Vibration Prediction of the Robotic Arm Based on Elastic Joint Dynamics Modeling

Abstract

The flexibility of the joint drive system of an industrial robot can cause vibration at the end part, which can lead to motion errors. A method to predict the vibration during the motion of the robot arm is proposed considering the robot joint flexibility. The method combines the internal transfer function of the drive system and the identification of parameters under external excitation. Firstly, the dynamics of the robot joint system are modeled by a double inertia elastic system. The joint system transfer function from the electromagnetic torque to the arm vibration is obtained according to the dynamics model. To solve the unknown parameters in the transfer function, a vibration dynamics model of the joint arm under the external forces on the arm is developed. According to this model, the equivalent stiffness, damping and load inertia of the joint can be obtained by the direct parametric method. Then, the vibration spectrum of the robot arm is derived from the motor electromagnetic torque and joint dynamics models were used to predict the vibration spectrum of the robot arm. The experiments were conducted on a single-joint robot testbed, and on an articulated industrial robot. In both experiments, the key parameters in the system were determined by impact experiments. Then, the vibration signal of the arm during the robot motion was obtained by electromagnetic torque prediction. The predicted vibration signals are analyzed in comparison with the actual vibration signals. The experimental results both show the validity of the vibration prediction.

Improved Vibration Suppression Strategy of Fuzzy PI Servo Control for Dual Flexible System with Flexible Joints

“…In the field of servo system transmission, there is widely a system of two inertias connected by an elastic coupling. According to the literature [1], such joint containing nonlinear factors can be called flexible joint. The flexible joint can be equivalent to a spring structure.…”

“…The servo system of high-performance flexible manipulator usually includes flexible joints and flexible loads. The servo system with flexible characteristics can be referred to as double flexible system for short [1,2]. The flexible joint is an important part of the high performance manipulator in the double flexible system.…”

Optimizing Motion Parameters in Soft Robotic Hands Using Bayesian Optimization: Enhancing Cycle Time, Addressing Vibration, and Repeatability

“…This study develops a parameter-tuning method based on the Bayesian optimization algorithm [25]- [29], which is noted for its efficiency in parameter search among various optimization methods. As shown in Table II, various other optimization methods can achieve optimization with a small number of search trials, [17] ✘Required (assumed to be given) -Using high speed camera [14]- [16] ✘Required (obtained by sensors) Using internal sensors [13] [18] SSA-based method* [19] ✘Required (identified by searching) PSO-based method* [20] BO-based method* [21] Hardware-based method Installing additional structures or mechanisms [7]- [10] ✘Required -* PSO, SHA, BO, and SSA refer to particle swarm optimization, S. Lin's heuristic algorithm, Bayesian optimization, and sparrow search algorithm, respectively.…”

Analysis of Bifurcation Vibrations of an Industrial Robot Arm System with Joints Compliance

“…Low-frequency vibrations are related to the flexibility of the joint drive system [27]. In principle, all industrial robots have a joint stiffness that is many times lower than the stiffness of the links and exhibit significant low-frequency vibrations.…”