A Novel Parameter Optimization Method for the Driving System of High-Speed Parallel Robots

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Xin-Jun Liu ◽  
Gang Han ◽  
Fugui Xie ◽  
Qizhi Meng ◽  
Sai Zhang

Driving system parameters optimization, especially the optimal selection of specifications of motor and gearbox, is very important for improving high-speed parallel robots' performance. A very challenging issue is parallel robots' performance evaluation that should be able to illustrate robots' performance accurately and guide driving system parameters optimization effectively. However, this issue is complicated by parallel robots' anisotropic translational and rotational dynamic performance, and the multiparameters of motors and gearboxes. In this paper, by separating the influence of translational and rotational degrees-of-freedom (DOFs) on robots' performance, a new dynamic performance index is proposed to reflect the driving torque in instantaneous acceleration. Then, the influence of driving system's multiparameters on robots' driving torque in instantaneous acceleration and cycle time in continuous motion is investigated. Based on the investigation, an inertia matching index is further derived which is more suitable for minimizing the driving torque of parallel robots with translational and rotational DOFs. A comprehensive parameterized performance atlas is finally established. Based on this atlas, the performance of a high-speed parallel robot developed in this paper can be clearly evaluated, and the optimal combination of motors and gearboxes can be quickly selected to ensure low driving torque and high pick-and-place frequency.

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Gang Han ◽  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Qizhi Meng ◽  
Sai Zhang

Abstract Parameters optimization is complicated by various parameters and nonlinear design problems. In this paper, the interaction mechanism of motion/force transmissibility and various parameters on normalized motor torque and speed of a four degrees-of-freedom (4-DOF) high-speed parallel robot is analyzed. Based on this interaction mechanism, evaluation indices of acceleration capacity, speed ability, and adept cycle time are proposed. Through combining these indices with task requirements and technical criteria of driving systems, the technology-oriented constraints are set up and a parameter optimization method is proposed. With this method, the dimensional parameters, driving system specifications, and work pose of the robot have been synchronously optimized to ensure low driving torque and high pick-and-place frequency. This synchronous optimal design method is general and can be further applied to parameter optimization for different types of parallel robots.


2010 ◽  
Vol 166-167 ◽  
pp. 457-462
Author(s):  
Dan Verdes ◽  
Radu Balan ◽  
Máthé Koppány

Parallel robots find many applications in human-systems interaction, medical robots, rehabilitation, exoskeletons, to name a few. These applications are characterized by many imperatives, with robust precision and dynamic workspace computation as the two ultimate ones. This paper presents kinematic analysis, workspace, design and control to 3 degrees of freedom (DOF) parallel robots. Parallel robots have received considerable attention from both researchers and manufacturers over the past years because of their potential for high stiffness, low inertia and high speed capability. Therefore, the 3 DOF translation parallel robots provide high potential and good prospects for their practical implementation in human-systems interaction.


Author(s):  
W. Kim ◽  
J. Rastegar

Abstract Trajectory synthesis for robot manipulators with redundant kinematic degrees-of-freedom has been studied by numerous investigators. Redundant manipulators are of interest since the redundant degrees-of-freedom can be used to improve the local and global kinematic and dynamic performance of a system. As a robot manipulator is forced to track a given trajectory, the required actuating torques (forces) may excite the natural modes of vibration of the system. Noting that manipulators with revolute joints have nonlinear dynamics, high harmonic excitation torques are generally generated even though such harmonics have been eliminated from the synthesized trajectories and filtered from the drive inputs. In this paper, a redundancy resolution method is developed based on the Trajectory Pattern Method (TPM) to synthesize trajectories such that the actuating torques required to realize them do not contain higher harmonic components with significant amplitudes. With such trajectories, a robot manipulator can operate at higher speeds and achieve higher tracking accuracy with suppressed residual vibration. As an example, optimal trajectories are synthesized for point to point motions of a plane 3R manipulator.


Author(s):  
Saeed Behzadipour ◽  
Robert Dekker ◽  
Amir Khajepour ◽  
Edmon Chan

The growing needs for high speed positioning devices in the automated manufacturing industry have been challenged by robotic science for more than two decades. Parallel manipulators have been widely used for this purpose due to their advantage of lower moving inertia over the conventional serial manipulators. Cable actuated parallel robots were introduced in 1980’s to reduce the moving inertia even further. In this work, a new cable-based parallel robot is introduced. For this robot, the cables are used not only to actuate the end-effector but also to apply the necessary kinematic constraints to provide three pure translational degrees of freedom. In order to maintain tension in the cables, a passive air cylinder is used to push the end-effector against the stationary platform. In addition to low moving inertia, the new design benefits from simplicity and low manufacturing cost by eliminating joints from the robot’s mechanism. The design procedure and the results of experiments will be discussed in the following.


Author(s):  
M. Necip Sahinkaya ◽  
Robert M. C. Rayner ◽  
Geoff Vernon ◽  
Graham Shirley ◽  
Raj K. Aggarwal

The aim of the work described in this paper is to improve the dynamic performance of a one-degree-of-freedom packaging mechanism through demand signal shaping to minimize the peak to peak motor torque. This enables the mechanism to operate at higher speeds with lower vibration and noise levels, and hence with higher accuracy. Initial experimental tests have shown the motion of the Woodpecker mechanism to suffer from dynamic, vibration problems synonymous with a mechanism possessing large amounts of harmonic content in its output motion. The dynamics of the Woodpecker mechanism and the accompanying servo system are developed and the likely causes of the dynamic issues experienced are identified. A computer model of the complete system drive unit is developed utilizing experimental data. The intention is to use the model in further detailed analytical work to shape the velocity demand signal passed to the system. Inverse dynamics are used to derive the variation in driving torque, which must be exerted on the mechanism crank by the drive motor for the mechanism to achieve a constant speed over the complete cycle. Based on the computer model, a novel technique to shape the speed demand signal is developed and it is shown that significant performance improvements can be achieved without re-synthesizing the mechanism or altering the existing industrial controller.


1975 ◽  
Vol 97 (3) ◽  
pp. 769-775 ◽  
Author(s):  
Fan Y. Chen ◽  
N. Polvanich

The dynamic response of the cam-driven mechanism is investigated for a variety of cam motion profiles. Based on a linear, lumped system model of single degree of freedom, the results of the response characteristics of the follower are presented in the form of nondimensional primary and residual shock response spectra. These spectra are also recasted in four-coordinate log-log grid forms. The extension of this approach to treat the system model of two degrees of freedom is delineated. Furthermore, the analysis of a two-freedom model of the cam-driven system was also undertaken to clarify the effects of many system parameters and for obtaining an optimal design. Fundamental design charts are presented.


2014 ◽  
Vol 1039 ◽  
pp. 368-375
Author(s):  
Chi Lan Cai ◽  
Ya Fei He ◽  
Ning Li ◽  
Qing Zhi Lin

High-speed motorized spindle is the core component of the CNC machines. Its dynamic performance directly affects the accuracy of the geometry, and be the root cause of vibration, noise and temperature increase, etc. Its motor control system has the characteristics of nonlinear and strong coupling, which is one of the key R&D items of the spindle design. Based on granular computing, this paper selects the appropriate granularity to analyze the coupling between the motor control parameters and system performance, and propose a zoning decoupling and optimization method to optimize the overall system performance, which has practical application value.


Author(s):  
Haihong Li ◽  
Zhiyong Yang

The dynamic modeling and analysis of a 2-DOF translational parallel robot for high-speed pick-and-place operation was presented. Considering the flexibility of all links, the governing equation of motion of a flexible link is formulated in the floating frame of reference using Euler-Lagrange method. A kineto-elasto dynamic model of the system is achieved, ready for modal analysis. Simulation in FEM software showed the similar modes with above computational result in typical location and rotation. The dynamic experiment presented the dominant modes and proved the theoretical analysis and simulation. The Diamond robot used in Lithium-ion battery sorting was taken as an example to demonstrate how to finish above studies. The result shows that the mechanism has good dynamic performance. The work is available for all parallel robots with flexible links.


Author(s):  
Se´bastien Briot ◽  
Anatol Pashkevich ◽  
Damien Chablat

In this paper, a new methodology for the optimal design of the secondary geometric parameters (shape of links, size of the platform, etc.) of parallel kinematic machine tools is proposed. This approach aims at minimizing the total mass of the robot under position accuracy constraints. This methodology is applied to two translational parallel robots with three degrees-of-freedom (DOF): the Y-STAR and the UraneSX. The proposed approach is able to speed up the design process and to help the designer to find more quickly a set of design parameters.


Author(s):  
Zhiwei Wang ◽  
Guiming Mei ◽  
Weihua Zhang ◽  
Yao Cheng ◽  
Hangyu Zou ◽  
...  

This study investigates the effects of polygonal wear of wheels on the dynamic performance of the gearbox housing of high-speed trains. First, a dynamics model of the driving system is developed considering gear meshing and flexible deformation of the gearbox housing. Responses of the gearbox housing are calculated using the modal superposition method. Then, a multibody dynamics model of a railway motor car is established considering the driving system. Rig tests in the laboratory and field experiments on the Beijing–Shanghai high-speed rail line are, respectively, performed. Based on the simulation and experiments, the dynamic characteristics of the gearbox housing of the motor car are analysed. The results of the analysis show that polygonal wear can significantly influence the vibration of the gearbox housing, and the maximum amplitude of the acceleration of vibration is more than 200  g. In addition, resonance of the gearbox housing occurs due to the 20th-order polygonal wear. In the resonance region, the oil level sight glass of the gearbox housing vibrates severely, contributing immensely to its cracking.


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