摘要
为了提高农业自动化程度,拓宽农业机器人的应用范围,提高农业机器人对工作环境的适应性及工作的灵活性,该文介绍了一种六足步行机器人三自由度腿部机构。该机构由并联驱动机构和行走机构组成,既具有并联机构的特点,又具有很好的防护性。该文建立了驱动机构动平台线速度与角速度之间的关系矩阵和该腿部机构全雅可比矩阵,绘制了全雅可比矩阵条件数分布图,建立了并联驱动机构和腿部行走机构显式3×3×3形式Hessian矩阵。在满足步矩为300 mm、越障高度为200 mm的条件下,利用组合多项式的方法,对该腿部足端进行轨迹规划,并求出了足端轨迹函数。将该轨迹函数作为足端输入,分别绘制了机构驱动关节在摆动相的角速度、角加速度理论曲线和虚拟样机仿真曲线。分析曲线中的数据可得角速度、角加速度的理论与仿真结果相近度均可达到10-3 mm,从而验证了理论分析的正确性。该研究为六足机器人的开发和控制提供了参考。
In order to increase the automation level of agricultural operations, broaden the application scope of agricultural robot, and improve the ability of adapting to the different working environment and flexible work, a novel three-degree-of-freedom leg mechanism used in the six-legged walking robot is introduced. This leg mechanism comprised a drive mechanism based on 2RUS＋RU parallel manipulator and a traveling mechanism based on parallelogram mechanism. The motor of drive mechanism is fixed on body frame. This leg mechanism has not only the advantage of parallel mechanism, but also a good protectiveness. In this paper, kinematic analysis and simulation of leg mechanism of six-legged walking robot is accomplished. Firstly, based on the intrinsic relation between the angular velocity and the angular velocity of Euler angles of the dynamic platform, the relationship matrix between linear velocity and angular velocity of driving mechanism is established. Based on that, the entire Jacbian matrix in the 3×3 form of the leg mechanism is deduced by using the relationship matrix derivative method, and the explicit Hessian matrix in the 3×3×3 form of the parallel drive mechanism and the leg walking mechanism is obtained, which also adopts the method of derivative matrix. Secondly, with the rationed rotation angle of the revolute joint ranging in [-45°, 45°], a distribution diagram of condition number of the integral Jacobian matrix is drawn. The condition number of integral Jacobian matrix is changed slowly and smaller in the central region of the workspace in this diagram, so that the mechanism flexibility is good in this area and can meet the requirements of the robot movement. Lastly, under the conditions that were step increment of 300 mm and crossing obstacle height of 200 mm, the trajectory planning of the foot end is accomplished and the track function of the foot end is presented based on the method of combined polynomial, which can make the robot stable and free from impact and have a good landing performance in the process of motion. Under the condition of the geometrical parameters of the leg mechanism, the simulation model of the robot＇s leg is established and the track function of the foot end is presented when the six-legged walking robot walks straight. The function of the trajectory is as input. The velocity and acceleration curves of driver deputy based on the analytical solutions and virtual prototype are described. Through the data analysis in curves, the accuracy of angular velocity and angular acceleration based on the theory and simulation results both can reach 10^-3 mm, which indicates that the theoretic analysis is correct and feasible. In addition, the simulation results show that the maximum of angular velocity of drive joint is less than 0.33π rad/s and the maximum of angular acceleration of drive joint is less than 1.22π rad/s. Therefore, the driving speed and torque of leg mechanism are both smaller in the course of the planned trajectory movement, which is favorable to drive. Accordingly, the rationality of the trajectory planning is confirmed. The results can provide the theoretical reference for the development and control of the hexapod robot.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2016年第9期45-52,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
机械系统与振动国家重点实验室课题资助项目(MSV201506)
河北省高等学校科学技术研究项目(QN2015185)
关键词
机器人
计算机仿真
运动学
雅可比矩阵
轨迹规划
robots
computer simulation
kinematics
Jacobian matrix
trajectory planning
