Error Compensation Algorithms for Sculptured Surface Production

1994 ◽  
Vol 116 (2) ◽  
pp. 144-152 ◽  
Author(s):  
W. R. Dinauer ◽  
N. A. Duffie ◽  
M. L. Philpott
Keyword(s):  
Error Analysis ◽  
Error Compensation ◽  
Closed Loop ◽  
Production Control ◽  
Open Loop ◽  
Cnc Machining ◽  
Surface Finishing ◽  
Sculptured Surface ◽  
Control Surfaces ◽  
Surface Production

Four algorithms for removing shape and waviness errors in sculptured surface production processes are described in the paper. One of the algorithms employs an open-loop strategy without inspection, error analysis, and error compensation. The other three algorithms employ closed-loop inspection error analysis and error compensation strategies to manipulate control surfaces used in sculptured surface production. Coordinate measurements made on the surface being produced are compared with a designed surface and the results are used to modify related control surfaces that are used to guide processing equipment. Two of the closed-loop algorithms also use intermediate planned surfaces to improve error compensation and production control. Experiments are described in the paper in which the algorithms were tested on an experimental surface finishing system that included an optical probe, grinding spindle, and computer control system integrated with a CNC machining center. The results obtained using open-loop and closed-loop algorithms are compared, and it is shown that surface inspection, surface error analysis, surface compensation, and surface grinding can be iteratively applied to converge rough-machined test surfaces to their designed shape. The closed-loop algorithms are shown to be capable of compensating for disturbances in the finishing process that went undetected when the open-loop algorithm was used. The closed-loop algorithms have significant potential for application in automated finishing systems for molds and dies.

An Error Compensation Strategy for Replication by Rapid Prototyping

1995 ◽  
Vol 117 (3) ◽  
pp. 423-429 ◽  
Author(s):  
M. L. Philpott ◽  
P. A. Green
Keyword(s):  
Rapid Prototyping ◽  
Error Compensation ◽  
Cnc Machining ◽  
Surface Finishing ◽  
Internal Stresses ◽  
Replication Process ◽  
Surface Errors ◽  
Abrasive Finishing ◽  
Finishing Processes ◽  
Mechanical Surface

A generic closed-loop strategy for error compensation is presented which extracts and mathematically models the geometry of sculptured artifacts, and compensates for cumulative error build-up during replication. Experimental results using this strategy demonstrate that a considerable improvement in the accuracy of the end product can be achieved. The replication process involves scanning, CAD solid model creation, rapid prototyping utilizing the stereolithography process, the production of room temperature vulcanized (RTV) molds, the casting of polyurethane parts from the RTV mold, abrasive finishing processes associated with these prototyping processes, and the CNC machining of production molds and dies. At each stage in the replication process, the surface errors (caused primarily by material shrinkage, layer curling, internal stresses, chemical curing phenomena, and material removal during mechanical surface finishing) are tracked and used in subsequent production, through an iterative process of surface fitting and surface compensation.

Research on Workpiece Machining Precision PID Control Model in Closed-Loop Manufacturing Systems

2009 ◽  
Vol 16-19 ◽  
pp. 1174-1178 ◽  
Author(s):  
Jun Lu ◽  
Yu Mei Huang ◽  
Yang Liu ◽  
Wen Wen Li ◽  
Hua Zhong
Keyword(s):  
Experimental Method ◽  
Pid Control ◽  
Error Compensation ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Closed Loop ◽  
Control Model ◽  
Cnc Machining ◽  
Machining Error ◽  
Machining Precision

In this article, a new concept named ‘Closed-loop Manufacturing System’ (CLMS) is introduced. The Workpiece Machining Precision PID Control Model (WMPPCM) is proposed and described. PID error compensation model expressions are structured. The experimental method of WMPPCM is established. In the experiment, WMPPCM could be utilized to estimate the trend of machining error so as to conduct the adjustment before production. The experiment has verified the feasibility and validity of WMPPCM. The experiments have also proved that WMPPCM can decrease machining error more effectively then traditional CNC machining method.

Error Analysis of Closed-Loop Control for Spacecraft Orbital Transfer Using Monte Carlo Method

2013 ◽  
Vol 765-767 ◽  
pp. 1998-2003
Author(s):  
Yang Zhou ◽  
Ye Yan ◽  
Xu Huang ◽  
Teng Yi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Error Analysis ◽  
Closed Loop ◽  
Open Loop ◽  
Closed Loop Control ◽  
Orbital Transfer ◽  
Loop Control ◽  
True State ◽  
Correction Maneuver

The true trajectory of spacecraft disperses from the nominal due to kinds of errors and perturbations, including environment, actuator and sensor uncertainties. This paper studies the error analysis problem of closed-loop control for spacecraft orbital transfer via Monte Carlo method. At first, errors that affect the true state are introduced and a navigation-target-correction loop system for Monte Carlo simulation is built. A dynamical model for orbital transfer is established, based on which both the extended Kalman filter (EKF) algorithm and correction maneuver control algorithm are developed. Precision analysis is studied of high eccentric orbital (HEO) transfer under open-loop and closed-loop control respectively. The simulation results prove the validity of the proposed method.

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

scholarly journals Parallel Point Clouds: Hybrid Point Cloud Generation and 3D Model Enhancement via Virtual–Real Integration

2021 ◽  
Vol 13 (15) ◽  
pp. 2868
Author(s):  
Yonglin Tian ◽  
Xiao Wang ◽  
Yu Shen ◽  
Zhongzheng Guo ◽  
Zilei Wang ◽  
...  
Keyword(s):  
Point Cloud ◽  
Closed Loop ◽  
Real Data ◽  
Point Clouds ◽  
Autonomous Driving ◽  
Training Model ◽  
Labor Cost ◽  
Open Loop ◽  
Training Dataset ◽  
Data Annotation

Three-dimensional information perception from point clouds is of vital importance for improving the ability of machines to understand the world, especially for autonomous driving and unmanned aerial vehicles. Data annotation for point clouds is one of the most challenging and costly tasks. In this paper, we propose a closed-loop and virtual–real interactive point cloud generation and model-upgrading framework called Parallel Point Clouds (PPCs). To our best knowledge, this is the first time that the training model has been changed from an open-loop to a closed-loop mechanism. The feedback from the evaluation results is used to update the training dataset, benefiting from the flexibility of artificial scenes. Under the framework, a point-based LiDAR simulation model is proposed, which greatly simplifies the scanning operation. Besides, a group-based placing method is put forward to integrate hybrid point clouds, via locating candidate positions for virtual objects in real scenes. Taking advantage of the CAD models and mobile LiDAR devices, two hybrid point cloud datasets, i.e., ShapeKITTI and MobilePointClouds, are built for 3D detection tasks. With almost zero labor cost on data annotation for newly added objects, the models (PointPillars) trained with ShapeKITTI and MobilePointClouds achieved 78.6% and 60.0% of the average precision of the model trained with real data on 3D detection, respectively.

scholarly journals Converting MST to TSP Path by Branch Elimination

2020 ◽  
Vol 11 (1) ◽  
pp. 177
Author(s):  
Pasi Fränti ◽  
Teemu Nenonen ◽  
Mingchuan Yuan
Keyword(s):  
Spanning Tree ◽  
Closed Loop ◽  
Minimum Spanning Tree ◽  
Travelling Salesman Problem ◽  
Open Loop ◽  
Travelling Salesman ◽  
Elimination Algorithm ◽  
Number Of Iterations ◽  
Number Of Branches

Travelling salesman problem (TSP) has been widely studied for the classical closed loop variant but less attention has been paid to the open loop variant. Open loop solution has property of being also a spanning tree, although not necessarily the minimum spanning tree (MST). In this paper, we present a simple branch elimination algorithm that removes the branches from MST by cutting one link and then reconnecting the resulting subtrees via selected leaf nodes. The number of iterations equals to the number of branches (b) in the MST. Typically, b << n where n is the number of nodes. With O-Mopsi and Dots datasets, the algorithm reaches gap of 1.69% and 0.61 %, respectively. The algorithm is suitable especially for educational purposes by showing the connection between MST and TSP, but it can also serve as a quick approximation for more complex metaheuristics whose efficiency relies on quality of the initial solution.

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