scholarly journals A hierarchical approach for rigid-body dynamics model simplification of a high-speed parallel robot by considering kinematics performance

2021 ◽  
Vol 104 (4) ◽  
pp. 003685042110630
Author(s):  
Jinlu Ni ◽  
Jiangping Mei ◽  
Weizhong Hu
Keyword(s):  
Rigid Body ◽  
Trajectory Planning ◽  
High Speed ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Rigid Body Dynamics ◽  
Model Simplification ◽  
Hierarchical Approach ◽  
Dynamics Model ◽  
Body Dynamics

Considering the real-time control of a high-speed parallel robot, a concise and precise dynamics model is essential for the design of the dynamics controller. However, the complete rigid-body dynamics model of parallel robots is too complex for online calculation. Therefore, a hierarchical approach for dynamics model simplification, which considers the kinematics performance, is proposed in this paper. Firstly, considering the motion smoothness of the end-effector, trajectory planning based on the workspace discretization is carried out. Then, the effects of the trajectory parameters and acceleration types on the trajectory planning are discussed. But for the fifth-order and seventh-order B-spline acceleration types, the trajectory will generate excessive deformation after trajectory planning. Therefore, a comprehensive index that considers both the motion smoothness and trajectory deformation is proposed. Finally, the dynamics model simplification method based on the combined mass distribution coefficients is studied. Results show that the hierarchical approach can guarantee both the excellent kinematics performance of the parallel robot and the accuracy of the simplified dynamics model under different trajectory parameters and acceleration types. Meanwhile, the method proposed in the paper can be applied to the design of the dynamics controller to enhance the robot's performance.

scholarly journals Inverse rigid-body dynamic analysis for a 3UPS-PRU parallel robot

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401769319 ◽  
Author(s):  
Yongjie Zhao ◽  
Ziqiang Zhang ◽  
Gang Cheng
Keyword(s):  
Rigid Body ◽  
Parallel Robot ◽  
Rigid Body Dynamics ◽  
Rigid Body Dynamic ◽  
Body Dynamics ◽  
Moving Platform ◽  
Driving Torque ◽  
Joint Acceleration ◽  
Body Dynamic ◽  
Base Platform

Inverse rigid-body dynamic analysis for a 3UPS-PRU parallel robot are conducted in this research. The position, velocity, acceleration, jerk, and singularity are considered in the inverse kinematics analysis. The rigid-body dynamic model is developed by means of the principle of virtual work and the concept of link Jacobian matrices. The driving torque, driving power, and required output work of motors have been computed in the inverse rigid-body dynamics analysis. For the pre-defined trajectory, the required output work generated by the driving motor is achieved by numerical integration technique. The inverse kinematics and rigid-body dynamics have been investigated in an exhaustive decoupled way. The effects of the velocity of the moving platform on the components of the joint acceleration, joint jerk, driving torque, and driving power, which are related to the velocity of the moving platform, are investigated. There are linear relationships between the acceleration of the moving platform and the components of the joint acceleration, joint jerk, driving torque, and driving power, which are related to the acceleration of the moving platform. The total driving torques, the torques related to the acceleration, velocity, and gravity, the torques related to the moving platform, strut connected with the moving platform, strut connected with the base platform, and motor rotor-coupler are calculated. The total driving powers, the powers related to the acceleration component of torque, velocity component of torque, gravity component of torque, and the powers related to the moving platform, strut connected with the moving platform, strut connected with the base platform, and motor rotor-coupler are also achieved.

Kinetostatic Analysis for the Ross Yoke-Drive Stirling Engine

1996 ◽  
Author(s):  
Robert L. Williams
Keyword(s):  
Rigid Body ◽  
Stirling Engine ◽  
Rigid Body Dynamics ◽  
Kinetics Model ◽  
Simplified Model ◽  
Dynamics Model ◽  
Drive Mechanism ◽  
Significant Difference ◽  
Stirling Engines ◽  
Body Dynamics

Abstract This paper presents a complete rigid body dynamics model for the Ross yoke-drive mechanism which is used to transfer power in some Stirling engines. The kinematics model is derived, followed by the kinetics model. Results are given for a representative mechanism. The shaking force and moment results are compared with those predicted by a simplified model previously used for balancing design; a significant difference is demonstrated. In the future, the model presented in this paper will be used to design more effective balancing.

Analysis of Rifle Recoil Based on Different Methods of Support

2012 ◽  
Vol 532-533 ◽  
pp. 465-468
Author(s):  
Chang Geng Wang ◽  
Wan He Xu ◽  
Cheng Xu
Keyword(s):  
Rigid Body ◽  
Prone Position ◽  
Rigid Body Dynamics ◽  
Collision Theory ◽  
Dynamics Model ◽  
Factors Influencing ◽  
Body Dynamics ◽  
Calculated Analysis ◽  
Analysis And Study

In order to analysis and study the factors influencing of measuring the rifle recoil, consider the different methods of support, based on rigid body dynamics equations and collision theory, three kinds of rifle dynamics model, which included the holder, standing and the prone position had been established. The rifle recoil curve of the different conditions had been calculated, analysis of the effects of different methods of support on the measurement of the rifle recoil.From the theoretically clarify the recoil is not a inherent properties of rifle.

Context Dependent Contact Preserving Off-Line Model Simplification for Interactive Rigid Body Dynamics Simulations

2009 ◽  
Author(s):  
Atul D. Thakur ◽  
Satyandra K. Gupta
Keyword(s):  
Rigid Body ◽  
Collision Detection ◽  
A Priori ◽  
Rigid Body Dynamics ◽  
Model Simplification ◽  
Detection Algorithms ◽  
Contact Points ◽  
Body Dynamics ◽  
Speed Up ◽  
Dynamics Simulations

Rigid body dynamics simulations require use of accurate computation of contacts among bodies. Often collision detection algorithms are used for determining the contact between moving bodies. Many mechanical parts have a large number of features and hence collision detection with the detailed part models often slows down the rigid body dynamics simulations. Model simplification techniques developed for efficient graphical rendering may change the part geometry in such a manner that the contact points between parts may change as a result of the simplification. Hence, such simplifications may alter the resulting simulated behavior. In many simulation scenarios, all the parts participating in the simulation are known in advance. In such cases, the simulation context (i.e., a priori knowledge of parts) can be exploited to simplify the part geometries such that the contact points among parts do not change. For example, parts with significant concavities may have regions on their boundaries that will be inaccessible to other parts in the simulation and hence contact points cannot lie on such inaccessible regions. Removing such regions from the parts can simplify the model and hence speed up the simulation for interactive applications.

Performance simulation and energetic analysis of TBot high-speed cable-driven parallel robot

2021 ◽  
pp. 1-14
Author(s):  
Jinhao Duan ◽  
Zhufeng Shao ◽  
Zhaokun Zhang ◽  
Fazhong Peng
Keyword(s):  
Energy Consumption ◽  
Trajectory Planning ◽  
High Speed ◽  
Low Cost ◽  
Parallel Robot ◽  
Industrial Applications ◽  
Parallel Robots ◽  
Dynamics Modeling ◽  
Serial Robots ◽  
Key Issues

Abstract Compared with serial robots, parallel robots have the advantages of high stiffness and good dynamics. By replacing the rigid limbs with cables, the cable-driven parallel robot (CDPR) is greatly simplified in structure and lightweight. We designed a high-speed CDPR tensioned by the passive rod and spring, named TBot. The robot can realize the SCARA movement as the classical Delta parallel robot. Comparison analysis of TBot and Delta is carried out to reveal the natures of the CDPRs and rigid parallel robots, identify the key issues, and promote industrial applications. Based on kinematics and dynamics modeling, performances are analyzed with simulation under a typical Adept Motion trajectory. Results illustrate that TBot has advantages of low cost, low inertia, low energy consumption and adjustable workspace and has great application potential. Energy consumption of the TBot is discussed and the trajectory planning is studied with the genetic algorithm to further reduce the energy consumption, considering the influence of the passive spring. Finally, on the basis of 30% less energy consumption for the Adept Motion than Delta, extra 14.3% energy consumption is saved through the trajectory planning of TBot.

scholarly journals Tuning of a Rigid-Body Dynamics Model of a Flapping Wing Structure With Compliant Joints

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Joseph Calogero ◽  
Mary Frecker ◽  
Zohaib Hasnain ◽  
James E. Hubbard
Keyword(s):  
Rigid Body ◽  
Motion Tracking ◽  
Compliant Mechanisms ◽  
Leading Edge ◽  
Rigid Body Dynamics ◽  
Model Parameters ◽  
Computationally Efficient ◽  
Dynamics Model ◽  
Compliant Joints ◽  
Body Dynamics

A method for validating rigid-body models of compliant mechanisms under dynamic loading conditions using motion tracking cameras and genetic algorithms is presented. The compliant mechanisms are modeled using rigid-body mechanics as compliant joints (CJ): spherical joints with distributed mass and three-axis torsional spring dampers. This allows compliant mechanisms to be modeled using computationally efficient rigid-body dynamics methods, thereby allowing a model to determine the desired stiffness and location characteristics of compliant mechanisms spatially distributed into a structure. An experiment was performed to validate a previously developed numerical dynamics model with the goal of tuning unknown model parameters to match the flapping kinematics of the leading edge spar of an ornithopter with contact-aided compliant mechanisms (CCMs), compliant mechanisms that feature self-contact to produce nonlinear stiffness, inserted. A system of computer motion tracking cameras was used to record the kinematics of reflective tape and markers placed along the leading edge spar with and without CCMs inserted. A genetic algorithm was used to minimize the error between the model and experimental marker kinematics. The model was able to match the kinematics of all markers along the spars with a root-mean-square error (RMSE) of less than 2% of the half wingspan over the flapping cycle. Additionally, the model was able to capture the deflection amplitude and harmonics of the CCMs with a RMSE of less than 2 deg over the flapping cycle.

Modeling and Identification of High Speed High Accuracy Lightweight Stages with Flexible Arms

2012 ◽  
Vol 499 ◽  
pp. 247-252
Author(s):  
S.X. Fan ◽  
D.P. Fan ◽  
Z.Y. Zhang ◽  
Y.F. Lu
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
High Performance ◽  
State Space Model ◽  
Body Part ◽  
High Accuracy ◽  
Rigid Body Dynamics ◽  
Flexible Body ◽  
Rigid Body Dynamic ◽  
Body Dynamics

Light-weight structures operating at high speeds may suffer from significant vibration problems, thus degrading positioning accuracy and exhibiting large settling time. High-performance vibration and motion controllers are usually designed based on precise dynamic model. This paper addresses the problem of modeling and identification of a high speed high accuracy lightweight positioning stage with flexible arm. A simplified state space model for vibration motion control purpose is given. A separated identification method is proposed. The parameters related to rigid body part and flexible body part are identified, separately. Rigid body dynamics is firstly identified by employing unbiased Least Squares technique. Subsequently, flexible body dynamics is identified by impact test and nonlinear LS technique. The experiment results show that applying proposed identification strategy can get more precise low frequency rigid body dynamic parameters without loss the identification precision of high frequency parameters.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

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