六轮摆臂林用底盘稳定性分析与防倾翻研究

发布时间：2018-09-11 15:07

【摘要】：伴随着国内林业总产值的逐年增长,机械化、自动化以及智能化的造林方式和采育方式必将成为今后的发展趋势,传统的林区作业底盘多为轮桥式和履带式,在崎岖不平的地形上,没有自适应调控功能,倾翻概率高。本文提出了一种改进的六轮摆臂林用底盘,可以改变底盘位姿,来提高底盘的稳定性,主要研究工作和创新点如下：1.设计了相应的虚拟样机模型并研制了试验样机,该样机由前机架、后机架、左上摆臂、右上摆臂、左人形摆臂、右人形摆臂、左后摆臂、右后摆臂,以及6个轮胎共14个活动部件组成。针对样机模型确定了该试验样机的尺寸质量参数属性和摆角范围。在前机架摆臂铰接中点处建立了底盘的基坐标系,并采用旋量理论进行底盘的运动学建模。2.采用Kane方程对该底盘进行了倾翻动力学建模,使用Fiala轮胎模型,定义了12个广义坐标,建立底盘的普遍动力学模型,通过纯倾翻条件下底盘倾翻角速度与广义速度和广义角速度的关系对底盘动力学模型进行简化,得到了最终的倾翻动力学模型。3.结合底盘的静态失稳机理、底盘运动学以及稳定锥判定方法,本文研究了摆臂角度对于底盘静态稳定性的影响,得到结论为：纵向失稳应减小摆角降低重心,侧向失稳应增大倾翻轴一侧摆角,减小对侧摆角来实现机身侧向调平,并提出了六轮摆臂底盘的静态稳定控制策略。4.结合底盘动态倾翻机理、倾翻动力学模型以及TTR预警算法,本文研究了底盘速度以及摆臂角加速度对于底盘动态失稳的影响,得到结论为：动态失稳腾空过程中加大倾翻轴的摆角加速度会减小底盘的倾翻速度,设计了相应的动态稳定控制策略,并针对单轮越障提出可一种新型主动智能越障的算法来保持机身的稳定。5.基于ADAMS与Simulink建立了联合仿真平台,分别就纵坡直行、侧坡直行以及动态碰撞三种状态进行了仿真,通过仿真对比采用相应的控制策略后,底盘的稳定性得到了不同程度的的提升。对主动智能越障进行了试验验证,被动碰撞越障下,底盘样机的最大侧倾角为4.5°,最大纵倾角为2.5°；智能越障下,底盘样机的侧倾角最大值为0.75°,最大纵倾角为0.4°,该试验验证了主动越障的算法正确性。
[Abstract]:With the increase of gross domestic product of forestry year by year, mechanization, automation and intelligent afforestation and harvesting will be the development trend in the future. The traditional forest chassis is mostly wheel-bridge type and crawler type. In the rugged terrain, there is no adaptive control function, high tipping probability. In this paper, an improved six-wheel swing arm forest chassis is proposed, which can change the position and pose of the chassis to improve the stability of the chassis. The main research work and innovation are as follows: 1. The corresponding virtual prototype model is designed and the experimental prototype is developed. The prototype consists of front frame, rear frame, left upper pendulum arm, right upper pendulum arm, left humanoid pendulum arm, right humanoid pendulum arm, left rear pendulum arm, right rear pendulum arm. And 6 tires are composed of 14 moving parts. The size and mass parameters and swing angle range of the test prototype are determined according to the prototype model. The basic coordinate system of the chassis is established at the center point of the swing arm of the front frame, and the kinematics model of the chassis is established by using the spinor theory. The Kane equation is used to establish the dynamic model of the chassis, and the Fiala tire model is used to define 12 generalized coordinates, and the universal dynamic model of the chassis is established. The dynamic model of the chassis is simplified by the relationship between the angular velocity of the chassis and the generalized velocity and the generalized angular velocity under the condition of pure tipping, and the final tipping dynamics model .3 is obtained. Combined with the static instability mechanism of the chassis, the chassis kinematics and the method of judging the stable cone, the influence of the swing arm angle on the static stability of the chassis is studied in this paper. It is concluded that the longitudinal instability should be reduced and the center of gravity should be reduced. The lateral instability should increase the side swing angle of the tilting shaft and reduce the opposite side swing angle to realize the lateral leveling of the fuselage. The static stability control strategy of the six-wheel swing arm chassis is put forward. In this paper, the influence of chassis velocity and swing arm angular acceleration on the dynamic instability of chassis is studied by combining with the dynamic tipping mechanism of chassis, the tipping dynamic model and the TTR early warning algorithm. The conclusions are as follows: increasing the angular acceleration of the tilting shaft will reduce the turning speed of the chassis during the process of dynamic destabilization and the corresponding dynamic stability control strategy is designed. A new active intelligent obstacle surmounting algorithm is proposed to maintain the stability of the fuselage. A joint simulation platform based on ADAMS and Simulink is established. The three states of vertical slope, side slope and dynamic collision are simulated, and the corresponding control strategies are adopted. The stability of the chassis is improved to varying degrees. The test results show that the maximum side inclination angle of the chassis prototype is 4.5 掳and the maximum longitudinal inclination angle is 2.5 掳under passive collision. The maximum inclination angle of the chassis prototype is 0.75 掳and the maximum longitudinal inclination angle is 0.4 掳. This experiment verifies the correctness of the algorithm of active obstacle crossing.
【学位授予单位】：北京林业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S776

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