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.

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.

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.

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.

A genetic algorithm-based computed torque control for slider–crank mechanism in the ship’s propeller

2013 ◽  
Vol 228 (12) ◽  
pp. 2090-2099 ◽  
Author(s):  
Farsam Farzadpour ◽  
Hossein Faraji
Keyword(s):  
Genetic Algorithm ◽  
Position Control ◽  
Torque Control ◽  
Process Noise ◽  
Piston Cylinder ◽  
Computed Torque Control ◽  
Control Scheme ◽  
Crank Mechanism ◽  
Parameter Deviation ◽  
Computed Torque

A lot of endeavors regarding the development of slider–crank mechanism in the ship’s propeller have been made and continue to be investigated. This paper presents the position control of a slider–crank mechanism, which is driven by the piston cylinder actuator to adjust the blade pitch angle. An effective motion control strategy known as the computed torque control can ensure global asymptotic stability. However, it is essential for this control scheme to have a precise and accurate system model. Moreover, large amounts of changes in the output and even instability of process are caused by a small amount of measurement or process noise, when the derivative gain is sufficiently large. Accordingly, in order to compensate any parameter deviation and disturbances as well as minimizing errors, we have presented a genetic algorithm-based computed torque control system which adjusts the proportional-derivative gains. Computer simulations are performed which reveals that asymptotically stability is reached and it confirms the effectiveness and high tracking capability of the proposed control scheme.

SIMPLIFIED DYNAMIC MODEL FOR HIGH-SPEED CHECKWEIGHER

2013 ◽  
Vol 24 ◽  
pp. 1360036 ◽  
Author(s):  
YUJI YAMAKAWA ◽  
TAKANORI YAMAZAKI
Keyword(s):  
Dynamic Model ◽  
Measurement System ◽  
High Speed ◽  
Mass Measurement ◽  
Conveyor Belt ◽  
Open Loop ◽  
Model Parameters ◽  
Proposed Model ◽  
Control Scheme ◽  
Mass Damper

In this paper, we concern with the dynamic behaviors of a high speed mass measurement system with conveyor belt (a checkweigher). The goal of this paper is to construct a simple model of the measurement system so as to duplicate a response of the system. The checkweigher with electromagnetic force compensation can be approximated by the combined spring-mass-damper systems as the physical model, and the equation of motion is derived. The model parameters (a damping coefficient and a spring constant) can be obtained from the experimental data for open-loop system. Finally, the validity of the proposed model can be confirmed by comparison of the simulation results with the realistic responses. The simple dynamic model obtained offers practical and useful information to examine control scheme.

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