Suspension Kinematics Programme

Abstract

In the automotive industry, during the early design phase for the vehicle suspension system, a design iteration between the suspension kinematics performance and packaging requirements need to be performed. Hence, to increase the working efficiency, a quick and robust design tool which can carry out basic kinematics simulation is required. Comparing to the exsisted commercial software on the market in this area (eg. MSC ADAMS/CAR), this tool will only covers selected suspension type and pure kinematics simulation. Delivering the required suspension kinematics parameters with easy and friendly user interface is the main goal. This master thesis only focus on MacPherson suspension. First, it starts with finding a suitable method for the modelling of the suspension mechanism system. Different modelling methods are compared including planar modelling and spatial modelling, relative coordinates system modelling and global coordinate system modelling. Constraint equations are formulated based on the chosen modelling method. The nonlinear equation solving problem was converted into an optimization problem to solve. Slack variable method was applied here to provide more freedom to the solver. After the equation system was solved, the data was post processed then given as required output parameters. After all the mathematical process are completed, the software implementation is performed to realize all these functions in chosen software platform. First, a simple MATLAB version is completed for early verification and back-up plan, then EXCEL is chosen to be the final software platform due to its user friendly interface and widely application. All functions are achieved by EXCEL Visual Basic Application (VBA, EXCEL coding language) with EXCEL add-in Solver. A comparison between the result from EXCEL and ADAMS/CAR was made at last to validate the accuracy of the EXCEL program.