基于有限元的轮足式悬架结构分析及优化毕业论文
2021-10-27 22:00:06
摘 要
移动机器人可用于行星探测、军事侦察、矿山开采、反恐排雷等非结构化环境中,能有效减轻人类工作强度、保护人身安全以及完成人类难以完成的工作,有着巨大的经济效益和社会效益。移动机器人可分为轮式、腿式、履带式以及轮足复合式四类。其中,轮足式机器人具备腿式机器人的高越障性能和轮式机器人的高速高效性能,被认为是下一代最有发展潜力的高性能移动机器人。但目前轮足式机器人多为关节处直接添加驱动电机来驱动轮足的运动,这种结构在足式运动状态下可以很好的进行机器人的步态运动, 但是在轮式运动状态下路面的高频冲击载荷作用于关节电机,导致关节电机受损严重大大缩减其使用寿命。现有轮足结构的载荷性能、承载性能和稳定性方面有待改进。
本文针对于目前轮足式机器人高速运动时所存在的关节电机受损严重问题,对目前的轮足结构进行了分析优化,将汽车悬架的理念应用于轮足机器人的轮足结构中,由此设计了一种轮足悬架系统。该轮足悬架系统既可以使轮足机器人实现复杂的步态运动又可以使其在高速的轮式运动中具有较好的缓冲减振能力。该轮足悬架系统主要包括臂式扭转悬架和轮足结构两部分。其中臂式扭转悬架为本文的主要设计内容,该悬架工作过程与单纵臂独立悬架类似,弹性元件采用贮能密度较高的扭杆弹簧,阻尼元件采用阻尼系数可调节的叶片式减振器。
本文主要工作内容如下:
(1)为减轻传统轮足结构的刚性冲击,提高其缓冲减震能力。将汽车悬架系统的理念应用于轮足机器人的轮足结构中,提出一种既可以主动调节轮足姿态又具有良好缓冲减震能力的轮足悬架系统。并对其整体布置,各部分的结构以及其在轮式、足式两种运动状态下的工作过程进行介绍。
(2)以某一四足机器人基本参数作为输入,对该轮足悬架系统的核心构件-“臂式扭转悬架”,进行基本性能参数的选取和计算。对其弹性元件-扭杆弹簧的刚度、尺寸以及布置方式进行设计计算,对其阻尼原件-叶片减振器进行结构和尺寸设计,建立其数学模型对振动频率和阻尼力的关系式进行推导。对其它的传动和连接部件,如调节电机、电机轴套、车架横板和车架吊耳等进行结构设计和参数计算。
(3)对该轮足悬架系统的主要受力部件,扭杆弹簧、大臂、小臂、车架横板和吊耳进行有限元分析,得到其应力和变形量云图,对其刚度和强度进行校核,对应力分布不合理的零部件进行尺寸和结构上的改进。
关键词:臂式扭转悬架;轮足机器人;轮足悬架;有限元
Abstruct
Mobile robots can be used in unstructured environments such as planetary detection, military reconnaissance, mining, anti-terrorism demining, etc., which can effectively reduce the intensity of human work, protect personal safety, and complete tasks that are difficult for humans. It has huge economic and social benefits. Mobile robots can be divided into four types: wheeled, legged, tracked, and wheel-foot combined. Among them, the wheel-foot robot has the high obstacle performance of the legged robot and the high-speed and efficient performance of the wheeled robot. It is considered to be the next generation of high-performance mobile robot with the most potential for development. However, at present, most wheel-foot robots directly add a drive motor to the joint to drive the movement of the wheel-foot. This structure can perform the gait movement of the robot well in the foot-movement state, but the road surface in the wheel-motion state. High-frequency impact load acts on the joint motor, causing serious damage to the joint motor and greatly reducing its service life. The load performance, load bearing performance and stability of the existing wheel foot structure need to be improved.
In this paper, the current wheel-foot robot has been severely damaged due to the high-speed motion of the wheel-foot robot. The current wheel-foot structure is analyzed and optimized. The concept of automobile suspension is applied to the wheel-foot structure of the wheel-foot robot. This design has a wheel-foot suspension system. The wheel-foot suspension system can not only enable the wheel-foot robot to achieve complex gait motion, but also make it have better buffering and damping capabilities in high-speed wheeled motion. The wheel-foot suspension system mainly includes an arm-type torsion suspension and a wheel-foot structure. Among them, the arm type torsional suspension is the main design content of this article. The working process of this suspension is similar to the single longitudinal arm independent suspension. The elastic element uses a torsion bar spring with a higher energy storage density. The damping element uses a blade type with adjustable damping coefficient shock absorber.
The main contents of this article are as follows:
(a)In order to reduce the rigid impact of the traditional wheel-foot structure and improve its cushioning and shock absorption capacity. Applying the concept of automobile suspension system to the wheel-foot structure of a wheel-foot robot, this paper proposes a wheel-foot suspension system that can actively adjust the attitude of the wheel-foot and has good cushioning and damping capabilities. And its overall layout, the structure of each part and its working process in the wheel and foot motion states are introduced.
(b)Taking the basic parameters of a quadruped robot as input, the core component of the wheel-foot suspension system-"arm torsion suspension" is selected and calculated for the basic performance parameters. Design and calculate the stiffness, size and arrangement of its elastic element-torsion bar spring, structure and size design of its damping element-blade damper, establish its mathematical model to derive the relationship between vibration frequency and damping force structural design and parameter calculation of other transmission and connection components such as adjustment motors, motor bushings, frame cross plates and frame lugs.
(c)The main stress components of the wheel-foot suspension system, torsion bar spring, boom, arm, frame cross plate and lifting lug were analyzed by finite element method to obtain the cloud map of stress and deformation, and the stiffness and strength were calibrated. Core, to improve the size and structure of parts with unreasonable stress distribution.
Key words: arm torsion suspension; wheel-foot robot; caster structure; finite element
目 录
第1章 绪论1
1.1 研究背景和意义1
1.2 国内外研究现状2
1.2.1 国内研究现状2
1.2.2 国外研究现状3
1.3 本文主要工作内容4
第2章 轮足悬架系统简述5
2.1 臂式扭转悬架结构和工作原理介绍5
2.2 轮足悬架系统工作过程6
2.3 本章小结7
第3章 臂式扭转型电磁主动悬架的设计8
3.1 悬架基本输入参数8
3.2 悬架性能参数的选取8
3.2.1 轮式运动状态悬架挠度的确定8
3.2.2 扭杆弹簧扭转刚度的计算9
3.2.3 轮式运动状态悬架线刚度的计算10
3.3 扭杆弹簧的设计10
3.3.1 扭杆弹簧直径和工作长度的确定11
3.3.2 扭杆弹簧端部和过渡端尺寸的确定11
3.4 叶片式减振器设计12
3.4.1 悬架相对比和阻尼系数的选取12
3.4.2 叶片式减振器结构及工作原理12
3.4.3 叶片式减振器数学模型13
3.5 调节电机及其它部件设计计算15
3.5.1 调节电机额定功率的确定15
3.5.2 电机输出轴尺寸的确定15
3.5.3 电机输出轴上平键的选择16