Investigation on linear and nonlinear dynamic equation for vehicle model in numerical simulation

With the increase in vehicles in the world today, more accidents have occurred. Therefore, more safety systems are needed for conventional vehicles. However, physical testing is dangerous and costly compared with numerical simulation. So, a good numerical simulation is especially important. In general, the vehicle dynamics equations were used in the numerical simulation. There are two types of vehicle dynamics equations that are linear and nonlinear. This paper researched which one is more practical between linear and nonlinear equations in the simulations versus real-time experiments. In this paper, the equation of motion was used to simulate the state of vehicle motion during cornering conditions in the MatLab Simulink software. The results show that the value of the linear and non-linear yaw is close to the yaw from experimental at lower speed conditions. With the speed increase, the linear yaw value will decrease and farther and farther away from experimental yaw results. Although the linear equation is relatively simple to calculate, the results of the nonlinear equations are closer to the results of real experiments. In summary, the nonlinear equation is more applicable, while the linear equation is not applicable to simulate the motion of the vehicle

The effect of parallel steering of a four-wheel drive and fourwheel steer electric vehicle during spinning condition: a numerical simulation

X-by-wire technology is an advancement in automotive industry and is recognized by many countries in recent years. The in-wheel motor system is a type of drive-by-wire technology and it will be the main focused for the vehicle model in this paper. The steer-by-wire is a kind of by-wire technology in the automotive industry for the electric vehicle. [1] Steer-by-wire technology can be divided into two types which are two-wheel steering (2WS) and four-wheel steering (4WS). As we know, 2WS system is used in most of the vehicles.[2] However, the lower maneuverability will be shown in this type of vehicle during the vehicle spinning. The dynamic equation of motion was used for the simulation of vehicle movement.[3] The software of MATLAB Simulink was used to imitate that the effect of 4WD and 4WS EV during cornering.[4,5] The passive control was used in this simulation. As the result, the simulation indicated that 2WS EV is easy oversteered. After applied 4WS system, the vehicle oversteer problem was successfully solved by use parallel steering mode

An Approach to Neutral Steering of a 4WIS Vehicle with Yaw Moment Control

There are various Advanced Driver Assistance Systems (ADAS) available in the automotive industry which are developed to improve the safety of vehicles while driving. Vehicle stability system such as yaw moment control is one of ADAS that is common only on luxury vehicles with oversteer (OS) characteristics. However, the majority of vehicles in the market are designed with understeer (US) characteristics. The yaw rate of the vehicle increases gradually at low speed and can easily maneuver during cornering. The vehicle becomes uncontrollable especially for novice drivers when the yaw rate saturates at a certain level during high-speed cornering. Differential drive method as yaw moment control system has low precision as it shares the same function for the longitudinal stability control system. In this paper, we proposed four-wheel independent steering (4WIS) to improve the yaw moment of an understeer test vehicle. A steady-state cornering (SSC) simulation was performed to obtain the steering characteristic of a test vehicle. The yaw rate for the test vehicle is linearized to create a state-space linear model in the simulation. Then, SSC simulations were repeated with the 4WIS input is obtained by a PID control and the state-space as the reference value. The results show that the 4WIS system was able to improve the maneuverability of the understeer vehicle, especially at high speed by shifting the yaw rate from US to a neutral steer characteristic