Tire-road Friction Coefficient Estimation Based On The Propulsion Of Moving Vehicle With In-wheel Motors

With the lack of oil resources，the sustainable development of FV(fuel vehicles)has become a serious challenge. At the same time，a variety of new energy vehicleshas welcomed the opportunity of rapid development. PEV (pure electric vehicle) isone of them. The great difference between the EV and the FV is the vehicle’spropulsion system that is why the pure electric vehicles is different from thetraditional fuel vehicles, while both of them have their own advantages anddisadvantages. By comparison with the FVs, the PEVs with In-Wheel motor can bedriven forward independently and the driving torque from perception to executivecontrol seems more rapid and precise. On one hand, the control of propulsion torquecan be directly and efficiently achieved through the control of the motor current. Onthe other hand, the timely and effective acquirement of the propulsion torque frommotor sensing devices can be used for more accurate and reliable estimation of thevehicle’s movement state and perception of road information. This paper is focusedon the latter and can commence in combination with past research about Tire-RoadFriction Coefficient estimation.Road-Tire Friction Coefficient is a physical quantity to reflect the roadinformation. The perception of the road conditions is essential in vehicle active safetycontrol technology. The research on estimation tire-road adhesion coefficient is veryextensive, but intact、uniform、effective theoretical methods and practical experiencehas not been built，which is decided by lots of complex factors of the coefficientestimation itself and one of them is the propulsion torque cannot be quickly andeffectively obtained. The driving torque on tire in FV needs to be acquired through theengine and powertrain system. The real judgment and control of propulsion areusually completed only through the engine throttle open to the magnitudes of theadjustment; apparently, the accuracy of torque obtained by the conversion will begreatly affected.Therefore, with the introduction of In-Wheel motor in PEV, its drive torque canbe timely and precisely got, which can improve the effectiveness and accuracy aboutTire-Road Friction Coefficient estimation, all of this becomes a huge advantage in comparison with fuel vehicles. This paper is mainly based on it, specific works asfollows1) The establishment of longitudinal vehicle dynamics model as the basis for theTire-Road friction coefficient estimation, the longitudinal tire force estimation can beachieved by the wheelspin model and selecting the appropriate tire model as areference model. By the combination of the three organic, choos ing the recursive leastsquares method as the theoretical support, the whole architecture about tire-roadfriction coefficient estimation has been established.2) According to framework above, the corresponding specific theoretical modeland algorithm structure would be erected in the simulation environment (Carsim,Matlab/Simulink), in comparison with the output of Carsim’s model, the correctnessand validity of the model takes a verification with constant validation and debugging.3) Although not to get verification on a real vehicle, what the real operatingcondition is should try to be taken into consideration in simulation environment. Thesimulated validation of tire-road friction coefficient estimation is related to the threerepresentative road conditions, they are settings of0.2,0.4and0.75, respectively inCarsim; while the moving vehicle’s propulsion conditions are different and weconsider two kinds of conditions, one corresponding road conditions of0.2, andanother corresponding to0.4and0.75.