on the suspension system to provide comfort to the passengers and proper road holding to tires. Unfortunately, the energy absorbed by the dampers from the suspension system gets wasted in the form of heat. In this article, it is proposed to use innovative electromagnetic damper (EMD) with a crank-lever mechanism to recover energy from the suspension system. The goal is to develop a lightweight design of EMD that can recover a high amount of power. For the design, an off-road vehicle is used since in off-road vehicles the amount of power wasted in the suspension system is high. Three different design approaches are used, which include single-stage gearbox type, two-stage gearbox type, and three-stage gearbox type of CLEMD. Out of them, the best design, i.e. three-stage gearbox type of CLEMD is selected because of minimum weight and inertia of the components. This article is focused on the design and analysis of the three-stage gearbox type of CLEMD. On the basis of the output of numerical simulations of vehicle model, specifications for crank-lever electromagnetic damper (CLEMD) are driven and design is carried out. Also, performance analyses of CLEMD are carried out by interfacing model of CLEMD with the model of a vehicle. The advantage of CLEMD is it can act as an actuator to provide active force in an active suspension system.

Todmal, Prashant Eknath, Melzi, Stefano

Evaluation of a Robust Haptic Interface for Semi-Autonomous Vehicles

12-02-02-00075/15/2019

The advent of steer-by-wire technologies has changed the driving paradigm for drivers and vehicle autonomy. Such technologies integrate electric motors to actuate the tire-road plus human-machine interfaces. Steer-by-wire vehicles can benefit from haptic concepts through the provision of tunable force feedback, coupled with nonlinear control, to introduce lane keeping and pathway following technologies that minimize and possibly eliminate driver actions. In this article, two vehicle haptic interfaces, including a robotic grip and a joystick, both of which are accompanied by nonlinear sliding mode control, have been developed and studied on a steer-by-wire platform integrated with a virtual reality driving environment. An operator-in-the-loop evaluation that included 30 human test subjects investigated these haptic steering interfaces over a prescribed series of driving maneuvers through real-time data logging and post-test questionnaires. A conventional steering wheel with the robust sliding mode controller was used for all the driving events for comparison. Subjective and objective results from the tests demonstrate that the driver’s experience can be enhanced by up to 76.3% with a robotic grip steering input when compared to the steering wheel during extreme maneuvers. The robotic grip’s superior performance in certain vehicle maneuvers indicates its potential as an alternative haptic steering adaptation for future semi-autonomous vehicles.

Wang, Chengshi, Wang, Yue, Wagner, John R.

Aircraft Nosewheel Steering/Centering Systems

AIR1752A (Current)

4/17/2019

The intent of this AIR is twofold: (1) to present descriptive summary of aircraft nosewheel steering and centering systems, and (2) to provide a discussion of problems encountered and “lessons learned” by various airplane manufacturers and users. This document covers both military aircraft (land-based and ship-based) and commercial aircraft. It is intended that the document be continually updated as new aircraft and/or new “lessons learned” become available.

A-5B Gears, Struts and Couplings Committee NEW Name Goes Her

Use of Cellphones as Alternative Driver Inputs in Passenger Vehicles

2019-01-12394/2/2019

Automotive drive-by-wire systems have enabled greater mobility options for individuals with physical disabilities. To further expand the driving paradigm, a need exists to consider an alternative vehicle steering mechanism to meet specific needs and constraints. In this study, a cellphone steering controller was investigated using a fixed-base driving simulator. The cellphone incorporated the direction control of the vehicle through roll motion, as well as the brake and throttle functionality through pitch motion, a design that can assist disabled drivers by excluding extensive arm and leg movements. Human test subjects evaluated the cellphone with conventional vehicle control strategy through a series of roadway maneuvers. Specifically, two distinctive driving situations were studied: a) obstacle avoidance test, and b) city road traveling test. A conventional steering wheel with self-centering force feedback tuning was used for all the driving events for comparison. Based on the lane position and vehicle response data collected, the operators’ lane tracking capability during city road traveling was slightly inferior using a cellphone compared to traditional steering wheel. However, in extreme maneuvers like obstacle avoidance and sharp right turn, the lateral tracking performance of the cellphone was up to 12.07% better than that of the steering wheel. The cellphone’s superior performance during certain vehicle maneuvers indicates its potential as an alternative steering adaptation for disabled drivers.

Wang, Chengshi, Alexander, Kim, Pidgeon, Philip, Wagner, John

Kinematics and Compliance Analysis of a 3.5 Tonne Load Capacity Independent Front Suspension for LCV

2019-01-09354/2/2019

This paper deals with the development of a 3.5 tonne carrying double wishbone front suspension for a low floor LCV. It is a novelty in this class of vehicles. It has a track width of 1810 mm and it has a recirculating ball steering system. The steering mechanism has been arranged so that the steering angle could reach to 48° that is a very effective angle in that vehicle range. This results as a lower turning radius which indicates a better handling for the vehicle. The steering and the front suspension system here have been optimized in terms of comfort and handling by using DOE (design of experiments) based on sequential programming technique. In order to achieve better suspension and steering system geometry, this technique has been applied. The results have been compared with the benchmark vehicle.

Kuris, Salih, Gungor, Efe, Deniz, Ataman, Uysal, Gulsah, Aykent, Baris

Power RACe

2019-01-13453/19/2019

Ever increasing process applications inspire us to design innovative and modular manufacturing cells in compliance with modern specifications. The result is the new highly flexible Aerospace application specific robot introduced as the “POWER RACe”. This paper describes how benchmarks for flexible automated drilling and fastening are being achieved with the Power RACe technology platform.

Dillhoefer, Thorsten, Erdinc PhD, Fatih

Optimizing Steering Column Layout and UJ Phase Angle to Enhance Vehicle Dynamics Performance

2019-01-50102/5/2019

Vehicle dynamics is one of the most important vehicle attributes. It is classified into three domains, the longitudinal, vertical, and lateral dynamics. This paper focuses on optimizing the lateral vehicle dynamics which is driven by the straight ahead controllability and cornering controllability of the vehicle. One of the important parameters that dictates these sub-attributes is the steering ratio. Therefore, designing the right steering ratio is critical to meet the vehicle “specific” targets. Significant amount of work has been done by many researchers on variable steering ratio by implementing variable gear ratio (VGR) rack, active steering, and steer-by-wire systems. This paper discusses the methodology and considerations to optimize the steering ratio for a constant gear ratio rack by optimizing the steering column layout, viz., orientation and the phase angle in universal joints. A detailed analysis of steering system layout is done to optimize the steering ratio to enhance the vehicle dynamics performance. Full vehicle-level multibody dynamics (MBD) simulations are done in ADAMS® to compare the vehicle response behavior for different steering ratios in the open-loop objective tests. The Computer Aided Engineering (CAE) results show significant impact of the proposed design methodology on vehicle controllability. When the phase angle and the initial column angle are optimized for a quick on-center steering ratio, the response gains are higher, resulting in a sporty and agile feel. However, when the same vehicle is tuned for a slower on-center steering ratio, the gains are lower, resulting in a sluggish, lazy feel. This methodology can be implemented during the initial vehicle design phase to optimize vehicle performance.

Puvvula, Praneeth, Ravuri, Susheel, Dubal, Ajit, Salunkhe, Swapnil

Steering Control of the Off-Highway Vehicles

2019-26-01081/9/2019

Steering is integral system of any vehicle to achieve direction control. With driver’s inputs, as steering wheel is turned, the steering mechanism is operated to turn the road wheels to route the vehicle on desired path. This Paper studies the different steering architectures and the learning is applied to improve the off-highway vehicles’ steering control. Off-Highway vehicles have traditionally been using Hydrostatic Power Steering (HPS) mechanism with no feedback controls. This mechanism consists of inherent limitations to vehicle efficiency, reliability and control preciseness. In this paper, HPS is modeled using 1D simulation tools from the system parameters and derived equations. The results are plotted and discussed to acknowledge the merits and demerits of existing system which helped in proposing the alternate steering solution. Different steering architectures are evaluated and trade-off study performed to choose the Electro-Hydraulic Power Steering (EHPS) architecture. The mathematical equations behind the Electro-Hydraulic steering system are derived and couple of control strategies (like PID controller and state-feedback controller) are applied to minimize the error between commanded and actual road wheel angle. Non-linear system is simulated using different software and PID controller gains are tuned to achieve desired response. Linearized state space system is modeled to obtain the state-feedback control to operate electro-hydraulic steering valve. In the end, event triggered control is discussed to operate the steering system at desired threshold for potential energy saving.

Joshi, Bharat, Sukumar, Srikant, Jawale, Vinit, Patil, Ojas

Optimization Control for 4WIS Electric Vehicle Based on the Coincidence Degree of Wheel Steering Centers

10-02-03-00117/24/2018

The steering centers of four wheels for passenger car do not coincide, which may result in tire wear and the unharmoniously movement of the vehicle. In this article, an optimization control method for Four Wheel Independent Steering (4WIS) electric vehicle based on the coincidence degree of steering centers is proposed, to improve the driving performance. The nonlinear vehicle model of the four-wheel independent steering vehicle is established, and the formula of the wheel steering center is derived. The coincidence degree of wheel steering centers is defined as the evaluation index, to describe and evaluate the performance of the coordination for wheels’ movement. Meanwhile, the structure design of 4WIS system and the establishment of Direct-Current (DC) steering motor model are carried out, and the Model Predictive Control (MPC) controller for steering actuator is designed. The coincidence degree and related performance index for 4WIS vehicle steering system are performed as the optimization target for vehicles to achieve the optimal control by neural network predictive control algorithm. Simulations based on high-fidelity CarSim model show the effectiveness of the control approach.

Zheng, Hongyu, Yang, Shuo

Steering Shaft Separation with a Collision Involved Heavy Duty Steering Gear

2018-01-05244/3/2018

A crash of a medium duty truck led to a study of the failure mechanism of the truck’s steering system. The truck, after being involved in a multi-vehicle vehicle collision, was found with its steering input shaft disconnected from the steering gear. The question arose whether the steering gear failure was a result of the collision, or causative to the collision. An in-depth investigation was conducted into whether forces on the vehicle due to the collision could cause the steering shaft to separate from the steering gear. Additionally, the performance of the steering gear with the adjuster nut progressively backed off was studied to determine the feedback a driver would receive if the steering gear came progressively apart. From the results of these studies, conclusions with regard to the crash causation were reached.

Larson, Robert, Retallack, Charles, Mikhailov, Michael

Multi-Objective Optimization to Improve SUV Ride Performances Using MSC.ADAMS and Mode Frontier

2018-01-05754/3/2018

Ride is an important attribute which must be accounted in the passenger segment vehicles. Excessive H point acceleration, Steering wheel acceleration, Pitch acceleration can reduce the comfort of the driver and the passengers during high frequency and low frequency rough road events. Excessive Understeer gradient, roll gradient, roll acceleration and Sprung mass lift could affect the Vehicle driver interaction during Steady state cornering, Braking and Step steer events. The concept architecture of the vehicle plays an important role in how comfort the vehicle will be. This paper discusses how to improve SUV ride performances by keeping handling performance attributes same or better than base vehicle. Multi Objective Optimization was carried out by keeping spring, bushing and damper characteristic as the design variables to avoid new system or component development time and cost. The first step in this process is DOE (Design of Experiments method) which allows to select critical or highly influence input variables and to understand the effect of input variables on output performances. The consequent Optimization leads to select the optimum from various conflicting solutions.

Lenka, Visweswara Rao, Anthonysamy, Baskar, Londhe, Abhijit, Hatekar, Harshad

Control of Steer by Wire System for Reference Steering Wheel Torque Tracking and Return-Ability

2018-01-05664/3/2018

This paper proposes a torque tracking algorithm via steer by wire to achieve the target steering feel and proposed a modified friction model to obtain return-ability. A three dimensional reference steering wheel torque map is designed using the measurement data of the steering characteristics of the target vehicle at a transition test and a weave test. In order to track the reference steering wheel torque, a sliding mode control is used in the tracking algorithm. In addition, to achieve return-ability, the modified friction model for steer by wire is used instead of the friction model defined in the reference steering wheel torque map. The modified friction model is composed of various models according to the angular velocity. The angular velocity and the angular acceleration used in the control algorithm are estimated using a kalman filter. A motor is used as the actuators to generate the targeted steering feel and the torque angle sensor (TAS) is used to measure the steering wheel torque and the steering wheel angle. Using the computer simulations, the return-ability of the proposed controller was evaluated with the return test and the tracking performance of the proposed controller was evaluated with the weave test and transition test. By using this proposed control algorithm in steer by wire system, the steering feel close to that of a conventional motor driven steer system has been successful obtained and return-ability has been achieved.

Lee, Jaepoong, kyongsu, Yi, Kim, Kwangil, Lee, Byungrim, Lee, Dongpil, Jang, Bongchoon, Chang, Sehyun

Power RACe

2017-01-20939/19/2017

Ever increasing process applications inspire us, as suppliers of aircraft, structural-assembly, and equipment to design innovative and modular, manufacturing cells in compliance with modern specification. The result is the new highly flexible Aerospace application specific robot identified as “POWER RACe”. This paper describes how benchmarks for flexible automated drilling and fastening are being achieved with the Power RACe technology platform.

Dillhoefer, Thorsten

Quantitative Evaluation of Steering System Rattle Noise

2017-28-19527/10/2017

Today’s automotive industry in the process of better fuel efficiency and aiming less carbon foot print is trying to incorporate energy saving and hybrid technologies in their products. One of the trends which has been followed by Original Equipment Manufacturers (OEMs) is the usage of Electric Power Steering (EPS) system. This has been an effective option to target fuel saving as compared to hydraulically assisted power steering system. EPS has been already tested successfully, not only on system level but also on vehicle level for endurance and performance by OEMs as per their norms and standards. Over the decade, NVH (noise, vibration & harshness) have become one of the touch points for customer perception about vehicle quality. This leads us to a commonly perceived problem in EPS or manual type steering system i.e. rattle noise. In this paper, a methodology has been highlighted for detection, identification and measurement of steering rattle noise and hence identifying the noise source in the steering system by fundamentally correlating measured data of noise and vibration.

Sharma, Utkarsh, Wilson, Simson T., Lalasure, Santosh, Rajakumar, K.

Adaptive Network Trained Controller for Automotive Steering Systems

2017-01-96264/11/2017

Electrical Power Assist Steering (EPAS) systems are currently eliminating the traditional hydraulic steering systems in vehicles. EPAS systems are nonlinear Multi Input Multi Output (MIMO) systems with multiple objectives, including fast response to the driver torque command, good driver feel, and attenuation of load disturbance and sensor noises. Optimal control method is employed to design EPAS system controllers for improved performance and robustness. But these controllers have showed acceptable performance for certain operating conditions and undesired steering feel for high steering gain. In this work, the neural networks are used which replace the optimal controllers of EPAS systems. A Euclidean adaptive resonance theory (EART) networks is trained according to the data collected from an H∞ optimal controller. The collected data represent the controller input and output signals. The said data are normalized and clustered into categories in the EART modules. The modules are interconnected by a map field. Once the training is accomplished, the EART controller replaces the optimal controller. The proposed controller provides improved robustness and comparatively high steering feel of EPAS system by reducing the amount required for intensive calculation. The rms value of the error signal with 75 number of clusters is lower than that of 15 clusters. The proposed technique is applicable to any arrangements of EPAS namely, rack, pinion and column EPAS.

Chabaan, Rakaan, Alam, Mohammad Saad

Towards a Supermileage Autonomous Vehicle

2017-01-01143/28/2017

The project consists on the mechanical and electronic instrumentation of an existing vehicle (built at Universidad de Monterrey for the SAE Supermileage Competition) to be able to control its steering, braking and throttle systems “by wire”. Insight to the stages of turning the vehicle into an autonomous one is presented. This includes identification of the current mechanical properties, choosing adequate components and the use of a simulation to allow early work on the software involving cameras and motors to provide autonomy to the vehicle. Using software in the loop methodology mathematical models of the dynamics of the vehicle are run in Simulink and update the position and orientation of the 3D model of the vehicle in V-REP, a robot simulator.

Lozoya Santos, Jorge De-J., Tudon-Martinez, J. C.

FRAC (Frame Riveter Assembly Cell)

2016-01-20799/27/2016

The industry wide requirement of new highly flexible automated fastening systems in aircraft production has created the need for developing new fastening systems. This paper will focus on the development of the Frame Riveting Assembly Cell (FRAC) by BROETJE-Automation to meet this need. The new FRAC machine configuration is built for automated drilling and fastening of different aircraft type parts. It is highly flexible with a high speed positioning system mounted multifunction end effector. System travel is limited only by installed track length. The FRAC integrates well with conventional and reconfigurable automated fastening work holding tools.

Janssen, Alexander, Dillhoefer, Thorsten

Steering System Noise Evaluation

2016-01-18326/15/2016

Intermediate shaft assembly is used to connect steering gear to the steering wheel. The primary function of the intermediate shaft is to transfer torsional loads. There is a high probability of noise propagating through the Intermediate shaft to the driver. The current standard for measuring the noise is by performing vehicle level subjective evaluations. If improperly clamped at either of the yokes, a sudden change in the direction of the torsional load on the Intermediate shaft can generate a displeasing noise. Noise can also be generated from the constant velocity joint. Intermediate shaft noise can be measured using a microphone or can be correlated to acceleration values. The benefit of measuring the acceleration over sound pressure level is the reduction of complexity of the test environment and test set up. The nature of the noise in question requires the filtering of low frequency data. This paper presents a new test procedure that has been developed by General Motors. The test requires the steering system to be setup in the nominal vehicle position. The steering system is loaded at the inner tie rod while acceleration levels are measured at different locations. As a function of the steering system, the linear tie rod loads are converted to torsional loads on the Intermediate shaft. The torsional loads acting on the intermediate shaft provide the necessary excitation for the displeasing noise to occur.

Kamath, Ramakrishna

Anti-Creep Mechanism Enables Ultra-Precise Motor Table Positioning

TBMG-248946/1/2016

Motion control is essential for the digitization and automation of high-tech equipment, but bearings remain basic to frictionless movement. Bearing Engineers, a bearing distributor, recently changed its name to Motion Solutions (Aliso Viejo, CA) to better reflect their evolution into a custom designer of motion solutions for high-tech electromechanical systems. Developing custom solutions has lead to developing lines of proprietary products that the company manufactures in-house.

A Novel Electric-Power-Steering (EPS) Control Algorithm Development for the Reference Steering Feel Tracking

2016-01-15464/5/2016

This paper describes a reference steering feel tracking algorithm for Electric-Power-Steering (EPS) system. Development of the EPS system with intended steering feel has been time-consuming procedure, because the feedforward map-based method has been applied to the conventional EPS system. However, in this study, a three-dimensional reference steering feel surface, which is determined from current vehicle states, is proposed. In order to track the proposed reference steering feel surface, sliding mode approach is applied to second-order steering dynamics model considering a coulomb friction model. An adaptive technique is utilized for robustness against uncertainties. In order to validate the proposed EPS control algorithm, hardware-in-the-loop simulation (HILS) has been conducted with respect to a typical steering test. It is shown that the reference steering feel is realized well by the proposed EPS control algorithm.

Lee, Dongpil, Jang, Bongchoon, Yi, Kyongsu, Chang, Sehyun, Lee, Byungrim

Simulation Study on Vehicle Road Performance with Hydraulic Electromagnetic Energy-Regenerative Shock Absorber

2016-01-15504/5/2016

This paper presents a novel application of hydraulic electromagnetic energy-regenerative shock absorber (HESA) into commercial vehicle suspension system and vehicle road performance are simulated by the evaluating indexes (e.g. root-mean-square values of vertical acceleration of sprung mass, dynamic tire-ground contact force, suspension deflection and harvested power; maximum values of pitch angle and roll angle). Firstly, the configuration and working principle of HESA are introduced. Then, the damping characteristics of HESA and the seven-degrees-of-freedom vehicle dynamics were modeled respectively before deriving the dynamic characteristics of a vehicle equipped with HESA. The control current is fixed at 7A to match the similar damping effect of traditional damper on the basis of energy conversion method of nonlinear shock absorber. Compared with the vehicle equipped with conventional shock absorber under the same excitation conditions of random road and vehicle speed, vehicle dynamics response and energy-regenerative potential of HESA suspension system are analyzed. Judging with the first three main evaluating indexes, the numerical differences between HESA equipped vehicle and conventional one in the vertical acceleration of sprung mass is within 9.2%, the dynamic tire-ground contact force is within 2.2%, and the suspension deflection is within 6.1%. The handling stability of fixed current control and failure mode of HESA is comparatively analyzed. Moreover, when offering reliable damping force for vehicle suspension system, HESA could regenerate power from 41.72 to 339.88 W (RMS) with vehicle speed ranging from 30 to 70 km/h on Class B and Class C random road.

Peng, Ming, Guo, Xuexun, Zou, Junyi, Zhang, Chengcai

Effect of Tie Rod Length Variation on Bump Steer

2016-28-02012/1/2016

Steering and suspension system has to be designed properly to achieve improved handling characteristics. Improper design of steering systems will result in steering errors such as bump steer and roll steer. These steering errors results in reduced steering performance. During the design of steering system the tie rod length has to be properly selected to reduce these steering errors. The purpose of the work is to analyze the effects of tie rod length variation on bump steer. Multi body dynamic model of the selected vehicle was created using MSC ADAMS Car software. Ideal design of steering system to achieve zero bump steer was created. The tie rod length was later varied up to 10% to study the effect of varying length on bump steer. Parallel wheel travel analysis was conducted to study the tie rod length variation on bump steer. Acceleration test was conducted on a flat road having bump to analyze the effect of changing tie rod length on steering performance of the vehicle. The test results were obtained for toe, bump steer, steer force and assist angle with 5% and 10% length variations. For 5% variation, steer assist angle was lower with 0.007deg./mm bump steer. For 10% length variation, bump steer exceeded up to 0.03 deg. /mm with greater steer assist. The results with 5% variation indicated lower bump steer as well as lesser steer assist within the acceptable range. With 10% variation, bump steer and steer assist was much higher with increased steering efforts.

Kulkarni, Upendra, Gowda, Monish M. H., Venna, Hima Kiran

Zero-Gravity Mobile Robot Using ON/OFF Adhesive Pads and Inchworm Mechanism

TBMG-236621/1/2016

Inspection of the International Space Station and other manmade objects in space is difficult because of the microgravity environment. Robots are a promising approach to accomplish these inspection tasks and later repairs, but must be able to maneuver across the surfaces. Because there is no gravity, the robot is at high risk of floating away, necessitating grippers that can adhere to the surface and resist the forces and torques of inspecting and moving on the structure.

Custom System Rides the Rails at NASA Radar Range

TBMG-23098

10/1/2015

ADC USA, Inc. (Ithaca, NY) develops and supplies high-precision motion systems and instruments for large government laboratories and corporations around the world. ADC was contracted by NASA’s Langley Research Center (Hampton, VA) to design, build, and install the major components for a 40 × 40 × 40-foot indoor radar range. NASA’s goal was to refurbish and upgrade their old indoor radar range. They want to clear out what they had and replace it with newer, better-designed equipment. The goal was to put multiple targets inside the radar range without having to get a forklift to bring them in and out – not only things such as airplanes, but anything that is detected by radar.

Optimisation of Steering System Geometry of Longer FOH Commercial Vehicles

2015-01-27219/29/2015

Commercial vehicle industry is presently striving towards development of buses with enhanced passenger safety and comfort. This calls for additional components and aggregates that eventually lead to increase in the overall length and gross vehicle weight (GVW) of the bus for the same passenger capacity. Usually, steering system of longer front overhang (FOH) vehicles have multiple linkages such as bevel box arrangement or intermediate pivot arm arrangement instead of single direct draglink because of packaging and design constraints. In this work, an attempt has been made to design the steering system for one of the longer FOH bus with single direct draglink arrangement. Here, single draglink was packaged and designed with commercially available higher strength tube material. Design optimisation of steering geometry was carried such that the steering performance was atleast on par with existing performance. The MBD analysis has been carried out to compare the performance of existing and new steering system. Steering system performance parameters that were studied are steering gear demand torque, bump steer and on-center steering response. Analysis results showed that steering demand torque at the steering gear in the new design got reduced by 22% compared to existing design. Vehicles were tested for steering wheel effort and self-centering efficiency with existing and new steering system. Since, the number of steering system parts was less in the new design, there was also reduction in the cost and weight of the system.

Lomada, Balaji, Jayaganthan, R., Vijaykumar, V.

Panel Assembly Line (PAL) for High Production Rates

2015-01-24929/15/2015

Developing the most advanced wing panel assembly line for very high production rates required an innovative and integrated solution, relying on the latest technologies in the industry. Looking back at over five decades of commercial aircraft assembly, a clear and singular vision of a fully integrated solution was defined for the new panel production line. The execution was to be focused on co-developing the automation, tooling, material handling and facilities while limiting the number of parties involved. Using the latest technologies in all these areas also required a development plan, which included pre-qualification at all stages of the system development. Planning this large scale project included goals not only for the final solution but for the development and implementation stages as well. The results: Design/build philosophy reduced project time and the number of teams involved. This allowed for easier communication and extended development time well into the project. All design teams (machine, tooling, automation, controls) collocated and worked together on integration during all stages of development and implementation for the highest level of integration. Innovative integration of the tooling and the automated equipment evolved throughout project with the teams working as one group. Latest fastening technology using all electric, ball-screw squeeze riveting was developed for high-speed and robust automated fastening. Latest mobilization technology was used to make the automated fastening machines interchangeable to reduce MTTR and to enable more PPM activities offline without affecting production. More automation was also introduced for tool changing and to the material handling systems for more consistent processing and to reduce operator intervention. All systems were developed together for full integration and to enable more safety interlocks and HMI for simplified operation. A 30 month schedule for the complete large scale assembly line was maintained to support the new aircraft launch schedule. The final solution was a coherent, streamlined and efficient assembly line capable of very high aircraft production rates (Figure 1). Figure 1 PAL, automation cell, Line 4, Position 1 (L4P1)

Assadi, Michael, Dobbs, Samuel, Stewart, Brian, Hollowell, Sean, Elsholz, Joseph

Thermoplastic Racks Open Up New Motion Control Applications

TBMG-22267

6/1/2015

Rack and pinions are linear actuators that play a critical role in a wide range of linear motion control applications. While rack and pinions are commonly thought of as a timeless technology, several new developments have helped provide significant performance improvements in specific applications. One new approach, the Roller Pinion System, replaces the traditional rack and pinion with bearing-supported rollers, increasing positional accuracy, speed and durability.

Automated Floor Drilling Equipment for the 767

2014-01-22709/16/2014

A new portable floor drilling machine, the 767AFDE, has been designed with a focus on increased reach and speed, ease-of-use, and minimal weight. A 13-foot wide drilling span allows consolidation of 767 section 45 floor drilling into a single swath. A custom CNC interface simplifies machine operations and troubleshooting. Four servo-driven, air-cooled spindles allow high rate drilling through titanium and aluminum. An aluminum space frame optimized for high stiffness/weight ratio allows high speed operation while minimizing aircraft floor deflection. Bridge track tooling interfaces between the machine and the aircraft grid. A vacuum system, offline calibration plate, and transportation dolly complete the cell.

Rediger, Jason, Malcomb, Joseph, Sylvester, Craig

Steering Kickback Diminution on EHPS for Enhancing Vehicle Ride Comfort and Handling

2013-01-289311/27/2013

Electro-Hydraulic Power Steering (EHPS) system is used in modern vehicles to effect reduction in fuel consumption rate and steering effort. The mechanical linkages between the steering wheel and tire, transfers road shocks to steering wheel as high amplitude vibration. This high amplitude vibration causes the steering wheel to deviate from driver intended position. This phenomenon is called steering kickback. The initial objective is to reduce the steering kickback with minimum changes in the vehicle systems. Using check valve is one of the inexpensive and easy operational counter measures. Vehicle level tests were done to evaluate the countermeasure and it was found to have approximately 55 % reduction in kickback. Multi Body Dynamics (MBD) simulation is done using ADAMS/Car to establish the vehicle parameters involve in steering kickback. Full car model was simulated using the experimental conditions and validated. Finally from the simulation, optimized vehicle parameters are identified to reduce the steering kickback.

Sundararajan, Rajeshkumar, Natarajasundaram, Balasubramanian, Ramamoorthy, Bhavanakumar, Subramaniam, Thirumalini

An Innovative Design Concept of Four Wheel Steering Mechanism for an Automobile

2013-01-284511/27/2013

The main characteristic of vehicle moving on road is related to its response to the drivers command and to environmental factors affecting the direction of motion of vehicle. The two basic problems in handling the vehicle are control of vehicle along the desired path and stabilization of the direction of motion of vehicle against external disturbances. The vehicle with best handling characteristics is the vehicle which can always be controlled by the driver. While parking the vehicle and doing sharp turnings the vehicle with two wheel steering cannot be more significant. The two wheel steering system takes large radius of turning and requires more space to take turn. Hence four wheel steering is preferable than two wheel steering systems. A multi-function four wheel steering system could improve directional stability at high speeds, sharp turning performance at low speeds, and parking performance of a vehicle. Generally there are three types of steering systems which include front wheel, rear wheel and four wheels. The paper deals with the mechanical steering system which can perform all these operations. The paper presents a new design of steering system which involves a connector, coupler and bevel gears. In a front wheel steering, only front wheels steer, and in a rear wheel steering only rear wheels will steer to get turning. In a four wheel steering system at low speeds, the front wheels and rear wheels are out of phase for low turning radius. However at high speeds, the front and rear wheels should be in phase to increase the stability of a vehicle. The paper presents a single steering mechanism arrangement offering three modes of steering operations possible which can be selected by the driver.

Vanamala, Uma Maheshwar, koganti, Raja Rao

Implementation of Non-Contact Drives into a High-Rail, 7-Axis, AFP Motion Platform

2013-01-22889/17/2013

Traditionally, automated fiber placement (AFP) motion platforms use rack and pinion drive trains coupled through a gearbox to a rotary motor. Extensive use of non-contact linear motors on a new AFP motion platform produces a quiet, low-maintenance system without sacrificing precision. A high-rail gantry arrangement allows dynamic performance improvements to machine acceleration and speed, while lowering power consumption costs and capital expenses. The seventh axis incorporated into the machine arrangement effectively produces an effective “five sides of a cube” work envelope, permitting complex spar and panel fabrication.

Ehinger, Peter, Faubion, Guy, Hooks, Joshua, Seever, Luke

Target Cascading Optimization of the Kinematics of a Steering System Coupled to a Double Wishbone Suspension System of a Hybrid Off-Road Vehicle

2013-01-09674/8/2013

Target cascading methodology is applied to the optimization problem of the kinematics of a rack and pinion steering mechanism coupled to a double-wishbone suspension system of a hybrid off-road vehicle. This permits the partition of a complex problem into reduced order sub-problems in a hierarchical manner, leading to a more efficient design and optimization process. According to the nature of the problem, it is proposed a four level hierarchy organization. The uppermost level is the general vehicle design problem. The second level consists in various system-level design problems such as frame, powertrain and the set suspension-steering. The steering system design problem is proposed in a third hierarchical level. At the lowest level are the components design problems. The vehicle under study will work mainly under off-road condition at low speed. Hence, at the steering design problem, two main objectives are searched for optimization: steering performance according to the Ackerman criterion and the steering-suspension coupling effect. Given that these two problems are weakly coupled, it is proposed that each objective is treated as an independent geometric optimization problem, and a coordination strategy is applied in order to guarantee a final consistence of the steering general coupled problem. The proposed methodology is applied to a design scenario and an optimal design solution is found. By this methodology, a complex kinematic problem is decomposed into simpler reduced order sub-problems. This decomposition leads to a more straightforward decision making and optimization in the design process.

Blanco, Juan, Munoz, Luis

New Light Truck Platform Chassis

2013-01-03704/8/2013

The objectives of a new generation of light trucks required the development of a new platform chassis, using advances in packaging, manufacturing efficiency, mass reduction, fuel efficiency, noise and vibration toughness, and ride comfort, while maintaining the vehicle's fun-to-drive character. This paper outlines the chassis component and packaging integration, light weight material application with structural optimization, as well as technical concepts executed to improve performance. Key component focus points are axles and bearings, wheels, tires, suspensions, brakes, engine cradles and sub-frames, steering systems, mechanical controls, and fuel and exhaust systems.

Johnson, Joshua C.

Research on the Rig Tests for Evaluation of Steering Response of Electric Power Steering(EPS) Sub-System

2012-01-19209/24/2012

EPS has now become a compelling technology that nowadays rapidly replacing hydraulic power steering in world market because of its fuel efficiency, sophisticated assist control, additional safety and convenience features. There are various types of EPS such as Column assist type, Pinion assist type and Rack assist type. Small cars with less rack force are equipped with Column or Pinion assist type EPS but for full-sized vehicles with big rack power consumption need Rack assist EPS, what we call R-EPS. Each type of EPS has merits and demerits, but from the perspective of vehicle handling performance, R-EPS has some strong points. And this is why author started this study. Subjective handling evaluation has proven the superiority of R-EPS but objective evaluation was needed. So authors have tried to compare the on center handling characteristics of each EPS on the rig tests and proposed somewhat easy and reliable test method. And by using a design of experiment (DOE) approach, this study was performed to investigate interactions between logical factors of control algorithm that influence the response of EPS.

Lee, Seongil, Roh, Eun Ho

“Motion in FEA”: An Innovative Approach for More Physical and More Accurate Vehicle Dynamics Simulation

2012-01-07624/16/2012

Vehicle dynamics is a discipline of mechanical engineering that benefited of significant improvements thanks to the progress of computational engineering. Vehicle dynamics engineers are using CAE for the development of a vehicle with MBS and FEA. The concurrent use of these two technologies is a standard in the automotive industry. However the current simulation process is not fully efficient because local geometrical and material nonlinearities are not accurately modeled in classical MBS software. This paper introduces a methodology for vehicle dynamics simulation integrating MBS capabilities in one single nonlinear FEA environment enabling an accurate modeling of nonlinearity in vehicles.

Colsoul, Frederic, Voss, Bernard, Wissart, Thomas

Research of the Impact of Power Steering System Parameters on the Vehicle Handling Stability

2012-01-02564/16/2012

The characteristic of steering system is extraordinary critical to vehicle handling and stability, and the coulomb friction, which consist of steering gear coulomb friction and kingpin coulomb friction, are usually neglected in the many previous steering system model. In the paper, the dynamic model of hydraulic power steering system (HPS) including 9 rotational degree-of-freedom (DOF) and 1 translational DOF is presented, taking into account coulomb friction of steering system, and the 2-DOF mathematical model is established based on the manipulation of dynamical theory. Then simulation of vehicle handling stability is developed using the model, a goal of investigation of effects of steering ration, stiffness coefficients and moment of inertia of parts on signs of handling and stability involving yaw rate, slip-angle of center of gravity and lateral acceleration. All the work lay good groundwork for designing and selecting of the parameters of steering system.

Liao, ShuHua, Yang, Caihong

Dynamic Research on Control Strategy of Electric Power Steering System

2012-01-02124/16/2012

The developing process of steering system has experienced four phases from the simple mechanical steering system (MS), hydraulic steering system (HPS) to electric-hydraulic steering system (EHPS), till the electric power steering system (EPS) with lower energy consumption and higher performance. EPS has been found of more and more applications in the rapid development of new energy electric vehicles. This paper aims at the dynamic research of the control strategy of EPS system. Through analyzing the simplified structure model of EPS system, the mathematical models of steering wheel-steering shaft, ECU-Assist motor and rack-pinion are established by Newton's second law. The design of curve-line assist curve is one of the main research points, especially the determination method for the function expression of all the segments in the curve-line assist curve. In order to adapt different operating conditions and reduce the side-effect of non-linear factors, three steering control modes and three compensation control methods are proposed in this paper. For verifying the effect of the control strategy proposed in this paper, the simulation model of the EPS system is built in MATLAB/Simulink®. In the simulation process, it is shown that the control strategy proposed in this paper can bring good maneuverability and stability for the EPS system and the return-to-center control and the damping compensation method can improve the dynamic performances of the EPS system.

He, Ziman, Gu, Mengyan

A Large-Scale Robotic System for Depainting Advanced Fighter Aircraft

2011-01-265210/18/2011

The general benefits of automation are well documented. Order of magnitude improvements are achievable in processing speeds, production rates, and efficiency. Other benefits include improved process consistency (inversely, reduced process variation), reduced waste and energy consumption, and risk reduction to operators. These benefits are especially true for the automation of the aerospace paint removal (or "depaint") processes. Southwest Research Institute® (SwRI®) developed and implemented two systems in the early 1990s for depainting full-body fighter aircraft at Robins Air Force Base (AFB) at Warner Robins, Georgia, and Hill AFB at Ogden, Utah. These systems have been in production use, almost continuously for approximately 20 years, for the depainting of the F-15 Eagle and the F-16 Falcon fighter aircraft, respectively. Based on these previous systems, the Advanced Fighter Aircraft Depaint System (AFADS) has been designed, built, and installed as part of a large maintenance facility for advanced fighter aircraft. The AFADS includes a number of technology enhancements, such as increasing the robot reach by an additional 10 feet to give it the capability of depainting any of the fighter aircraft in the USAF fleet. The AFADS is comprised of two identical robots (one positioned on either side of the aircraft), an aircraft positioning system, an operator control room, three levels of operator control, and an interface with the dry media depaint process. The media to be used in the process is MIL-P-85891A Type VII cornstarch-based media. Though the AFADS system represents a significant advancement in robotic depaint technology, SwRI sees other opportunities to further advance the state of the art of aircraft depaint, particularly with regards to laser processes, automation control, path programming, and the application of mobile robotic platforms. SwRI, with their collaborators, is currently developing a new laser paint removal process that was recently demonstrated on the AFADS robotic platform.

Weissling, Dan H., Wiedmann, Stephen L., Solomon, Daniel P.

AIRCRAFT NOSE WHEEL STEERING/CENTERING SYSTEMS

AIR1752 (Historical)

8/10/2011

This document covers both military aircraft (land-based and ship-based) and commercial aircraft. It is intended that the document be continually updated as new aircraft and/or new "lessons learned" become available.

A-5B Gears, Struts and Couplings Committee NEW Name Goes Her