Study and Realization of a System to Reduce the Effect of the Instantaneous Rotation Center (IRC) in an Electric Vehicle

Abstract—The problem of the stability of electric vehicles is difficult during their displacements, then more and more difficult when the (EV) has a several driving wheels, and its way has a curved trajectory, this problem causes a danger for the (EV), the effect of the instantaneous center of rotation (ICR), every year many deaths in the world because of the accidents causing by this problem mentioned before. The desire to have more safety in this type of vehicle encourages us to develop driving assistance systems that help to control the (EV) on the road. Indeed, our objective of this work is to realize a system to reduce the effects of (ICR) with two wheels drive (EV) by realizing an intelligent system implemented on ardouino, and a Labview interface which used for data processing. The intelligent system controls the electric motors (DC motor), which is placed inside the wheels with other equipments allows us to visualize the speed's variations of the motors which we have already. All this is a guarantee by a new management control algorithm. Keyword Electric vehicle, ICR, Control, DC motor


II. MOVEMENT IN LACE TO A LOW-SPEED
According to the Ackermann model illustrated in Figure 1, the steering's angles of the front train are given by:

III. HIGH-SPEED IN LACE MOVEMENT
The study of a movement of the vehicle in lace at high speed amount leads us to study the rotation in lace under steady state with the hypothesis to take into account the angle of drift of the front and back train.

IV. STUDY OF DC MOTOR
It is necessary to maintain the velocity a at determined values in the presence of the external or internal perturbations influencing these quantities being inherently variable. We will realize a command of a 'Proportional-Integral ' implement at a microcontroller-based system.
For this, we will begin with a description of the various components making up our system. Obtaining his mathematical model will allow us to define the different gains of our regulator.  The (.lvm) file is designed so that it facilitates parsing the reading when imported into a spreadsheet. Obtaining a sample file (.lvm) compatible to MATLAB-will be useful in the identification operation to find the mathematical model we are looking for using its "MATLAB identification toolbox". The following figure gives an overview on the interface of the LabVIEW (Fig. 8) and the MATLAB tool ( Fig. 9) [5].

IX. PROCESS IDENTIFICATION RESULTS:
When we had excited the system with a step, we obtained the following answer: U (k): input set point. Y (k): system response We note that the sampling time is Ts = 0.1 s. Fig. 10. Response of the system to a step

XI. REGULATION WITH PI
The integral corrector is generally associated with the proportional corrector, it then develops a command which can be given by the following relation: The transfer function of the corrector is then given by: XII.

CALCULATION OF THE CONTROLLER PARAMETERS:
The parameters of the regulator are defined as a function of the damping ζ and the Pulsation .

XIII. SIMULATION:
After calculating the parameters of the controller, we performed the simulation with Matlab/Simulink simulation software and obtained the following results (Fig. 12):  Fig.13 illustrates the behavior of our system after the implementation of the digital PI controller. At first, we gave a setpoint of N = 1500tr / min, we note that the output of the system follows this instruction. Then we came down to N = 500tr/min, we also notice that the output of the system follows. Finally, with N = 1000 tr/min, the same desired behavior was obtained. The PI regulator has given satisfactory results.

PRACTICAL REALIZATION
We will test our system to decrease the effect of the Instant Rotation Center "IRC" in an electric vehicle [4]. Our synoptic diagram is composed of three parts (Fig. 14):

XVI. TEST AND RESULT
After the practical realization of our project. We have to do some experimental testing.

B. Steering right:
When turning the steering wheel to the right. When turning the steering wheel to the right, the duty cycle (between 1-2) of the signal PWM given to the right engine decreases its speed and the second motor remains constant C. Left-hand steering: When turning the steering wheel to the left. When the steering wheel is turned to the left, the duty cycle (which lies between 1-0) of the PWM signal given to the left engine decreases its speed and the second motor remains constant.
We have shown signals that we have done with our interface. These tests are intended to judge our interface that we have chosen, and obtaining results in the form of graphs on the oscilloscope and on indicators displayed by the speed of the wheels in Labview.

XVII. CONCLUSION
The objective of this work is the study and realization of a system that reduces the effects of the ICR in a vehicle. We used a Labview interface to transmit the signals to the motors (the wheels) and when turning the potentiometer (steering wheel) we notice the variation of the speed of the vehicle with the conditions as we want.
This work allowed us to enrich our knowledge in several fields, especially in the field of electric vehicles and especially on their behaviors and programming in collaboration with Labview.