A Novel Architecture for Compiled-type Software CNC System

Transcription

1 Key Engineering Materials Online: ISSN: , ol. 339, doi: /.scientific.net/kem rans ech Pulications, Sitzerland A Novel Architecture for Coiled-tye Softare CNC Y.X. Yao 1, a and S.Z. Yu 1, 1 School of Mechatronics Engineering, Harin Institute of echnology, Harin , China a yxyao@hit.edu.cn, foretyusz@163.co Keyords: CNC, Coiled-tye, Real-tie, Oen syste, Architecture Astract. PC-ased softare couter nuerical control (CNC) syste is the ideal for oen CNC syste, ut there are soe roles aout the current oen CNC syste, such as the liitation of interolation cycle, deanding on high-seed and high recision achining and the liitation of oeration syste (OS). So advances a novel PC-ased architecture for coiled-tye softare CNC syste, in the architecture, the general Windos is adoted as CNC latfor and adots to huge eories acting as data uffer to solve real tie role. And then analyzes the structure and asic rincile of coiling syste. he hardare has een develoed ased on this architecture and alied in the CNC syste. Introduction No, ith the develoent of anufacture technology, any achine tool uilders and end-users are execting that CNC syste can integrate ith uer intelligent function of anufacture syste and oen the lack-ox of CNC, and can ut their on ideas of roduct design and anageent, secial rocess technology and oeration technique into CNC, so it is a trend that CNC syste develos fro a closed architecture and rorietary syste to an oen and general syste. Soe oen CNC syste has een develoed at resent, there are ainly three styles. he first is PC eedded in the CNC syste and only erfors huan achine interface (HMI) and rograing edit tasks, CNC kernel is rorietary. Next, a card added into PC erfors the CNC kernel task such as coordinate axes otion control. his CNC is artly oen on HMI and rograing edits function ased on PC. he third is softare CNC syste (Soft CNC), hich is highest in the level of oenness and the key of study on oen CNC syste Prole of the current Oen CNC syste. In the folloing, e ainly analyze the role of PC-Based softare CNC at resent, ecause the first and second are not oen at strictly seaking. he Contradiction eteen the Liitation of Interolation Cycle and Deand on High-seed and High Precision Machining Figure 1 shos a exale of saled-data line interolation, the next is the relation eteen interolation error and interolation cycle. Interolation cycle is: 60 4 δ ( 2 r δ ) = (1) 1000 F ecause of δ r, then interolation error is: F 18 r 2 δ = (2) in Eq.1 and Eq.2, is interolation cycle (s),f is cutting seed(/in),r is curvature radius on the interolation oint here the curve is interolated (),δ is interolation error (). Fro Eq.1, e can conclude that hen cutting seed is constant, if ant to irove the cutting recision, ust shorten interolation cycle. Also fro Eq.2, hen interolation cycle is constant, the cutting seed is higher, then the interolation error is greater, and then the cutting recision is loer. All rights reserved. No art of contents of this aer ay e reroduced or transitted in any for or y any eans ithout the ritten erission of rans ech Pulications,.tt.net. (# , Pennsylvania State University, University Park, USA-16/09/16,05:23:05)

2 Key Engineering Materials ol Fig.1 Interolation error scheatic It is suosed that δ is and F is 30/in hich coes u to the standard of high-seed achining as required, hen rocess sall curvature radius contour such as r < 15, the < 219us couted fro Eq.1, naely interolation cycle should not e greater than 219μs. It is difficult for the existing PC-ased softare CNC syste to otain this interolation cycle, so the erforance of PC hardare and softare ust e iroved. So if the sae high recision is achieved, the solution is that have to decrease the cutting seed, hich ay restrict soe erforance exertion of high-seed achining tool. And also, ith the advanceent of high-seed and high recision achining, this contradiction ill e ore ovious. he Contradiction eteen Universality and Real-tie aout OS It is necessary that select an oenness, general and flexile OS to ileent the PC-ased softare CNC function, and also OS ust fulfill the strong real-tie requireent of CNC kernel. here are any OS alied in the PC-ased softare CNC syste, such as DOS, Linux +R-Linux and Windos N + RX etc. DOS can e chosen as the latfor of CNC ecause of it s real-tie erforance, ut it has such any shortcoings including single task OS and ad HMI. R-Linux is also real tie OS (ROS), ut CNC syste ased on R-Linux can t e integrated ith CAD/CAM syste that e develoed on Windos OS, hich only exchange data ith CAD/CAM y off-line ode. Windos has any advantages such as good HMI, easy oeration, ealth resource and easy exloitation.etc, so it is favorale for any researchers. But, general Windos is non-real tie OS. No it is a solution for the contradiction eteen universality and real-tie that real-tie kernel such as RX is extended into Windo N or Windos, the extended real-tie kernel can reach icrosecond interolation cycle. Hoever, the rice of the extended real-tie kernel is very high and increases the cost of CNC syste. herefore, it is ideal solution for the role that alying Windos OS y the silest and roer ethod as PC-ased softare CNC latfor. he Architecture and Analysis of Coiled-tye Softare CNC he architecture of coiled-tye softare CNC syste is shon in Fig.2, in this architecture, anual achining rogra, the rogra fro autoatic rograing syste, the design data fro CAD/CAM, self-defined track function and soft PLC can e easily inut into CNC syste ith convenient HMI in PC. After these rogra or data are fully coiled y coiling syste, they are translated into the target-code that e coosed of dislaceent of coordinate axis direction, dislaceent offset and sitching value, also the target-code files, hich size is deterined y the size of otto large eory, can e created, and then target-code files ake u of target-code files lirary. transitted control and check syste transits the target-code ased on target-code files to otto syste through us-astering syste. Access eory controller accets the code and stores the code into huge eory 1 or 2 alternately. Position and I/O control rocessor also reads the code data through access eory controller fro huge eory 1 or 2 alternately and sequentially, and controls the otors and sitching coonents to execute relevant action. So CNC finishes the hole achining task ste y ste through accessing the target code sequentially. he Structure and Basic Princile of Coiling. raditional CNC executes rogra ased on the unit on rogra segent, interrets a segent, executes a segent and loos until ending the achining rocess, hich is the sae as BASIC language interrets and executes its sentence, hich is naed interreting-tye running ode. Another is naed coiling-tye running ode. In this ode, anual achining rogra, the rogra fro autoatic rograing syste, the design data fro CAD/CAM, self-defined track function and soft PLC are fully coiled efore achining, then are translated into the original

3 444 Progress of Precision Engineering and Nano echnology target-code that e coosed of dislaceent of coordinate axis direction, dislaceent offset and sitching value. In the original target code converted function, the dislaceent and dislaceent offset in the original target code are converted into the D/A digit value. After eing added into start check code and end check code, the target codes are raed to data files hich e saved into hard disk, and every data file size is deterined y a huge eory size. his target code in the data files can e executed y the osition and I/O control rocessor directly, hich silicities the rocess of data rocessing of rocessor and increases the efficiency. he structure of coiling syste is shon in Fig.3, different inut tye has different rocessing flo, ut generates the sae target code. Manual Machining Progra Autoatic Prograing CAD/CAM Self-defined rack Coiling arget File 1 arget File n ransitted Control and Check Bus-astering Soft PLC Files Lirary Huge Meory 1 Huge Meory 2 PC-ased Access Meory Controller Servootor elocity Control, Current Control and Poer Alifier Position and I/O control rocessor Position Detection Aaratus Sitching Coonents Fig.2 he Architecture of Coiled-tye Softare CNC syste Manual Machining Progra Autoatic Prograing CAD/CAM Self-defined rack Soft PLC Encoding Interret ool rack Generation Encoding ools Coensation Data Calculation Seed Process Post Process ier Process Interolation Calculation Fig. 3 he Structure of Coiling arget ransforation Add Check Wra arget arget Files he data structure of every target code is defined as folloing. tyedef struct Data{ int startcode; int X1; int X1; int Xn; int Xn; char O1; char O; int endcode; }; Where Xn is the dislaceent of n coordinate axis; Xn is the dislaceent offset of n coordinate axis. O is the sitching value of sitch coonent; the value is 0 or 1. startcode is start check code; endcode is end check code. So the size of every target code is n * * 2 yte. If huge eory size is S Myte, then the nuer N of target code in a eory is: 6 S * 10 = n * N (3) 4 * 2

4 Key Engineering Materials ol he Solution for Real-tie Prole in Non-real ie OS. At first, syste has to huge eories that act as data uffer eteen PC and rocessor, as shon in Fig.4. At the eginning of achining, target code coiled is first stored into the huge eory 1, hen the huge eory 1 is full, access eory controller sitches riting oeration fro 1 to the huge eory 2 so that PC can continue to store data into eory 2, at the sae tie, access eory controller sitches reading oeration to eory 1, so rocessor can read data fro eory 1 and then executes the relevant action according to target code. But once the huge eory 1 is ety, PC stores data into eory 2 and rocessor read fro eory1, rocess aove is going on alternately until finishing the all achining. Writing oeration of PC is indeendent of reading oeration of rocessor in the rocess, so it avoids to conflict that oth access the sae eory. As long as the tie that sent y PC riting a eory fully is enough shorter than the total tie that sent y PC eing in resonse to a eory etily and y rocessor rocessing a eory, CNC achining can go on staly. PC syste Access Meory controller Huge Meory 1 Access Meory controller Huge Meory 2 Position an I/O Control Processor Fig.3 Access o Huge Meory Alternately For exale, (s)is single axis osition control cycle in rocessor ( single interolation cycle), (Myte/s) is us seed, (Myte/s) is average seed of access eory controller, d (s) is total tie of PC resonse tie, accessing disk file tie and rocessing rogra tie in PC, dd (s) is tie of rocessor rocessing a target code, (s) is the tie of PC riting a huge eory fully, and then, S S = + + d (4) r (s) is the tie of rocessor reading a eory etily, and fro Eq.3, 6 S S *10 S r = * * + + d d * = ( * + d d ) * + n *4+ + 4*2 N n N n (5) If the PC us is PCI, is 20Myte/s, is 40Myte/s,s is 256M and syste can control 20 otion axes and 1000 sitching value, at the sae tie, syste adots DSP as rocessor hich frequency is 20Mhz, dd is 500μs and single interolation cycle is 20μs, then fro Eq.5 r is 218s, and fro Eq.4 is 198s, and that as long as the resonse tie of OS in PC is shorter than 100s, CNC syste can ork roerly and staly, ut this resonse tie is no role for Windos, hen single interolation cycle is u to 20μs. herefore, even if Windos is non-real tie OS, it still can e used as PC-ased softare CNC latfor ith the aove structure. Alication Exale Hardare structure develoed is shon in Figure 5, it adots PCI us as counication ode eteen PC and osition and I/O control rocessor, DSP ith 16 it is chosen as osition and I/O control rocessor. Access eory controller is designed and develoed y FPGA technology, and huge eory is vendor-neutral SDRAM stri so as to eing changed and configured easily. Besides, e add doule ort RAM (DPRAM) to hardare structure to act as shared uffer, soe inforation such as DSP configured data, araeter defined, soe secial instruction and sot status etc., can e exchanged eteen PC and DSP. Also it adots current vendor-neutral otor servo driver to ileent elocity Control, Current Control and Poer Alifier.

5 446 Progress of Precision Engineering and Nano echnology At resent, e have develoed this hardare, hich is shon in Fig.6, ith the hardare, the PC-ased softare CNC syste is eing develoed. In this syste, Windos 2000 OS is adoted. Fig.5 Hardare Structure Fig.6 he Control Card Develoed Suary PC-ased softare CNC syste is the ideal for oen CNC syste and also the key of study on oen CNC syste, ith the advanceent of high-seed and high recision achining, required interolation cycle is shorter and shorter, oreover general OS such as Windos is ideal OS for CNC syste ut it is not real tie OS and cannot e used as CNC latfor directly. In this aer e roose to adot coiling-tye running ode and to huge eories that act as data uffer eteen PC and rocessor to solve the role aove. hen this aer advances a novel PC-ased architecture for coiled-tye softare CNC syste that adots general Windos as the latfor. As reset, e have develoed hardare ased on this architecture and are studying and develoing deely. References [1] Prischo G and et al: Annals of the CIRP, ol.50 (2001), [2] Chengrui Zhang, Heng Wang and et al: J. Mater. Process. echnol., ol.139 (2003), [3] Katz.R, B.K Min and Z.Pasek: ERC/RMS Reort, (2000), No.35. [4] Y. Koren and et al: Annals of CIRP, ol.43 (1996), [5] Claudio A, Kevin O and et al: IEEE Int Sy on Intelligent Control, ol.27 (2002),.290. [6] Mao Junhong, Li Lichuan and et al: J. Mechanical Engineering, ol.36 (2000), [7] Li Bin and et al: J. Coute in Industry, ol.55 (2004), [8] Liang Hongin, Wang Yongzhang and LiXia: J. CIMS, ol.10 (2004),