Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the a...Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap, instead of the traditional methods that depend on experiential models or intermittent compensation. However, the effects of process parameters on 3D SSMEDM have not been reported up until now. In this study, the emphasis is laid on the effects of pulse duration, peak current, machining polarity, track style, track overlap, and scanning velocity on the 3D SSMEDM performances of machining efficiency, processing status, and surface accuracy. A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon. The experimental results were obtained as follows. Peak current plays a main role in machining efficiency and surface accuracy. Pulse duration affects obviously the stability of discharge state. The material removal rate of cathode processing is about 3/5 of that of anode processing. Compared with direction-parallel path, contour-parallel path is better in counteracting the lateral wear of tool electrode end. Scanning velocity should be selected moderately to avoid electric arc and short. Track overlap should be slightly less than the radius of tool electrode. In addition, a typical 3D micro structure of eye shape was machined based on the optimized process parameters. These results are beneficial to improve machining stability, accuracy, and efficiency in 3D SSMEDM.展开更多
Performance of giant magnetostrictive material (GMM) is introduced. Principleof work, basic structure and key techniques of giant magnetostrictive actuator (GMA) are analyzed.Its dynamic models of magneto-mechanical c...Performance of giant magnetostrictive material (GMM) is introduced. Principleof work, basic structure and key techniques of giant magnetostrictive actuator (GMA) are analyzed.Its dynamic models of magneto-mechanical coupling are established. The structure and principle ofthe pneumatic servo valve and the micro pipe robot with new homemade GMM are presented. Theexperiment is carried out under typical working conditions. The experiment results show that the GMMpneumatic servo valve has wide pressure control characteristics, good linearity, and fast responsespeed. The movement principles of the GMM robot system are reliably feasible and its maximal movingspeed is about 8 mm/s. It is preferable to the driving frequency of the robot within 100 approx 300Hz.展开更多
An experimental study of micro-tool servo with electrostrictive actuator is presented.The design methods as well as the performance of the entire mechanism is given out.The results of the experiment show that the reso...An experimental study of micro-tool servo with electrostrictive actuator is presented.The design methods as well as the performance of the entire mechanism is given out.The results of the experiment show that the resolution of the micro-tool servo is 0.02μm and the frequency response is up to 200Hz,which satisfies the requirements of the ultra-precision machining.展开更多
This paper presents an improved support vector machine （SVM） algorithm, which employs invariant moments-based edge extraction to obtain feature attribute. A heuristic attribute reduction algorithm based on rough set...This paper presents an improved support vector machine （SVM） algorithm, which employs invariant moments-based edge extraction to obtain feature attribute. A heuristic attribute reduction algorithm based on rough set＇s discernible matrix is proposed to identify and classify micro-targets. To avoid the complicated calibration for intrinsic parameters of camera, an improved Broyden＇s method is proposed to estimate the image Jacobian matrix which employs Chebyshev polynomial to construct a cost function to approximate the optimization value. Finally, a visual controller is designed for a robotic micromanipulation system. The experiment results of micro-parts assembly show that the proposed methods and algorithms are effective and feasible.展开更多
为解决YB95A条外透明纸包装机在透明纸展开切割和传送过程中出现透明纸偏移、长度变化等问题，借鉴YB917条外透明纸包装机的透明纸传送原理，通过增加伺服电机、传感器、编码器和电控程序等，将YB95A条外透明纸传送由主传动驱动改为伺...为解决YB95A条外透明纸包装机在透明纸展开切割和传送过程中出现透明纸偏移、长度变化等问题，借鉴YB917条外透明纸包装机的透明纸传送原理，通过增加伺服电机、传感器、编码器和电控程序等，将YB95A条外透明纸传送由主传动驱动改为伺服控制的独立传送，将独立传送装置的电控部分融于MICROⅡ控制系统，控制程序加入到MICROⅡ控制软件中，通过调整IPC（Industrial Personal Computer）的相关参数对透明纸长度和搭口位置进行调整。结果表明，透明纸传送误差由±2mm降低到±0．5mm，实现了透明纸切割长度、传送位置的自动调整；条烟废品率由20～25条／d减少到0～2条／d，有效提高了卷烟包装品质。改进后YB95A条外透明纸包装机适用于彩膜包装，满足了现代卷烟企业对包装材料多样化的需求。展开更多
The quality of the micro-mechanical machining outcome depends significantly on the tracking performance of the miniaturized linear motor drive precision stage. The tracking behavior of a direct drive design is prone t...The quality of the micro-mechanical machining outcome depends significantly on the tracking performance of the miniaturized linear motor drive precision stage. The tracking behavior of a direct drive design is prone to uncertainties such as model parameter variations and disturbances. Robust optimal tracking controller design for this kind of precision stages with mass and damping ratio uncertainties was researched. The mass and damping ratio uncertainties were modeled as the structured parametric uncertainty model. An identification method for obtaining the parametric uncertainties was developed by using unbiased least square technique. The instantaneous frequency bandwidth of the external disturbance signals was analyzed by using short time Fourier transform technique. A two loop tracking control strategy that combines the p-synthesis and the disturbance observer （DOB） techniques was proposed. The p-synthesis technique was used to design robust optimal controllers based on structured uncertainty models. By complementing the/z controller, the DOB was applied to further improving the disturbance rejection performance. To evaluate the positioning performance of the proposed control strategy, the comparative experiments were conducted on a prototype micro milling machine among four control schemes： the proposed two-loop tracking control, the single loop μ control, the PID control and the PID with DOB control. The disturbance rejection performances, the root mean square （RMS） tracking errors and the performance robustness of different control schemes were studied. The results reveal that the proposed control scheme has the best positioning performance. It reduces the maximal errors caused by disturbance forces such as friction force by 60% and the RMS errors by 63.4% compared with the PID control. Compared to PID with DOB control, it reduces the RMS errors by 29.6%.展开更多
An automated approach is proposed for a microassembly task, which is to insert a 10 μm diameter glass tube into a 12 μm diameter hole in a silicon substrate, and bond them together with ultraviolet （UV） curable ad...An automated approach is proposed for a microassembly task, which is to insert a 10 μm diameter glass tube into a 12 μm diameter hole in a silicon substrate, and bond them together with ultraviolet （UV） curable adhesive. Two three-degree-of-freedom micromanipulators axe used to move the glass tube and the dispensing needle, respectively. Visual feedback is provided by an optical microscope. The angle of the microscope axis is precisely calibrated using an autofocus strategy. Robust image segmentation method and feature extraction algorithm are developed to obtain the features of the hole, the glass tube and the dispensing needle. Visual servo control is employed to achieve accurate aligning for the tube and the hole. Automated adhesive dispensing is used to bond the glass tube and the silicon substrate together after the insertion. On-line monitoring ensures that the diameter of the adhesive spot is within a desired range. Experimental results demonstrate the effectiveness of the proposed strategy.展开更多
A system using microgripper for gluing and adhesive bonding in automatic microassembly was designed, implemented, and tested. The development of system is guided by axiomatic design principle. With a compliant PU micr...A system using microgripper for gluing and adhesive bonding in automatic microassembly was designed, implemented, and tested. The development of system is guided by axiomatic design principle. With a compliant PU microgripper, regional-edge-statistics (RES) algorithm, and PD controller, a visual-servoing system was implemented for gripping micro object, gluing adhesive, and operating adhesive bonding. The RES algorithm estimated and tracked a gripper’s centroid to implement a visual-servoing control in the microassembly operation. The main specifications of the system are: gripping range of 60~80μm, working space of 7mm×5.74mm×15mm, system bandwidth of 15Hz. In the performance test, a copper rod with diameter 60μm was automatically gripped and transported for transferring glue and bonding. The 60μm copper rod was dipped into a glue container and moved, pressed and bonding to a copper rod of 380μm. The amount of binding glue was estimated about 5.7nl.展开更多
Precision motion actuation is a key technology for miniature medical robotics in a variety of applications,such as optical fibre-based diagnosis and intervention tools.Conventional inductive actuation mechanisms are c...Precision motion actuation is a key technology for miniature medical robotics in a variety of applications,such as optical fibre-based diagnosis and intervention tools.Conventional inductive actuation mechanisms are challenging to scale down.Piezoelectric materials offer a scalable,precise,fast and high-force method but at a limited displacement range.In previous work,the combination of piezoelectric beams(benders)with compliant motion translation structures has been shown to be promising for robotic micro-actuation.In this paper,this approach is employed to implement a three degrees of freedom delta robot,suitable for catheter,diagnostic optical fibre and microsurgery tool manipulation.The fabrication process combines additive manufacturing,origami structuring and piezoelectric beam assembly.Closed-loop control is implemented using a new,on-board visual feedback concept.In contrast to typical optical motion systems,the fully internal visual feedback offers system compactness with precise and reliable camera-to-marker geometry definition.By employment of this method,a delta robot with motion accuracy of 7.5μm,resolution of 10μm and 8.1μm precision is demonstrated.The robot is shown to follow a range of programmable trajectories under these specifications,and to compensate for externally applied forces typically expected during microsurgery manipulations.This is the first,to our knowledge,demonstration of micromotion control using internal visual feedback,and it opens up the way for high-resolution compact microrobots.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50905094)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA044204, Grant No. 2009AA044205)China Postdoctoral Science Foundation (Grant No. 20080440378, Grant No. 200902097)
文摘Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials. In 3D SSMEDM process, the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap, instead of the traditional methods that depend on experiential models or intermittent compensation. However, the effects of process parameters on 3D SSMEDM have not been reported up until now. In this study, the emphasis is laid on the effects of pulse duration, peak current, machining polarity, track style, track overlap, and scanning velocity on the 3D SSMEDM performances of machining efficiency, processing status, and surface accuracy. A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon. The experimental results were obtained as follows. Peak current plays a main role in machining efficiency and surface accuracy. Pulse duration affects obviously the stability of discharge state. The material removal rate of cathode processing is about 3/5 of that of anode processing. Compared with direction-parallel path, contour-parallel path is better in counteracting the lateral wear of tool electrode end. Scanning velocity should be selected moderately to avoid electric arc and short. Track overlap should be slightly less than the radius of tool electrode. In addition, a typical 3D micro structure of eye shape was machined based on the optimized process parameters. These results are beneficial to improve machining stability, accuracy, and efficiency in 3D SSMEDM.
基金This project is supported by National Natural Science Foundation of China (No.59835160).
文摘Performance of giant magnetostrictive material (GMM) is introduced. Principleof work, basic structure and key techniques of giant magnetostrictive actuator (GMA) are analyzed.Its dynamic models of magneto-mechanical coupling are established. The structure and principle ofthe pneumatic servo valve and the micro pipe robot with new homemade GMM are presented. Theexperiment is carried out under typical working conditions. The experiment results show that the GMMpneumatic servo valve has wide pressure control characteristics, good linearity, and fast responsespeed. The movement principles of the GMM robot system are reliably feasible and its maximal movingspeed is about 8 mm/s. It is preferable to the driving frequency of the robot within 100 approx 300Hz.
文摘An experimental study of micro-tool servo with electrostrictive actuator is presented.The design methods as well as the performance of the entire mechanism is given out.The results of the experiment show that the resolution of the micro-tool servo is 0.02μm and the frequency response is up to 200Hz,which satisfies the requirements of the ultra-precision machining.
基金supported by National Natural Science Foundation of China (No.60873032)National High Technology Research and Development Program of China (863 Program) (No.2008AA8041302)
文摘This paper presents an improved support vector machine （SVM） algorithm, which employs invariant moments-based edge extraction to obtain feature attribute. A heuristic attribute reduction algorithm based on rough set＇s discernible matrix is proposed to identify and classify micro-targets. To avoid the complicated calibration for intrinsic parameters of camera, an improved Broyden＇s method is proposed to estimate the image Jacobian matrix which employs Chebyshev polynomial to construct a cost function to approximate the optimization value. Finally, a visual controller is designed for a robotic micromanipulation system. The experiment results of micro-parts assembly show that the proposed methods and algorithms are effective and feasible.
文摘为解决YB95A条外透明纸包装机在透明纸展开切割和传送过程中出现透明纸偏移、长度变化等问题，借鉴YB917条外透明纸包装机的透明纸传送原理，通过增加伺服电机、传感器、编码器和电控程序等，将YB95A条外透明纸传送由主传动驱动改为伺服控制的独立传送，将独立传送装置的电控部分融于MICROⅡ控制系统，控制程序加入到MICROⅡ控制软件中，通过调整IPC（Industrial Personal Computer）的相关参数对透明纸长度和搭口位置进行调整。结果表明，透明纸传送误差由±2mm降低到±0．5mm，实现了透明纸切割长度、传送位置的自动调整；条烟废品率由20～25条／d减少到0～2条／d，有效提高了卷烟包装品质。改进后YB95A条外透明纸包装机适用于彩膜包装，满足了现代卷烟企业对包装材料多样化的需求。
基金Project(50875257) supported by the National Natural Science Foundation of China
文摘The quality of the micro-mechanical machining outcome depends significantly on the tracking performance of the miniaturized linear motor drive precision stage. The tracking behavior of a direct drive design is prone to uncertainties such as model parameter variations and disturbances. Robust optimal tracking controller design for this kind of precision stages with mass and damping ratio uncertainties was researched. The mass and damping ratio uncertainties were modeled as the structured parametric uncertainty model. An identification method for obtaining the parametric uncertainties was developed by using unbiased least square technique. The instantaneous frequency bandwidth of the external disturbance signals was analyzed by using short time Fourier transform technique. A two loop tracking control strategy that combines the p-synthesis and the disturbance observer （DOB） techniques was proposed. The p-synthesis technique was used to design robust optimal controllers based on structured uncertainty models. By complementing the/z controller, the DOB was applied to further improving the disturbance rejection performance. To evaluate the positioning performance of the proposed control strategy, the comparative experiments were conducted on a prototype micro milling machine among four control schemes： the proposed two-loop tracking control, the single loop μ control, the PID control and the PID with DOB control. The disturbance rejection performances, the root mean square （RMS） tracking errors and the performance robustness of different control schemes were studied. The results reveal that the proposed control scheme has the best positioning performance. It reduces the maximal errors caused by disturbance forces such as friction force by 60% and the RMS errors by 63.4% compared with the PID control. Compared to PID with DOB control, it reduces the RMS errors by 29.6%.
基金supported by National Natural Science Foundation of China under(Nos.61227804 and 61105036)
文摘An automated approach is proposed for a microassembly task, which is to insert a 10 μm diameter glass tube into a 12 μm diameter hole in a silicon substrate, and bond them together with ultraviolet （UV） curable adhesive. Two three-degree-of-freedom micromanipulators axe used to move the glass tube and the dispensing needle, respectively. Visual feedback is provided by an optical microscope. The angle of the microscope axis is precisely calibrated using an autofocus strategy. Robust image segmentation method and feature extraction algorithm are developed to obtain the features of the hole, the glass tube and the dispensing needle. Visual servo control is employed to achieve accurate aligning for the tube and the hole. Automated adhesive dispensing is used to bond the glass tube and the silicon substrate together after the insertion. On-line monitoring ensures that the diameter of the adhesive spot is within a desired range. Experimental results demonstrate the effectiveness of the proposed strategy.
文摘A system using microgripper for gluing and adhesive bonding in automatic microassembly was designed, implemented, and tested. The development of system is guided by axiomatic design principle. With a compliant PU microgripper, regional-edge-statistics (RES) algorithm, and PD controller, a visual-servoing system was implemented for gripping micro object, gluing adhesive, and operating adhesive bonding. The RES algorithm estimated and tracked a gripper’s centroid to implement a visual-servoing control in the microassembly operation. The main specifications of the system are: gripping range of 60~80μm, working space of 7mm×5.74mm×15mm, system bandwidth of 15Hz. In the performance test, a copper rod with diameter 60μm was automatically gripped and transported for transferring glue and bonding. The 60μm copper rod was dipped into a glue container and moved, pressed and bonding to a copper rod of 380μm. The amount of binding glue was estimated about 5.7nl.
基金financially supported in part by the Engineering and Physical Sciences Research Council(EPSRC),United Kingdom(EP/P012779,Micro-Robotics for Surgery).
文摘Precision motion actuation is a key technology for miniature medical robotics in a variety of applications,such as optical fibre-based diagnosis and intervention tools.Conventional inductive actuation mechanisms are challenging to scale down.Piezoelectric materials offer a scalable,precise,fast and high-force method but at a limited displacement range.In previous work,the combination of piezoelectric beams(benders)with compliant motion translation structures has been shown to be promising for robotic micro-actuation.In this paper,this approach is employed to implement a three degrees of freedom delta robot,suitable for catheter,diagnostic optical fibre and microsurgery tool manipulation.The fabrication process combines additive manufacturing,origami structuring and piezoelectric beam assembly.Closed-loop control is implemented using a new,on-board visual feedback concept.In contrast to typical optical motion systems,the fully internal visual feedback offers system compactness with precise and reliable camera-to-marker geometry definition.By employment of this method,a delta robot with motion accuracy of 7.5μm,resolution of 10μm and 8.1μm precision is demonstrated.The robot is shown to follow a range of programmable trajectories under these specifications,and to compensate for externally applied forces typically expected during microsurgery manipulations.This is the first,to our knowledge,demonstration of micromotion control using internal visual feedback,and it opens up the way for high-resolution compact microrobots.
