电动叉车线控转向系统建模与控制策略研究

发布时间：2018-03-15 09:52

本文选题：叉车　切入点：线控转向　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着人们环保意识的提高,电动叉车的使用越来越受到人们的重视。电动叉车负载变化较大,转向频繁,这就需要其具有良好的转向性能。线控转向系统是当今转向技术领域的研究热点和前沿技术之一,其主要特征是用电信号取代了转向盘和转向车轮之间的机械连接,因而可以自由设计转向时的角传递特性,极大地提高了叉车的转向特性。基于线控转向的四轮转向技术能够实现对前轮和后轮的转角控制,改善转向性能,因而在叉车上应用的研究变得现实而又有意义。首先介绍了线控转向技术和四轮转向技术在国内外发展现状,为了分析叉车在实际工作中的转向性能,根据立方非线性轮胎模型建立了非线性二自由度四轮转向模型,并采用横摆角速度反馈的控制方式与前轮转向及线性二自由度四轮转向做对比,结果表明非线性二自由度四轮转向模型更能反映四轮转向叉车真实转向过程。其次根据线性二自由度四轮转向模型,采用LQR算法来实现对四轮转向叉车的稳定性控制。在分析了车辆的理想状态后,设计了LQR控制器,进而实现对四轮转向叉车前、后轮的控制。通过仿真发现LQR控制能实现对理想模型较好的跟踪控制。最后在非线性二自由度四轮转向模型的基础上,采用横摆角速度与质心侧偏角联合反馈的控制策略设计模糊控制器,并考虑叉车的实际工作状况,采用空载和负载两种典型的工况进行仿真。从仿真结果中可知,联合模糊控制能够使得横摆角速度跟踪参考值,质心侧偏角的幅值明显减小,响应速度加快,较好地反映叉车在实际工况中的转向特性。
[Abstract]:With the improvement of people's environmental awareness, the use of electric forklift has attracted more and more attention. The electric forklift load changes greatly, which requires frequent steering, which has good steering performance. The steering by wire system is one of the hotspot of research and advanced technology in the field of steering, the main feature is the electrical signals to replace the steering wheel and the mechanical connection between the steering wheel, which can be free to design steering angle transfer characteristics, greatly improve the steering characteristics of forklift steering by wire. Four wheel steering technology can realize the angle of the front wheel and the rear wheel control based on improved steering performance, so the Research on the forklift applications become realistic and meaningful first. The steering by wire technology and four wheel steering technology development status at home and abroad, in order to steering performance in the actual work of the forklift according to the cubic nonlinear Tire model is established and the nonlinear two degree of freedom four wheel steering model, and the yaw angular velocity feedback control with front wheel steering and linear two degrees of freedom four wheel steering to do comparison, the results show that the nonlinear two degree of freedom four wheel steering model can reflect the real process of forklift steering wheel steering four. Secondly according to the linear two degrees of freedom four wheel steering model, using LQR algorithm to realize the steering control of forklift stability for the four round. In the analysis of the ideal state of the vehicle, a LQR controller is designed, in order to achieve the four wheel steering wheel control forklift before. By the simulation found that the LQR control can realize the ideal model for better tracking control. At last two degree of freedom nonlinear four wheel steering model based on fuzzy controller design the control strategy of yaw rate and sideslip angle feedback, and considering the actual working condition of forklift, The no-load and load of two typical conditions were simulated. From the simulation results, combined with fuzzy control can make the yaw rate tracking the reference value, the amplitude of the sideslip angle is decreased and the response speed, better reflect the characteristics of forklift steering in actual working conditions.

【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH242

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