The Influence of Partial Force Balancing on the Shaking Moments, Contact Forces, and Precision of a Delta Robot-Like Manipulator in a Compliant Frame

2018 ◽  
Author(s):  
Jan J. de Jong ◽  
J. P. Meijaard ◽  
Volkert van der Wijk
Keyword(s):  
High Speed ◽  
Contact Forces ◽  
Force Balance ◽  
Dynamic Loads ◽  
Accuracy Improvement ◽  
End Effector ◽  
Pick And Place ◽  
Delta Robot ◽  
Full Force ◽  
Typical Design

For the Delta robot, a high-speed parallel pick-and-place manipulator, base vibrations are a significant problem. Especially since the Delta robot is suspended above its workpiece, it requires a large, stiff, and heavy base frame for fast and accurate motions. Dynamic balancing of the shaking forces and the shaking moments is a known technique to reduce the dynamic loads on the base frame and to the surroundings. In this paper it is investigated how solely with partial force balancing, dynamic loads and pick-and-place accuracy of a Delta robot-like manipulator can be improved, considering also the compliance of the base frame. This is done since partial force balance solutions can be implemented relatively simply in the current Delta robot designs, whereas full force and moment balance solutions are complex to apply in practice. Numerical simulations with a representative planar model of a Delta robot-like manipulator with a compliant base frame show that with an increasing amount of force balance the shaking moments increase up to 16% for full force balance. The floor contact forces first reduce and then increase with increasing force balance. With 43% force balance the floor contact forces are minimal, giving a 63% reduction. The end-effector accuracy slightly improves with increasing force balance until full force balance yields a 31% accuracy improvement. A further increase of the force (over) balance shows a 59% improvement of end-effector accuracy for 350% force balance. These effects are mainly due to the typical design of the Delta robot base frame and the way the robot is mounted to it.

Asymmetric Arm Design on Delta Robot System

2014 ◽  
Author(s):  
Tsung-Liang Wu ◽  
Jih-Hsiang Yeh ◽  
Cheng-Chen Yang
Keyword(s):  
Energy Saving ◽  
High Speed ◽  
Kinematic Model ◽  
Industrial Applications ◽  
Critical Parameters ◽  
Robot System ◽  
System Cost ◽  
Excited Vibration ◽  
Pick And Place ◽  
Delta Robot

The Delta robot system is widely used in high speed (4 cycles/s at 25-200-25 mm) pick-and-place process in production line. Some industrial applications include photo-voltaic (PV), food process, and electronic assembly, and so on. The energy saving and system cost are two critical parameters for designing the next generation of pick-and-place system. To achieve these goals, a light-weight moving structure with sufficient strength to overcome the excited vibration will be one of the solutions. In this paper, an asymmetric arm design is proposed and fabricated to gain the benefit of strength-to-weight. The asymmetric arm is designed by reinforcing a specific direction and is validated the vibration suppression capability both by simulation and experiment. A position controller that is derived from the kinematic model of Delta robot is utilized to manipulate the robot under a forward-backward motion with a polynomial trajectory with 200 mm displacement. The residual vibration, then, was measured after the forward-backward motion to compare the settling performance between symmetric- and asymmetric-arms on the Delta robot system, respectively. The results conclude as following: (1) The asymmetric arms perform slightly worse (0.03 sec more in settling time) than symmetric arm but there is 15% weight reducing comparing to symmetric arm. (2) Both energy saving and system cost reducing would be achieved by utilizing actuators with lower power consumption and fabrication on carbon fiber arms with mass customization.

scholarly journals Reducing the Frame Vibration of Delta Robot in Pick and Place Application: An Acceleration Profile Optimization Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Hongtai Cheng ◽  
Wei Li
Keyword(s):  
Surrogate Model ◽  
High Speed ◽  
Gaussian Process Regression ◽  
Frame Structure ◽  
Manufacturing Cost ◽  
Optimization Approach ◽  
Pick And Place ◽  
Delta Robot ◽  
Profile Optimization ◽  
Acceleration Profile

Delta robot is typically mounted on a frame and performs high speed pick and place tasks from top to bottom. Because of its outstanding accelerating capability and higher center of mass, the Delta robot can generate significant frame vibration. Existing trajectory smoothing methods mainly focus on vibration reduction for the robot instead of the frame, and modifying the frame structure increases the manufacturing cost. In this paper, an acceleration profile optimization approach is proposed to reduce the Delta robot-frame vibration. The profile is determined by the maximum jerk, acceleration, and velocity. The pick and place motion (PPM) and resulting frame vibration are analyzed in frequency domain. Quantitative analysis shows that frame vibration can be reduced by altering those dynamic motion parameters. Because the analytic model is derived based on several simplifications, it cannot be directly applied. A surrogate model-based optimization method is proposed to solve the practical issues. By directly executing the PPM with different parameters and measuring the vibration, a model is derived using Gaussian Process Regression (GPR). In order to reduce the frame vibration without sacrificing robot efficiency, those two goals are fused together according to their priorities. Based on the surrogate model, a single objective optimization problem is formulated and solved by Genetic Algorithm (GA). Experimental results show effectiveness of the proposed method. Behavior of the optimal parameters also verifies the robot-frame vibration mechanism.

A Comparative Study on the Pick-and-Place Trajectories for a Delta Robot

2016 ◽  
Author(s):  
Zexiao Xie ◽  
Peixin Wu ◽  
Ping Ren
Keyword(s):  
Comparative Study ◽  
High Speed ◽  
Computation Time ◽  
Optimization Methods ◽  
Terminal State ◽  
Industrial Robots ◽  
Piecewise Polynomials ◽  
Pick And Place ◽  
Dynamic Performances ◽  
Delta Robot

A comparative study on the pick-and-place trajectories for high-speed Delta robots is presented in this paper. The Adept Cycle has been widely accepted as a standardized pick-and-place trajectory for industrial robots. The blending curves and optimization methods to smooth this trajectory are briefly surveyed. Three major types of trajectories: Lamé curves, clothoids and piecewise polynomials, are selected as candidates to be compared. The processes to generate these trajectories are briefly reviewed. The trajectories are firstly compared in term of their computation time. Then, based on a dynamic model and an experimental prototype of the Delta robot, different combinations of the geometric paths and motion profiles are compared in terms of power consumption, terminal state accuracy and residual vibration. The effects of trajectory configurations and parameters on the robot’s dynamic performances are investigated. Through a comprehensive analysis on both simulation and experimental results, a near-optimal pick-and-place trajectory for the Delta robot is identified and validated.

Design and Fabrication of Flexible Three Link Manipulator for Pick and Place Application

2014 ◽  
Vol 592-594 ◽  
pp. 2134-2138
Author(s):  
S.K. Naveen ◽  
Kumaar Devaraj Rajesh ◽  
P. Pal Pandian
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Lower Energy ◽  
High Speed ◽  
Good Accuracy ◽  
Industrial Robot ◽  
Flexible Manipulator ◽  
End Effector ◽  
Unstructured Environments ◽  
Pick And Place

Flexibility plays a key role in robot based applications, where the ability to perform complex tasks in semi structured or even unstructured environments is strategic.Most industrial robot operates inside a security fence which separates them from human workers, but not all. Flexibility, lightness in relation to the mass to be displaced and energy efficiency are acquiring increasing significance in automation. We can achieve higher performance in robots by optimizing the parameters like high-speed operation, lower energy consumption, lighter weight and safer operation. In this paper a pick and place robot is designed and developed to achieve effective automation with higher safety and with greater ease. The main objectives of designing this flexible manipulator are to reduce its mass and to minimize its vibrations in the end-effector, which enhances good accuracy in positioning.This can be achieved by bringing down the number of working components and jointswhich reduce various losses. The greater mass can be transferred from one place to another place with relatively lesser mass of flexible three link manipulator. The various problems were encountered and rectified during the design and fabrication of flexible three link manipulator for pick and place application.

scholarly journals Tolerance Design and Kinematic Calibration of a Four-Degrees-of-Freedom Pick-and-Place Parallel Robot

2016 ◽  
Vol 8 (6) ◽  
Author(s):  
Tian Huang ◽  
Pujun Bai ◽  
Jiangping Mei ◽  
Derek G. Chetwynd
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Simplified Model ◽  
Tolerance Design ◽  
Kinematic Calibration ◽  
Distance Measurements ◽  
End Effector ◽  
Pick And Place ◽  
Source Errors

This paper presents a comprehensive methodology for ensuring the geometric pose accuracy of a 4DOF high-speed pick-and-place parallel robot having an articulated traveling plate. The process is implemented by four steps: (1) formulation of the error model containing all possible geometric source errors; (2) tolerance design of the source errors affecting the uncompensatable pose accuracy via sensitivity analysis; (3) identification of the source errors affecting the compensatable pose accuracy via a simplified model and distance measurements; and (4) development of a linearized error compensator for real-time implementation. Experimental results show that a tilt angular accuracy of 0.1/100 and a volumetric/rotational accuracy of 0.5 mm/±0.8 deg of the end-effector can be achieved over the cylindrical task workspace.

Dynamic Conveyor Tracking Control of a Delta Robot

2016 ◽  
Vol 679 ◽  
pp. 43-48 ◽  
Author(s):  
Guo Ying Zhang ◽  
Guan Feng Liu ◽  
Xiao Bin Guo ◽  
Xie Yuan Lin
Keyword(s):  
High Speed ◽  
Vision System ◽  
Conveyor Belt ◽  
Torque Control ◽  
Tracking Problem ◽  
Control Scheme ◽  
Pick And Place ◽  
Time Position ◽  
Delta Robot ◽  
Computed Torque

For general dynamic pick and place tasks that the objects are transferred with high speed by the conveyor belt, the capability of a delta robot to track the traveling objects is very important for the efficiency. To meet the needs of precision and smooth control, a computed-torque control scheme for conveyor tracking is implemented in this paper. For higher efficiency and accuracy, computer vision system, encoder and conveyor belt region are incorporated into the control scheme. Dividing the conveyor belt into three regions, the robot is commanded to track, pick and give up according to the subregions. Conveyor belt is equipped with an encoder that provides the controller with real-time position and speed of the belt. Based upon those informations, the controller automatically compensates the end positions with respect to the belt to adjust for the position of the conveyor. Then, the conveyor tracking problem is converted to a subregional tracking problem.

Kinematic calibration of the parallel Delta robot

Robotica ◽  
1998 ◽  
Vol 16 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Peter Vischer ◽  
Reymond Clavel
Keyword(s):  
Calibration Model ◽  
Kinematic Calibration ◽  
Accuracy Improvement ◽  
End Effector ◽  
Mechanical Parts ◽  
Perfect Model ◽  
Calibration Models ◽  
Position And Orientation ◽  
Delta Robot ◽  
Set Up

This article deals with the kinematic calibration of the Delta robot. Two different calibration models are introduced: The first one takes into account deviations of all mechanical parts except the spherical joints, which are assumed to be perfect (“model 54”), the second model considers only deviations which affect the position of the end-effector, but not its orientation, assuming that the “spatial parallelogram” remains perfect (“model 24”). A measurement set-up is presented which allows to determine the end-effector's position and orientation with respect to the base. The measurement points are later be used to identify the parameters of the two calibration model resulting in an accuracy improvement of a factor of 12.3 for the position and a factor of 3.7 for the prediction of the orientation.

scholarly journals Design and Development of Multipurpose Delta Robot

2021 ◽  
Vol 9 (8) ◽  
pp. 1471-1475
Author(s):  
Dr. Anil Sahu
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Maximum Acceleration ◽  
Work Volume ◽  
Pick And Place ◽  
Fast Motion ◽  
Delta Robot ◽  
Cost Efficient ◽  
Parallel Configuration ◽  
Future Work

Abstract: This report represents an designing and simulating ideal pick and place robot which should carry out the operations in minimum time and should also be cost efficient. It is four degrees of freedom parallel configuration used for very high speed pick and place operations. The objectives of this report are designing a Delta robot capable of carrying 1kg payload, achieving a cycle rate of 120 cycles per minute covering a work volume of 400x300x200 mm3. The project involves Kinematic & Dynamic modeling of the robot for the above specifications. The kinematic parameters, involving the lengths of the bicep and forearm, are calculated based on the work volume requirements and the dynamic parameters, involving the motor torque and speed, are calculated based on the maximum acceleration requirements and the inertia of the system. The project further involves the structural analysis of the robot which deals with the proper sizing of the mechanical structure which should be capable of withstanding the high torque and acceleration required for smooth and fast motion. The future work involves integrating the mechanical system with the control system and programming the system for a particular application

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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