Adaptive suspension strategy for a double wishbone suspension through camber and toe optimization

A suspension system is responsible for the safety of vehicle during its manoeuvre. It serves the dual purpose of providing stability to the vehicle while providing a comfortable ride quality to the occupants. Recent trends in suspension system have focused on improving comfort and handling of vehicles while keeping the cost, space and feasibility of manufacturing in the constraint. This paper proposes a method for improving handling characteristics of a vehicle by controlling camber and toe angle using variable length arms in an adaptive manner. In order to study the effect of dynamic characteristics of the suspension system, a simulation study has been done in this work. A quarter car physical model with double wishbone suspension geometry is modelled in SolidWorks. It is then imported and simulated using SimMechanics platform in MATLAB. The output characteristics of the passive system (without variable length arms) were validated on MSC ADAMS software. The adaptive system intends to improve vehicle handling characteristics by controlling the camber and toe angles. This is accomplished by two telescopic arms with an actuator which changes the camber and toe angle of the wheel dynamically to deliver best possible traction and manoeuvrability. Two PID controllers are employed to trigger the actuators based on the camber and toe angle from the sensors for reducing the error existing between the actual and desired value. The arms are driven by actuators in a closed loop feedback manner with help of a separate control system. Comparison between active and passive systems is carried out by analysing graphs of various parameters obtained from MATLAB simulation. From the results, it is observed that there is a reduction of 58% in the camber and 96% in toe gain. Hence, the system provides the scope of considerable adaptive strategy in controlling dynamic characteristics of the suspension system

Using Modelling and Simulation to Predict Dynamics of Converted Ground Vehicle

In order to redesign and convert the passenger ground vehicle Land Rover defender 110 into military vehicle for different surveillance and reconnaissance missions it is necessary, prior to equipment integration, to assess its future dynamic response. For this purpose, the 19-degree of freedom multibody simulation model of the defender was developed using the software package MSC.ADAMS/Car. The simulation model was validated using the instrumented experimental vehicle for two scenarios namely bump test and double lane change manoeuver. Comparison of numerical predictions suggests reasonably good agreement with the actual vehicle responses. The validated model was then used to assess the effect of longitudinal and vertical position of the added equipment on the responses of the upgraded vehicle. Lateral stability degradation due to the added equipment was also investigated defining the rollover threshold as an objective assessment criterion. The obtained results show considerable lateral stability degradation for both marching and operating heights of the added equipment

Feasibility Study of an Innovative Urban Electric-Hybrid Microcar

This paper presents the feasibility study of a new platform for electric-hybrid quadricycles, developed by addressing important concepts like passive safety and comfort, which often represent a shortcoming in this vehicle category. Starting from packaging of energy storage system and macroscopic subsystems as the main technological constraint, the study has been entirely developed in a virtual environment, with finite element verifications on preliminary models, and a subsequent cooperation phase between computer aided design and finite element analysis softwares, with a guideline for the main tests being that each could feasibly be carried out on a complete vehicle model in order to validate the original assumptions. The resulting design, with a body curb mass of less than 100 kg, was capable of integrating optimal static stiffness characteristics and crash performance, together with improved vehicle dynamics thanks to an innovative suspension archetype

Determination of the effect of tire stiffness on wheel accelerations by the forced vibration test method

The paper presents results of a vibroacoustic signal analysis of the unsprung mass in a car actuated by harmonic kinematic vibrations. A passenger car with a hydropneumatic suspension system and standard tires was examined. Different tire pressures were used during the experiments. The authors applied the short time Fourier transform method with superposition of the Hanning windows combined with the zero complement method. With reference to the STFT spectrum, values of the unsprung mass resonance frequency were identified. The results of the experiments described in the publication are particularly useful for the personnel of vehicle service stations, especially that they relate to the effect of tire pressure changes occurring in a vehicle with a hydropneumatic suspension system on the vibration test results

Dynamic Modeling and Parameter Identification of a Plug-in Hybrid Electric Vehicle

In recent times, mechanical systems in an automobile are largely controlled by embedded systems, called micro-controllers. These automobiles, installed with micro-controllers, run complex embedded code to improve the efficiency and performance of the targeted mechanical systems. Developing and testing these control algorithms using the concept of model based design (MBD) is a cost-efficient and time-saving approach. MBD employs vehicle system models throughout the design process and offers superior understanding of the system behaviour than a traditional hardware prototype based testing. Consequently, accurate system identification constitutes an important aspect in MBD. The main focus of this thesis is to develop a validated vehicle dynamics model of a Toyota Prius Plug-in hybrid vehicle. This model plays a crucial role in achieving better fuel economy by assisting in the development process of various controller designs such as energy management system, co-operative adaptive cruise control system, and trip planning module. In this work, initially a longitudinal vehicle dynamics model was developed in MapleSim that utilizes acausal modeling techniques and symbolic code generation to create models that are capable of real-time simulation. Here, the motion in longitudinal direction was given importance as it is the crucial degree of freedom (DOF) for determining the fuel consumption. Besides, the generic and full-fledged vehicle dynamics model in Simulink-based Automotive Simulation Models (ASM) software was also modified to create a validated model of the Prius. This software specifically facilitates the implementation of the model for virtual data collection using a driving simulator. Both vehicle models were verified by studying their simulation results at every stage of the development process. Once the vehicle models were fully functional, the accurate and reliable parameters that control the vehicle motion were estimated. For this purpose, experimental data was acquired from the on-road and rolling dynamometer testing of the Prius. During these tests, the vehicle was instrumented with a vehicle measurement system (VMS), global-positioning system (GPS), and inertial measurement unit (IMU) to collect synchronized vehicle dynamics data. Parameters were identified by choosing a local optimization algorithm that minimizes the difference between simulated and experimental results. Homotopy, a global optimization technique was also investigated to check the influence of optimization algorithms on the suspension parameters. This method of parameter estimation from on-road data is highly flexible and economical. Comparison with the parameters obtained from 4-Post testing, a standardized test method, shows that the proposed methods can estimate parameters with an accuracy of 90%. Moreover, the longitudinal and lateral dynamics exhibited by the developed vehicle models are in accordance with the experimental data from on-road testing. The full vehicle simulations suggest that these validated models can be successfully used to evaluate the performance of controllers in real time

Design and Analysis of Suspension System for a Formula SAE Race Car

The objective of this project is to further optimize the suspension system of a Formula SAE race car with steering system included. The suspension system is designed based on unequal length double wishbone suspension system. Several changes had beenmade for the new car with the usage of hybrid composite-spaced frame chassis and single cylinder engine. Thus, new design concepts has been introduced to suit the changes made for the vehicle which include the changes in mounting points, weight distribution, suspension kinematics plane,and steering geometry. The scope of study consists of modeling the suspension and steering components by using computeraided softwaresuch as CATIA. In addition, the Finite ElementAnalysis (FEA) is performed by using CATIA which could give instantaneous yet accurate results. Dynamics analysis will compromise the usage ofADAMSCAR software which can simulate the whole suspension and steering system behavior according to the track layout which will make better understanding regarding the study. Although the fabrications of the actual product will not being carried out, the fabrication method will be inserted together in this study as reference for future planning. Based on the designing and analysis performed, the calculated roll center height and static camber angle ofthe vehicle at the static position is -68mm from the ground and - 0.5 degree respectively. In addition, the maximum lateral load transfer being transferred during cornering with radius of7.5 meters is 91.82 N. The dynamics analysis performed in ADAMSCARS shows remarkable results in open loop step steer simulation. These results provide better understanding of the vehicle performance during the autocross events

Modelling and Navigation of Autonomous Vehicles on Roundabouts

A path following controller was proposed that allows autonomous vehicles to safely navigate roundabouts. The controller consisted of a vector field algorithm that generated velocity commands to direct a vehicle. These velocity commands were fulfilled by an actuator controller that converts the velocity commands into wheel torques and steering angles that physically move a vehicle. This conversion is accomplished using an online optimization process that relies on an internal vehicle model to solve for necessary wheel torques and steering angles. To test the controller’s performance, a 16 degree of freedom vehicle dynamic model was developed with consideration for vehicle turn physics. Firstly, tire force data was gathered by performing driving maneuvers on a test track using a vehicle fitted with tire measurement equipment. The generated tire force data was used to compare various combined slip tire force models for their accuracy. The most accurate model was added to the high-fidelity vehicle model. Next, suspension kinematic data was generated using a simple testing procedure. The vehicle was equipped with the tire measurement equipment and the vehicle was raised a lowered with a hydraulic jack. Using displacement and orientation data from this test, a novel reduced order suspension kinematic model that reproduces the observed motion profile was developed. Application of the path following controller to the high-fidelity model resulted in close following of a roundabout path with small deviations

Mechanical Components Design and Optimization for an All-Wheel-Drive Series Plug-In Hybrid Electric Vehicle

The University of Waterloo Alternative Fuels Team (UWAFT) is a student team conceived in 1996, participating in numerous student competitions which aim to reduce emissions and improve fuel economy of passenger vehicles. UWAFT was led by faculty advisors Dr. Roydon Fraser and Dr. Michael Fowler in the EcoCAR 2 competition sponsored by the Department of Energy and General Motors. The team designed and competed with a 2013 Chevrolet Malibu, which was converted to an All-Wheel-Drive Series Plug-in Hybrid Electric Vehicle. UWAFT was conceived with the primary goal of providing university students with an unparalleled level of hands-on experience through a project-based environment. Such projects build on the knowledge and skills learned in the classroom, and presents additional challenges that are not normally seen from the classroom alone. Such challenges include designing for manufacturability, sourcing components, solving problems with uncertainty, teamwork, project planning, and much more. Safety is a primary consideration with all the projects, and proper training are provided for the students, including high voltage training. One particular topic that is receiving increasing attention is knowledge retention. It is a recurring issue due to the nature of student teams, as experienced team members eventually graduate and leave the team. Although there is usually an overlap of experienced and new team members, sometimes there is a large turnover rate and knowledge retention within the team becomes a problem as a large number of experienced team members graduate and leave at once. As such, detailed documentation of lessons learned is becoming a valuable tool in team knowledge retention as well as saving experienced team members the trouble of individually teaching each and every new volunteer that joins the team. This thesis provides an outline of the general mechanical design processes as well as a focus on the mechanical design of major mechanical components that are required during a conversion of a vehicle to an Electric Vehicle (EV) or Hybrid Electric Vehicle (HEV). This thesis serves as part of the knowledge retention system for UWAFT such that new team members will have an easier time learning the design processes and understanding some of the things to look out for, with recommendations from the author based on his experiences from designing these components for UWAFT’s EcoCAR 2 vehicle