Shu Wen Lin

A New Method of the Constraints Expression and Handling for Excavator Boom Structural Optimization

In allusion to the deficiencies existing in current structural optimization algorithm of excavator boom such as the inefficiency in expressing and handling the constraints, the insufficiency in adopting the task knowledge to direct constraint handling, and the difficulty in obtaining and adopting the optimal process knowledge, a new method of the constraints expression and handling based on cultural algorithm for excavator boom structural optimization is put forward. The mechanism of hierarchical constraints expression and handing is established to improve the efficiency of the constraint handling in the optimal process with the cultural algorithm as frame and the task knowledge as guide. And the hierarchical topographical knowledge is formed to express tacit knowledge in the population space. Then the process of constraints expressing and handling as well as its interaction with the knowledge base is discussed under the direction of dual evolution in cultural algorithm while the aim of acquisition, expression and handling for tacit constraints knowledge in optimal process is realized. Finally, structural optimization of an excavator boom is taken as an example to demonstrate the effectiveness of this method.

The Geometric Errors Identification of New Methods in Four-Axis Machining Center Axis

A method for fast measuring and identify the six geometric errors of each rotary axes in Four- axis machining center was invented. The method adopted the ball-bar to measure the X, Y, Z direction deviations of the centre block installed on the rotary table in the different rotation angle. And deduced the geometric error identification model in rotary axes based homogeneous transformation, and then identify the axis of the six basic geometric errors. in order to reduce the influence of the inaccuracy of the ball-bar and the reference point position, this paper put forward new method based on the analysis of the sensitivity matrix method, used to guide rational distribution points, so as to improve the error identification accuracy.

Applications of Cultural Ant Colony Optimization in Optimal Excavator Mechanisms Design

In allusion to the low efficiency and unsatisfactory result of the tradional optimization algorithms in existence for engineering design optimization,this paper proposes a cultural ant colony optimization(CACO) algorithm for application in design optimization of excavator’s mechanisms to improve the excavator’s performance efficiently. Through testing and verifying experiments,it is concluded that CACO can discovery knowledge during optimization process and use the knowledge to guide the heuristic searching process,furthermore,it is an appropriate algorithm for the optimization of excavator mechanisms. CACO costs less time and can get better quality solution to improve excavator’s main porformances.

Research on Reconfigurable Method of Open CNC System Software Based on Linux

For the development requirements of high-performance, open CNC system. A reconfigurable and modular upper control software architecture of open CNC system is proposed based on PC+I/O card architecture and Linux software platform. Through this architecture users can quickly customize and develop the required CNC software. Structure model of module with three different levels and each module interfaces are mentioned. Basic consist of upper control software which is achieved by these structure model are introduced. Upper control software modules and communication mechanisms are described. Upper control software of the architecture is achieved on Linux operating system, and the simulation results is given.

Research on the Nonlinear Hysteretic Response Characteristics of Intelligent Vibratory Roller under Horizontal Excitation Mode

This paper introduced Bouc-Wen model to describe the elasticoplastic deformation of compacted soil on horizontal excitation, converts it to a direct polynomial expression using Taylor Expansion based on one order approximation. A 2-def dynamic model was established in terms of the simplified Bouc-Wen model. According to the first order approximation, the equivalent damping coefficient and equivalent stiffness coefficient were deduced through the harmonic linearization method. By means of numerical simulation, during the beginning of compaction ultra harmonics occur in drum, its spectrums present in addition to the fundamental wave only rich odd harmonics. With the increase of soil density during the compaction process, the slipping of the drum on the soil surface may be induced, the drum occurs from periodic motion to quasi periodic motion, its response spectrums and hysteretic loop would change along with the excitation amplitude-frequency changes. In theory the conclusion of the article is valuable to ensure the compaction quality and improve compaction efficiency.

Collaborative Optimization of Excavator Boom Mechanism Parameters under Multiple Loading Conditions

On the base of explaining Multi-Objective Optimization Problems (MOOP) and Collaborative Optimization Techniques (COT), this paper puts forward an original and efficient approach—Collaborative Optimization Technique for Multi-Objective Optimization Problems (COTMOOP)—which combines Collaborative Optimization (CO) techniques and Evolutionary Algorithms (EAs). It has been developed so as to facilitate the organizations and increase the performances of complex coupling systems design and optimization. The newly method has been succeeded in applying to the design and optimization of excavator boom mechanism that is a complex coupling system. The optimal solutions can prove that the approach is efficient and practical.

Research on Geometric Error Model for Multi-Axis CNC Machines Based on Differential Transform

The geometric error of machine axis can be equivalent to the differential movement, regarded as a differential operator based on its ideal position. Thus, a new modeling method for multi-axis CNC machines based on differential transform theory is proposed in this paper. Firstly, the workpiece coordinate system is selected to observe the error of tools cutter location and orientation. Then, the kinematics chain of the machine will be consolidated into one, and the closed chain can be changed to open series type. The transform matrix is adopted to convert the differential operator between the different basis, because of the geometric errors have a different basis between measurement and modeling. Eventually, the general geometric error model for multi-axis machines is established after a XYFZ type three-axis machine is studied in detail.

Discrete Jerk-Limited Feedrate Planning for NURBS Curves Interpolation

In this paper, the jerk-limited feedrate planning is used to adaptively change feedrate with consideration of machine dynamics in the sensitive corners. The curvature is introduced to detect sensitive corner by the look-ahead module to avoid the situation that the curvature is zero. The parameters of every deceleration stages are solved with a series of formula first, and then the feedrate profile is discretized with consideration of the deceleration time, which must be an integer multiple of the interpolation sample time. In addition, the deceleration start point estimation method is described in detail, and a number of deceleration terminal speeds are added into the discrete feedrate profile to drive the machine tool to the right position.

High-Precision Positioning and Speed Smooth Transition Control Algorithm for Terminal Point of Micro-Line Segment

In allusion to the problem of data sampling interpolation error which exists in continuous micro-line segments interpolation algorithm with acceleration /deceleration control, this paper proposes a high-precision positioning and speed smooth transition control algorithm for terminal point of micro-line segment. The linear acceleration/deceleration mode was taken as an example to derive a motion control algorithm, which can eliminate the rounding error of the interpolation with fine adjusting the reserved parameters of acceleration /deceleration process when micro-line segment starting point and terminal point velocity are not zero. Simulation analysis and experiments of motion control shows that the algorithm greatly improves the control accuracy of the joint point position of micro-line segments, achieves the continuous smooth transition at the feed speed of the joint point of adjacent line segments and the uniformity of the velocity in specific line segment.

An Improved Adaptive Interpolation Scheme for NURBS Curve

This paper proposes an improved adaptive NURBS curve interpolation scheme, which keeps a constant feedrate most of the time and adaptively changes feedrate with consideration of machine dynamics. It reserves the advantages of adaptive planning, which has a shorter machining time and a better machining performance, and removes abrupt feedrate changes at the beginning and end of sensitive corner. Furthermore, this method reuses the previous interpolation values during look-ahead planning rather than discard them.