A ball head positioning method based on hybrid force-position control

2021 ◽  
pp. 095965182098790
Author(s):  
Wenmin Chu ◽  
Xiang Huang ◽  
Shuanggao Li ◽  
Peihuang Lou
Keyword(s):  
Position Control ◽  
Lateral Force ◽  
Control Model ◽  
Numerical Control ◽  
Hardware Cost ◽  
Large Component ◽  
Head Positioning ◽  
Positioning Method ◽  
Adjustment System ◽  
Posture Adjustment

In the digital aircraft assembly system, the large component of aircraft is connected with the numerical control locator through a ball joint composed of a ball head and a ball socket. To ensure the posture adjustment accuracy of large component of aircraft, the clearance between the ball head and the ball socket is very small. Therefore, it is very difficult to accurately guide the ball head of large component of aircraft into the ball socket of the numerical control locator. Aiming at this problem, this article proposes a ball head positioning method based on hybrid force-position control, so that the ball socket can approach the ball head adaptively. First, according to the technical characteristics of the ball head positioning, the axes of the numerical control locator are divided into position control axis and force control axis, and the conditions to ensure the safety of ball head positioning are analyzed. Then the control model of ball head positioning based on hybrid force-position control is established and simulated by Simulink. Finally, a simulated posture adjustment system is built in the laboratory, and a series of ball head positioning experiments based on hybrid force-position control are carried out. The experimental results show that, compared with the traditional ball head positioning method, the ball head positioning process based on hybrid force-position control is more stable and faster, and the method can significantly reduce the lateral force. Moreover, the proposed method can be easily integrated into the existing posture adjustment system without additional hardware cost.

Posture adjustment method for large components of aircraft based on hybrid force-position control

2020 ◽  
Vol 47 (3) ◽  
pp. 381-393 ◽  
Author(s):  
Wenmin Chu ◽  
Xiang Huang
Keyword(s):  
Position Control ◽  
Control Method ◽  
Screw Theory ◽  
Interaction Force ◽  
Internal Force ◽  
Numerical Control ◽  
Content Type ◽  
Homogeneous Transformation Matrix ◽  
Adjustment System ◽  
Posture Adjustment

Purpose Flexible tooling for adjusting the posture of large components of aircraft (LCA) is composed of several numerical control locators (NCLs). Because of the manufacture and installation errors of NCL, the traditional control method of NCL may cause great interaction force between NCLs and form the internal force of LCA during the process of posture adjustment. Aiming at this problem, the purpose of this paper is to propose a control method for posture adjustment system based on hybrid force-position control (HFPC) to reduce the internal force of posture adjustment. Design/methodology/approach First of all, the causes of internal force of posture adjustment were analyzed by using homogeneous transformation matrix and inverse kinematics. Then, axles of NCLs were divided into position control axle and force control axle based on the screw theory, and the dynamic characteristics of each axle were simulated by MATLAB. Finally, a simulated posture adjustment system was built in the laboratory to carry out HFPC experiment and was compared with the other two traditional control methods for posture adjustment. Findings The experiment results show that HFPC method for redundant actuated parallel mechanism (RAPM) can significantly reduce the interaction force between NCLs. Originality/value In this paper, HFPC is applied to the control of the posture adjustment system, which reduces the internal force of LCA and improves the assembly quality of aircraft parts.

A calibration method of redundant actuated parallel mechanism for posture adjustment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wenmin Chu ◽  
Xiang Huang ◽  
Shuanggao Li
Keyword(s):  
Parallel Mechanism ◽  
Force Feedback ◽  
Calibration Method ◽  
Numerical Control ◽  
Content Type ◽  
Loop Feedback ◽  
Random Sample Consensus ◽  
Calibration Accuracy ◽  
Adjustment System ◽  
Posture Adjustment

Purpose With the improvement of modern aircraft requirements for safety, long life and economy, higher quality aircraft assembly is needed. However, due to the manufacturing and assembly errors of the posture adjustment mechanism (PAM) used in the digital assembly of aircraft large component (ALC), the posture alignment accuracy of ALC is difficult to be guaranteed, and the posture adjustment stress is easy to be generated. Aiming at these problems, this paper aims to propose a calibration method of redundant actuated parallel mechanism (RAPM) for posture adjustment. Design/methodology/approach First, the kinematics model of the PAM is established, and the influence of the coupling relationship between the axes of the numerical control locators (NCL) is analyzed. Second, the calibration method based on force closed-loop feedback is used to calibrate each branch chain (BC) of the PAM, and the solution of kinematic parameters is optimized by Random Sample Consensus (RANSAC). Third, the uncertainty of kinematic calibration is analyzed by Monte Carlo method. Finally, a simulated posture adjustment system was built to calibrate the kinematics parameters of PAM, and the posture adjustment experiment was carried out according to the calibration results. Findings The experiment results show that the proposed calibration method can significantly improve the posture adjustment accuracy and greatly reduce the posture adjustment stress. Originality/value In this paper, a calibration method based on force feedback is proposed to avoid the deformation of NCL and bracket caused by redundant driving during the calibration process, and RANSAC method is used to reduce the influence of large random error on the calibration accuracy.

FPGA-Based Intelligent Software Hardening Chip for Computer Numerical Control System

2011 ◽  
Vol 105-107 ◽  
pp. 2217-2220
Author(s):  
Mu Lan Wang ◽  
Jian Min Zuo ◽  
Kun Liu ◽  
Xing Hua Zhu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Large Scale ◽  
Position Control ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Cnc System ◽  
Intelligent Software

In order to meet the development demands for high-speed and high-precision of Computer Numerical Control (CNC) machine tools, the equipped CNC systems begin to employ the technical route of software hardening. Making full use of the advanced performance of Large Scale Integrated Circuits (LSIC), this paper puts forward using Field Programmable Gates Array (FPGA) for the functional modules of CNC system, which is called Intelligent Software Hardening Chip (ISHC). The CNC system architecture with high performance is constructed based on the open system thought and ISHCs. The corresponding programs can be designed with Very high speed integrate circuit Hardware Description Language (VHDL) and downloaded into the FPGA. These hardening modules, including the arithmetic module, contour interpolation module, position control module and so on, demonstrate that the proposed schemes are reasonable and feasibility.

An Equivalent-Plane Cross-Coupling Position Control for Contour-Accuracy Improvement in Three-Axis Free-Form Contour Following Tasks

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Jian-Wei Ma ◽  
De-Ning Song ◽  
Zhen-Yuan Jia ◽  
Wen-Wen Jiang ◽  
Fu-Ji Wang ◽  
...  
Keyword(s):  
Error Control ◽  
Position Control ◽  
Three Dimensional ◽  
Cross Coupling ◽  
Experimental Tests ◽  
Numerical Control ◽  
Free Form ◽  
Contouring Error ◽  
Contour Following ◽  
Better Than

To reduce the contouring errors in computer-numerical-control (CNC) contour-following tasks, the cross-coupling controller (CCC) is widely researched and used. However, most existing CCCs are well-designed for two-axis contouring and can hardly be generalized to compensate three-axis curved contour following errors. This paper proposes an equivalent-plane CCC scheme so that most of the two-axis CCCs or flexibly designed algorithms can be utilized for equal control of the three-axis contouring errors. An initial-value regeneration-based Newton method is first proposed to compute the foot point from the actual motion position to the desired contour with a high accuracy, so as to establish the equivalent plane where the estimated three-dimensional contouring-error vector is included. After that, the signed contouring error is computed in the equivalent plane, thus a typical two-axis proportional-integral-differential (PID)-based CCC is utilized for its control. Finally, the two-axis control commands generated by the typical CCC are coupled to three-axis control commands according to the geometry of the established equivalent plane. Experimental tests are conducted to verify the effectiveness of the presented method. The testing results illustrate that the proposed equivalent-plane CCC performs much better than conventional method in both error estimation and error control.

Optimisation of a Polarisation Nephelometer

2021 ◽  
pp. 87-95
Author(s):  
Victor G. Oshlakov ◽  
Anatoly P. Shcherbakov
Keyword(s):  
Personal Computer ◽  
Position Control ◽  
Control Unit ◽  
Numerical Control ◽  
Radiation Beam ◽  
Drive Control ◽  
Control Units ◽  
Smooth Motion ◽  
Approximation Errors ◽  
Scattering Volume

An analysis of the influence caused by polarization nephelometer parameters on the scattering matrix measurement accuracy in a non-isotropic medium is presented. The approximation errors in the actual scattering volume and radiation beam by an elementary scattering volume and an elementary radiation beam are considered. A formula for calculating the nephelometer base is proposed. It is shown that requirements to an irradiation source of a polarizing nephelometer, i.e. mono-chromaticity and high radiation intensity and directivity in a wide spectral range can be satisfied by a set of high brightness LEDs with a radiating (self-luminous) small size body. A 5-wavelength monochromatic irradiation source, with an emission flux of (0.15–0.6) W required for a polarization nephelometer, is described. The design of small-sized polarizing phase control units is shown. An electronic circuit of a radiator control unit based on an AVR-Atmega 8-bit microcontroller with feedback and drive control realized by means of an incremental angular motion sensor and a software PID controller is presented. Precise and smooth motion of the radiator is ensured by standard servo-driven numerical control mathematics and the use of precision gears. The system allows both autonomous adjustment of the radiator’s reference positions and adjustment by means of commands from a personal computer. Both the computer and microcontroller programs were developed with the use of free software, making it possible to transfer the programs to Windows‑7(10), Linux and embedded Linux operating systems. Communication between the radiator’s position control system and the personal computer is realised by means of a standard noise immune USB-RS485 interface.

scholarly journals DESAIN SISTEM KENDALI UMPAN BALIK STATE PADA KASUS KONTINYU UNTUK MEJA KERJA CNC

2019 ◽  
Vol 20 (2) ◽  
pp. 32
Author(s):  
Fakhruddin Mangkusasmito ◽  
Tsani Hendro Nugroho
Keyword(s):  
Control System ◽  
Rise Time ◽  
Manufacturing Industry ◽  
Position Control ◽  
Control Method ◽  
Tracking System ◽  
Settling Time ◽  
Numerical Control ◽  
Pole Placement ◽  
Work Table

Fakhruddin Mangkusasmito, Tsani Hendro Nugroho in this paper explain that One of the important control system in the manufacturing industry is the position control. Mainly in the Computer Numerical Control (CNC) machine, work-table motion control system is used to regulate work-table movements when the machine process a workpieces on it. On standard machines, work-table movements are two axes (X-Y), which is driven by a motor and lead-screw. The discussion in this research only focus on one axis assuming that the systems on both axes are the same and independent. In this research, MATLAB is used to describe the behaviour of the system and also to design appropriate control system in continuos system using state feedback linear controller such as pole placement , tracking system, full order compensator and reduced order compensator. The goal is to obtain a fast response with a rapid rise time and settling time to a step command, while not exceeding an overshoot of 5%. The specification are than a percent overshoot equal to1%, 0,05s settling time and 0,03s rise time. The performance of each control methods are simulated and analyzed to decide the best suit control method for the systems with such criteria. And the result verify that using tracking system controller method achieve such specification with 0% overshoot, 0,04s settling time and 0,028s rise time.

scholarly journals Position-Posture Control of Multilegged Walking Robot Based on Kinematic Correction

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Liang Zhang ◽  
Yaguang Zhu ◽  
Feifei Zhang ◽  
Shuangjie Zhou
Keyword(s):  
Position Control ◽  
Body Position ◽  
Control Process ◽  
The Body ◽  
Posture Control ◽  
Effective Control ◽  
Adjustment Process ◽  
Multilegged Walking Robot ◽  
Posture Adjustment ◽  
Robot Platform

Posture-position control is the fundamental technology among multilegged robots as it is hard to get an effective control on rough terrain. These robots need to constantly adjust the position-posture of its body to move stalely and flexibly. However, the actual footholds of the robot constantly changing cause serious errors during the position-posture control process because their foot-ends are basically in nonpoint contact with the ground. Therefore, a position-posture control algorithm for multilegged robots based on kinematic correction is proposed in this paper. Position-posture adjustment is divided into two independent motion processes: robot body position adjustment and posture adjustment. First, for the two separate adjustment processes, the positions of the footholds relative to the body are obtained and their positions relative to the body get through motion synthesis. Then, according to the modified inverse kinematics solution, the joint angles of the robot are worked out. Unlike the traditional complex closed-loop position-posture control of the robot, the algorithm proposed in this paper can achieve the purpose of reducing errors in the position-posture adjustment process of the leg-foot robot through a simple and general kinematic modification. Finally, this method is applied in the motion control of a bionic hexapod robot platform with a hemispherical foot-end. A comparison experiment of linear position-posture change on the flat ground shows that this method can reduce the attitude errors, especially the heading error reduced by 55.46%.

The Impact Analysis of Digital Controller Hardware Parameters of AMB on Control Precision

2012 ◽  
Vol 150 ◽  
pp. 111-115
Author(s):  
Yu Min Yang ◽  
Xi Ping Wang ◽  
Li Guo ◽  
Man Fan
Keyword(s):  
Digital Control ◽  
Impact Analysis ◽  
Control Model ◽  
Magnetic Bearing ◽  
Numerical Control ◽  
Digital Controller ◽  
Numerical Control System ◽  
Control Precision ◽  
The Impact ◽  
Control Accuracy

Digital control circuit for the hardware components, the impact of parameters on the control precision is analyzed. The digital control model is derived according to the requirements control of magnetic bearing system in this paper .Control accuracy and the prediction of control accuracy can be achieved by he theoretical estimates when numerical control system is given .For the future, it provides a simple and efficient method for estimating control accuracy of numerical controller.

scholarly journals The Influence of Servo Drive Control on the NC Vertical Milling Machine Dynamic Compliance

2020 ◽  
Vol 4 (4) ◽  
pp. 111
Author(s):  
Jan Grau ◽  
Pavel Souček ◽  
Matěj Sulitka
Keyword(s):  
Machine Tool ◽  
Position Control ◽  
Dynamic Compliance ◽  
Numerical Control ◽  
Machining Process ◽  
Servo Drive ◽  
Compliance Matrix ◽  
Mechanical Structure ◽  
Feed Drive ◽  
Drive Control

A model Numerical Control (NC) machine tool dynamic compliance is analyzed, including the influence of its mechanical structure and position control feed drive algorithms. The dynamic model of the machine tool is divided into two main parts, which are closest to the machining process. First, the milling head assembly group is presented as a system of one mass oscillating in a 2D plane and 3D space. Second, the motion axes assembly group, XY cross table with linear feed drive, is presented. A square 2×2 dimension matrix of the total dynamic compliance is evaluated within the feed drive control system included. Partial elements of the mechanical structure dynamic compliance matrix of the general N×N dimension are contained in the total dynamic compliance matrix.

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