A study on trajectory planning of hydraulic robotic excavator based on movement stability

Time-jerk optimal trajectory planning of hydraulic robotic excavator

Advances in Mechanical Engineering ◽

10.1177/16878140211034611 ◽

2021 ◽

Vol 13 (7) ◽

pp. 168781402110346

Author(s):

Yunyue Zhang ◽

Zhiyi Sun ◽

Qianlai Sun ◽

Yin Wang ◽

Xiaosong Li ◽

...

Keyword(s):

Angular Velocity ◽

Trajectory Planning ◽

Optimal Trajectory ◽

High Efficiency ◽

Optimal Solution ◽

Optimal Time ◽

Target Point ◽

Robotic Excavator ◽

The Impact ◽

Optimal Trajectory Planning

Due to the fact that intelligent algorithms such as Particle Swarm Optimization (PSO) and Differential Evolution (DE) are susceptible to local optima and the efficiency of solving an optimal solution is low when solving the optimal trajectory, this paper uses the Sequential Quadratic Programming (SQP) algorithm for the optimal trajectory planning of a hydraulic robotic excavator. To achieve high efficiency and stationarity during the operation of the hydraulic robotic excavator, the trade-off between the time and jerk is considered. Cubic splines were used to interpolate in joint space, and the optimal time-jerk trajectory was obtained using the SQP with joint angular velocity, angular acceleration, and jerk as constraints. The optimal angle curves of each joint were obtained, and the optimal time-jerk trajectory planning of the excavator was realized. Experimental results show that the SQP method under the same weight is more efficient in solving the optimal solution and the optimal excavating trajectory is smoother, and each joint can reach the target point with smaller angular velocity, and acceleration change, which avoids the impact of each joint during operation and conserves working time. Finally, the excavator autonomous operation becomes more stable and efficient.

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Joint Trajectory Planning of Space Modular Reconfigurable Satellites Based on Kinematic Model

International Journal of Aerospace Engineering ◽

10.1155/2020/8872788 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Jiping An ◽

Xinhong Li ◽

Zhibin Zhang ◽

Wanxin Man ◽

Guohui Zhang

Keyword(s):

Coordinate System ◽

Trajectory Planning ◽

Coupling Effect ◽

Kinematic Model ◽

Pso Algorithm ◽

Order Polynomial ◽

Movement Stability ◽

Joint Motions ◽

Joint Trajectory Planning ◽

Joint Coordinate System

This paper investigates the application of particle swarm optimization (PSO) algorithm to plan joint trajectories of the space modular reconfigurable satellite (SMRS). SMRS changes its configuration by joint motions to complete various space missions; its movement stability is affected by joints motions because of the dynamic coupling effect in space. To improve the movement stability in reconfiguration progress, this paper establishes the optimization object equation to characterize the movement stability of SMRS in its reconfiguration process. The velocity-level and position-level kinematic models based on the proposed virtual joint coordinate system of SMRS are derived. The virtual joint coordinate system solves the problem of asymmetric joint coordinate system resulted by the asymmetric joint arrangement of SMRS. The six-order and seven-order polynomial curves are chosen to parameterize the joint trajectories and ensure the continuous position, velocity, and acceleration of joint motions. Finally, PSO algorithm is used to optimize the trajectory parameters in two cases. Consistent optimization results in terms of the six-order and seven-order polynomial in both cases prove the PSO algorithm can be effectively used for joint trajectory planning of SMRS.

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Trajectory planning of the nursing robot based on the center of gravity for aluminum alloy structure

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2021-0060 ◽

2021 ◽

Vol 60 (1) ◽

pp. 731-743

Author(s):

Libo Zhang ◽

Hanjun Gao ◽

Huichao Xu ◽

Jing Song

Keyword(s):

Trajectory Planning ◽

Inverse Kinematics ◽

Center Of Pressure ◽

Pressure Sensors ◽

Center Of Gravity ◽

Robot Arm ◽

Planning Algorithm ◽

Movement Stability ◽

The Stability ◽

The Mathematical Model

Abstract In this paper, the robot arm is manufactured to increase the structural strength and improve safety. The stability of the nursing robot in the process of carrying out the typical nursing task of holding patients was studied, and the influence of the center of gravity on the movement stability of the nursing robot was analyzed. The mathematical model of the stability of the robot is built by using the inverse kinematics solution of the robot. By studying the trajectory planning of a nursing robot under the condition of ZMP constraint, the robot can move safely and optimally along the prescribed trajectory between two working points. The simulation results show that the algorithm can significantly improve the work safety of the robot. In the experiment, four pressure sensors are used to measure the pressure of four wheels on the ground, the data are obtained and substituted into the expression of center of pressure (COP) method. The results show that the stability is in a reasonable moving area without any hidden danger, and its COP value is less than the stable qualitative boundary, which verifies the rationality and effectiveness of the optimal center of gravity stability planning algorithm.

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