Cui Ma

Event‐based cooperative control of a high‐speed bar‐tacking sewing machine

Purpose – Bar‐tacking is a specialized sewing stitch designed to provide immense tensile strength to the garment which requires a high‐speed precision bar‐tacking sewing machine. This paper aims to present an event‐driven multi‐axis cooperative control method for a bar‐tacking sewing machine.Design/methodology/approach – The control method consists of two parts: the multi‐axis cooperative control and the needle stop positioning control. The challenges include the high speed and the precision. For example, the needle must stop at a set position in milliseconds.Findings – The presented multi‐axis cooperative control can ensure the high speed response and the precision of the cooperative control. The needle stop positioning control is based on a combination of the velocity control and the position control with velocity feed‐forward and limitation.Research limitations/implications – The bar‐tacking sewing machine requires high‐speed start and stop response and coordination of displacement and velocity only at...

An Improved Demon Registration with Mutual Information for Non-Rigid Medical Images

Non-rigid image registration plays an important role in medical imaging. Classic Demons algorithm is a good method for image registration in some domain. One disadvantage of classic Demons algorithm is that the topological preservation can not be ensured, and it can only adapt to deal with the single modality image registration. In medical image analysis, the different modal images comparison and fusion are needed to give the doctor enough information for making a decision. The mutual information algorithm has been validated useful for multi-modality image registration. By analyzing the critical points of Demons registration like mis-registration, an improved Demons algorithm with mutual information evaluation is proposed. Experiment results on liver images between CT and MRI modality show that the proposed algorithm can deal with multi-modality image registration well and it can hold the abilities even faces the noise and distortion.

Research of High Performance Closed Loop Control System for Stepper Motor

A control system of double closed-loop for two-phase hybrid stepper motor which includes speed closed-loop and current closed-loop is established on the basis of fuzzy-PID control algorithm, space vector pulse width modulation (SVPWM) method, space vector conversion and mathematical modeling of stepper motor. In the control system, the stepper motor model is established according to the mathematic model; the current and speed of stepper motor are controlled in feedback by the adopting fuzzy-PID control algorithm; the space vector conversion is carried out in the current/voltage conversion section, and the space vector pulse width modulation method is used to produce pwm wave. The performance of the doubled closed-loop control system for stepper motor is analyzed by the powerful modeling and simulation function of MATLAB/Simulink. The simulation results show that the control system has favorable control performance and dynamics characteristics.

Liver Image Segmentation Using Improved Watershed Method

This paper introduces an improved watershed algorithm for liver image segmentation. Medical images have complicated structure and the soft tissues have deformation sometimes. To exactly conduct the following image registration or surgery navigation, the image segmentation must identify the changes quickly and accurately. Watershed algorithm has fast speed and good edge location for complex structure, but it is sensitive to noise and has the over-segmentation problem. In this paper, pre-processing and post-processing methods are proposed during watershed segmentation procedure. According to the thresholds of region area and gray difference between adjacent regions, the image noise is reduced at pre-processing stage and the over-segmented regions are merged at post-processing part. Through the experiment of two similar liver images, we can see the segmented images have clear outline and the difference of two images can be identified obviously.

Energy Wave Transmission and Control Analysis in Force Reflection Teleoperation Based on Interconnected Power Line

Force-Reflected Telepresence Teleoperation system has been widely used. Generally, force and torque sensors are installed on the robot to realize haptic perception. Control commands and force-reflected information from the robot are transmitted by communication link, such as internet. However, this structure not only brings difficulties of installation and commissioning, but also reduces the system flexibility and makes control more difficult. And it is prone to interfered in microenvironment. This paper presents a new type of energy transfer method to achieve it by power line instead of internet between the Master-slave Manipulators. This method achieves the consistency of force-reflected without using sensors to measure the conditions. In practical application, it requires to design an energy managed controller to insure the stability and obtain precision in synchronization between the master part and slave part. This paper gives the theory, the system structure and control method of force telepresence teleoperation based on power line.

Mechatronic cooperative design and simulation of a multi-axis bar tacking machine

In this paper, a new method to design bar tacking machine is introduced. According to multidiscipline model design rule, mechanical, kinematic and control model of the bar tacking machine are constructed. Based on such models, a mechatronic cooperative design and simulation environment is setup by using RecurDyn and Matlab/simulink software. By analyzing the working condition of this machine and using them as the input, some working results can be got from the environment. Ideal output is reached by modifying the design schedule and parameter. By this method, designing efficiency is improved and the testing cost is reduced.

Software implementation of bar tacker control system

This paper presents a multi-axis control system of bar tacker. A bar tacker must meet the following requirements: feeding accurately, cutting automatically, needle stopping precisely and quickly, et ac. In order to achieve these functions, multi-thread synchronization control was introduced to ensure the multi-axis collaborative motion. And time-based PI method with velocity feed-forward was used to control the needle stop position. The software of this control system was programmed based on embedded Windows platform. At present this control system has been tested in the factory and the test results show that this method can accurately control the multi-axis motion and produce good sewing patterns. Besides lockstitch bar tacker, this control system can also be applied to other intelligent sewing machines by minor changes and improvement.