电动制动助力系统摩擦补偿模型及其控制方法研究

Research on Friction Compensation Model and Control Method of Electric Brake Assist System

非线性摩擦力是影响电动制动助力(Electric brakebooster,EBB)系统位置跟踪精度的重要因素之一。针对标准Pol-Ind模型存在摩擦状态切换不连续问题,提出一种摩擦状态连续平滑过渡的近似Pol-Ind(SPol-Ind)模型。研究基于SPol-Ind模型的EBB系统的非线性摩擦特性。为抑制扰动对控制精度的影响,提出由速度补偿、惯性补偿和SPol-Ind模型摩擦补偿构成的前馈补偿控制策略,分别以正弦和三角波信号作为系统输入信号,实现EBB系统的位置跟踪和速度跟踪控制。与常规PID控制相比,前馈补偿控制下系统对正弦和三角波信号的位置跟踪误差都明显减小,速度跟踪时的上升时间也明显缩短,表明前馈补偿控制下的系统比常规PID控制具有更高的位置跟踪精度和更快的响应速度。分析基于前馈补偿控制的EBB系统的位置跟踪精度和响应能力,进行EBB系统在环(Hardware-in-the-loop,HiL)试验,试验结果表明,系统位置跟踪误差和速度上升时间的最大值约为0.18 mm和0.028 s,与仿真结果吻合,验证了前馈补偿控制下EBB系统控制策略的有效性。

Non-linear friction force is one ofthe most important factors which affects the position tracking accuracy of the electric brake booster(EBB)system.Aiming at the discontinuity of the standard Pol-Ind model in the friction state,asimilar Pol-Ind model(SPol-Ind)with continuous and smooth transition of the friction state is proposed.The nonlinear friction characteristics of the EBB system based on the SPol-Ind model are studied.In order to eliminate the influence of disturbance on control precision,a feedforward compensation control strategy including speed compensation,inertia compensation and SPol-Ind model friction compensation is put forward.Separately,take thesine signal and the triangle wave signal as the inputsof the EBB system,the position tracking and the speed tracking control are realized.Compared with conventional PID control,the position tracking errors of both sinusoidal and triangular waveform signals are significantly reduced and the rise time of speed tracking is also significantly shortened,demonstrating that the feedforward compensated control system has higher position tracking accuracy and faster response than conventional PID control.The“brake-pressure hold-un-brake”process,the position tracking accuracy,and the responsiveness of the EBB system based on feedforward compensation control are analyzed on a Hardware-in-the-loop(HiL)test rig.The experiment results are shown that the maximum values of position tracking error and speed rise time are about 0.18 mm and 0.028 s,which are consistent with the simulation results and verify the accuracy of the control strategy of the EBB system under feedforward compensation controlmethod.