MES in vehicle manufacturing - Broadcasting

Vehicle manufacturing is very complicated, it has lot of processes, and lots of them are interactive from each other.

For automation design, it requires lots of data exchange between different stations/areas/devices/lines, normally it’s via point-to-point communication between PLCs.

And MES as a system covering whole plant/most process/most devices, normally it will be acting as backbone of data exchange of most data.

This article will introduce some cases.

 

1.    Lift on at engine sub-assembly lines

The engine assembly consists of 4 assembly lines: interior line, exterior line, cylinder head sub-assembly line, and piston sub-assembly line. Interior line and exterior line are working one after another, and the 2 sub-assembly lines are quite independent.

To work as per Orders, we need to align sequence of sub-assembly lines with main lines.

This is the way to do it:

1)       When MES receives Work Orders from ERP, it will generate sub-orders of sub-assembly lines.

2)       When engine is lift on at interior line head station, MES will broadcast information to head stations of sub-assembly lines: with Work Order, Engine number, part number, engine model.

3)       Sub-assembly lines will lift on based on the data it received.

Please refer to diagram 2.6-1:

Diagram 2.6-1: Engine lift-on broadcast

 

2.    Process parameters preparation

Now most vehicles plants and engine plants require flexible production, that means same line and same devices can support manufacturing of multiple model types.

This requires line-side devices can work flexibly, can work based on process parameters and profiles automatically.

To make sure daily work continuously, MES is required to broadcast related data to line-side devices.

For example in vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES will broadcast these information:

1)       Sends VIN marking data to interior line PLC, and VIN marking system of engine line.

2)       Sends VIN number and model type to Torque Gun system; later when vehicle comes to torque station, Torque Gun system sends torque program to torque controller.

3)       Sends VIN number, model type, attributes, software BOM to vehicle calibration system; later when vehicle comes to working station, calibration system write software to vehicle ECU.

4)       Sends VIN number, model type, attributes to vehicle test system; later when vehicle comes to working station, test system will run test programs with according parameters, to check wheels and lamps and other functions.

 

3.    Assembly sheet printing

In vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES will command printers of sub-assembly lines, to print out assembly sheets.

Assembly sheets are normally A3 or A4 papers, include such information:

1)       Vehicle’s basic data such as VIN number, model type, attributes, color.

2)       Part number, part description, and part barcode label of key parts. Barcode labels are used for error proofing: at key part error proofing stations, worker will scan VIN number, then barcode labels of assembly sheet, then scan vendor’s labels, then MES will check if vendor’s labels are matched with part labels of assembly sheet, if not then raise error.

 

4.    Material Pull

In vehicle Final Assembly Shop, daily production follow JIT(Just In Time) rules, to make sure production is as effective as possible.

Line’s capacity is limited by capacity of workers and machines, the other operations(such as material handling, machine readiness) are supporting them.

The requirement for material handle:

1)       Only store necessary materials to avoid wrong usage.

2)       In case of material shortage, requires supply in time.

Diagram 2.6-2 shows relationship between MES and material handling:

1)       When vehicle travels through key material pull station(such as PBS out, and interior line head), MES will generate vehicle’s travel request based on RFID data, and broadcast to LES(Logistics Execution System).

2)       When LES receives broadcast data, it will cut down storage of line-side material, as they are considered to be consumed soon, and check if it’s smaller than safe storage, if so then trigger a material pull request.

3)       Material handlers will get material from buffer zone or warehouse, and then deliver to assembly line.

Diagram 2.6-2: MES and material handling

 

5.    Material back flush

MES will offer an interface, to broadcast back flush data to ERP.

When vehicle comes out of Welding Shop, Painting Shop, Final Assembly Shop, MES will send out broadcast of VIN number, then ERP will back flash materials of that vehicle.

 

MES in vehicle manufacturing - Route Control

Route Control means based on MES commands, conveyor PLC will decide how to move vehicle forward.

This article will introduce some key route control functions.

1. WBS Route

Vehicle manufacturing has 4 key process: Punch, Welding, Painting, Final Assembly. There’s a WBS buffer zone between Welding Shop and Painting Shop, and a PBS buffer zone between Painting Shop and Final Assembly Shop.

WBS is short of Welded Body Store.

PBS is short of Painted Body Store.

With some painting conditions, if we need to change painting color for next vehicle, then we need to stop machine, and clean, and change oil for it, it will take quite a lot of time. So to reduce machine shut down time and the waste of oil, normally we will schedule the vehicles by same color.

So in WBS area, MES will re-sequence the vehicles by color.

Besides of that, WBS also has functions of:

1) Offers a big buffer zone.

2) Offers a return lane, to return vehicles back to repair.

3) Track vehicle location based on RFID identification.

2. PBS Route

PBS locates between Painting Shop and Final Assembly Shop.

The setup of PBS is based on these requirements:

1) Planners want to align Work Order to Sales Orders.

2) Logistics handlers want some parts delivered by batch in sequence.

3) Production department want to build some model for quite a long time, to reduce operation mistakes.

4) Process department want to balance the lines so workers won’t be tired very soon.

Normally PBS route function is consisted of MES/PLC/HMI/RFID devices, and can be achieved by different methods, such as:

1) MES sends route command by rules automatically..

2) PLC routes by rules automatically.

3) Operators handles by HMI manually.

Diagram 2.5-1 shows an example of PBS route, icon of R stands for an RFID read station:

1) Vehicle leaves Painting Shop, MES collects its travel record, and broadcasts to ERP for back flush.

2) Vehicle comes to PBS In, MES informs conveyor PLC with lane number. Route rule: based on vehicle model.

3) PBS area has a fast lane, 1 return lane, and 4 normal lane. Fast lane is controlled by manually, which allows vehicle come to PBS out directly. Return lane is also controlled by manually, which is used to hold specific vehicles.

4) MES offers route rules such as by minimum VIN number and by model, and informs PLC to move vehicle based on rule. Fox example for minimum VIN number rule, MES will check the minimum VIN of all 4 lanes, and inform PLC to move that vehicle of according lane.

5) Vehicle leaves PBS, and moves along conveyor line, and comes to tear-off-door station, so there’s a sequenced vehicles buffer between PBS Out and tear-off-door station.

 

Diagram 2.5-1: PBS Route

3. Safe Door Control

I’ve introduced Quality Gate in previous article, which controls vehicle moving by using block bar and traffic light.

The same method is also used in Final Assembly Shop, diagram 2.5-2 shows a safe door control process after completing assembly.

1) After completed all assembly, and validated quality good, then vehicle will be driven through Door #1 or #2, forward to Logistics Parking Lot, there the vehicle will be handled by 3rd party company to deliver to car dealer.

2) If a vehicle needs road test, then it will be driven through Door #3, and return back to Final Assembly Shop through Door #4 after test.

3) If a vehicle needs process hold(holding for some time for further quality check), then it will be driven to Process Parking Lot through Door #5, and then drive out through Door #6.

4) Any vehicle with issues found will be driven back to Repair Area through Door #7.

 

Diagram 2.5-2: Safe Door control process

MES in vehicle manufacturing - Quality Management

Quality management is a key function of MES.

This article will introduce some specific functions of quality management in vehicle manufacturing.

1. Defect management

In quality management module, defects are configured as master data.

Scientific definition of defects helps operators to input defects quickly, and it also helps to generate defect analysis report with more values.

Here introduces 2 types of defect definition.

Type 1: grouped by class, such as class level 1/class level2/defect, or shop/line/station/defect.

Type 2: grouped by coordinates. For quality check station, we can load a component picture into system, and system will split it into lots of areas with horizontal and vertical coordinates. When defects are found, operator click the according position of the picture, then MES will find its mapped coordinate and store it into system.

Type 2 is mostly used for appearance check.

Based on the data recorded by coordinates, MES can generate report to highlight the defect density of each area, and then we can adjust our process to improve quality accordingly.

 

Diagram 2.4-1: Input defect based on coordinates

2. Quality route

In vehicle manufacturing, MES is highly integrated with automation systems, even the manual quality check result should interact with conveyor line.

The so-called quality route means to decide vehicle’s route based on quality status. Here we have 3 scenarios.

scenario 1: vehicle quality route.

As shown in diagram 2.4-2:

1) When vehicle comes to quality check station, operator input defect, and then choose a repair lane, the data will be saved into MES. If no defect found, then vehicle will be marked with default lane.

2) When vehicle comes to turn table, PLC identifies vehicle, and then request to get lane number from MES, and then transfer vehicle accordingly: via default lane to next station, or via repair lane to repair area.

 

Diagram 2.4-2: Vehicle quality route

Scenario 2: engine quality route.

Consider that engine is standing still in any assembly station, so we can install RFID reader in any key assembly stations and turn tables.

So in any assembly station or quality check station, operator can input defects, and PLC will write quality status and route number into RFID Tag; when vehicle comes to turn table, PLC reads route number from RFID Tag, and then move engine forward accordingly.

Scenario: product audit.

Normally for audit, we pick audit target based on specific rate, and we don’t want operators to know whether a product requires audit or not.

So, based on audit rate, we can decide which product require audit when generating Work Orders, and write the audit mark into RFID Tag.

When vehicle comes to turn table before audit, PLC reads audit mark from RFID Tag, and then move vehicle accordingly.

3. Quality Gate

Normally we setup Quality Gate after a set of key manufacturing process, such as vehicle’s lift off station of welding/painting/final assembly, and engine’s lift off station of inner line/outer line.

From point of view of quality control, Quality Gate will check if a product has completed process of current area, if yes then allow it to move forward to next process.

Quality Gate will check below quality data if possible:

1) If quality status is good.

2) If completed all key stations.

3) If short build or over build any component.

4) If failed in any test stations.

5) If failed in any audit station.

6) If any defect not cleared.

Based on the check result of Quality Gate, MES will work with PLC, to decide vehicle’s direction, for example: lift up Gate bar so vehicle can drive to parking lot, or lock Gate bar and alarm operator to drive vehicle back to repair area. Its logic is:

1) PLC identify vehicle by RFID.

2) MES check its quality result, and show it together with defects(if have) in TV.

3) MES transfers quality status to PLC, PLC turn on traffic light, and lift up or lock the Gate bar accordingly.

Refer to diagram 2.4-3.

 

Diagram 2.4-3: Quality Gate and Quality bar

MES in vehicle manufacturing - Vehicle Identification

This article introduces the methods of identifying vehicles during manufacturing.

There’re 5 types of material used to identify vehicles:

1) Ultra high frequency RFID Tag, mostly used in vehicle manufacturing.

2) High frequency RFID Tag, mostly used in manufacturing of engine and transmission.

3) Screw/Bolt RFID Tag, mostly used in machining of engine and transmission.

4) Metal 2D barcode, mostly used in machining of engine and transmission.

5) Paper barcode label, mostly used in vehicle manufacturing.

Details are mentioned as below.

1. Ultra High Frequency RFID TAG

Ultra High Frequency RFID Tag is referring to RFID Tag which works in frequency range of: 65 - 868 MHz(Europe), and 902 - 928 MHz(North America). 

RFID is short of Radio Frequency Identification.

Tag is the material used to store data.

RFID related devices include: 

1) Tag, used to store data.

2) Antenna, used to expand covering area of radio frequency signal.

3) Reader, used to write data to Tag, and read data from Tag, and send energy to activate Tag.

4) Communication module, used to transfer data between Tag and PLC data block.

5) PLC or PC as data receiver.

6) Other devices, such as cable, connector.

Diagram 2.3-1 shows relationship between RFID related devices:

 

Diagram 2.3-1: Relationship of RFID related devices

The advantage of Ultra High Frequency RFID is its high range of identification area, which can reach a couple of meters.

In vehicle assembly shop, a typical station has 6 meters, and vehicle is moving slowly during reading, Ultra High Frequency RFID can support such requirement from distance and angle.

Now let me introduce some working scenarios.

Scenario 1: Merge station of Welding Shop

When vehicle’s sub-assembled parts come from Front Cabinet/Front Floor/End Floor, and move forward into merge station, PLC will download new Work Order and VIN number of new vehicle, together with information such as model type, color, vehicle attributes, and then PLC writes data into RFID Tag.

Scenario 2: Quality Check station

There will be a RFID station before Quality Check, and another RFID station after Quality Check, after receiving data from PLC and RFID Tag, MES will know the vehicle list which have already passed previous RFID station, but not yet passed later RFID station, so in Quality Check station, MES will display this list, and operator can pick one from it.

Scenario 3:: Material trigger station in Assembly Shop

Normally there will be a RFID station in PBS OUT, so when vehicle passed this station, MES will broadcast vehicle number to logistics handling/execution system, to trigger the pull of material for assembly lines.

2. High Frequency RFID TAG

High frequency RFID works in 13.56 MHz, its read/write distance is less than 0.2 meter.

Due to this limitation, the application of RFID should match with below conditions:

1) Tag should be holding still during reading/writing.

2) Tag should be near Reader as close as possible.

Such technology is used in assembly of engine and transmission quite a lot, because their manufacturing process can match with these 2 conditions.

For example, when the engine comes to an assembly station, it will be holding still on the pallet, and RFID Reader is installed just below pallet, and RFID Tag is plugged into pallet just above Reader.

The feature of this type of RFID makes it quite different to identify an engine than the way to identify a vehicle.

1) Uses High Frequency RFID.

2) A Reader is installed in each station, while in vehicle assembly Readers are only installed in line head and line end stations.

Since each station has installed RFID Reader, it’s reasonable to store process data into RFID Tag as much as possible, so we can read and write RFID Tag directly, without interacting with MES for each station.

For example, Siemens High Frequency RFID Tag can store up to 54KB data, then we can store lots of data into it, such as product master data, lift on data, BOM, key working command, key process parameters, assembled part Serial Numbers, traceability data, repair data, so a Tag can be regarded as a working manual and also as an assembly dataset.

3. Screw/Bolt RFID TAG

The key part of an RFID Tag is its data storage chip, which can be packed and installed with many ways.

Some Tags are packed with magnet together, so we can stick it at top of vehicle; So Tags are packed as coin-thick plate, so we can plug it into pallet.

Here introduces screw form Tag, such as Siemens RF630T, this Tag is packed with a M6 screw and a 64B data chip, can be installed into M6 holes. Balluff’s screw form RFID Tag can store data up to 64KB.

This kind of Tag can be used in 2 typical scenarios.

Scenario 1: machining of engine and transmission.

In Machining Shop, we don’t have pallet, the mechanical parts are moved between stations by robots, so we can only install Tag into mechanical parts, and move together with it.

Scenario 2: Assembly of engine and transmission.

Although we do have pallet in assembly, but some company want to keep key manufacturing data in RFID Tag, and ship it to customers as part of product, so in the future if we need to repair it, we can read original manufacturing data from RFID Tag.

4. Metal 2D barcode

In machining shop of engine and transmission, to avoid infection of bad environment, normally laser marking is used to generate 2D barcode in surface of metal part.

The machine used to generate metal 2D barcode is called laser marker, it consists of laser transmitter, control module, positioning module, communication module.

Metal 2D barcode cannot be identified by normal handhold barcode scanner, it needs specific device for identification, it consists of photo taking, image processing, OCR, and communication modules.

5. Barcode label

Barcode labels have been used in MES field all the time, especially in vehicle manufacturing.

Barcode labels have these outstanding advantages:

1) Very cheap.

2) Can be read by man eyes.

3) Don’t require interaction with backend system(PC regards scanner as keyboard device).

Now let me introduce 2 typical scenarios.

Scenario 1: Assembly sheet printing

When vehicle passed through PBS, MES will trigger all sub-assembly line printers to print out assembly sheet of each line, the sheet includes lots of barcode labels, such as of VIN number, model type, key station part numbers. When vehicle comes to assembly station, operator will scan labels of part on stack, and also of label of part in sheet, then MES will validate if they are matched or not.

Scenario 2: Error Proofing.

When a vehicle is started assembly, MES will print out an Error Proofing sheet, which is a list of barcode labels, each label is the parameter string of each key Error Proofing station. When vehicle comes to Error Proofing station, operator scans Error Proofing label, and then device PLC gets parameters from label.

MES in vehicle manufacturing - Welding & Order Release

Normally vehicle manufacturing is scheduled by Work Orders.

There’s a term OTD(Order To Delivery), means the whole process from creating Sales Order to delivering product.

Based on customer request, market investigation and forecast, shop dealer create Sales Order in car maker’s sales system.

Sales system will bind the information with market strategy, then release Sales Order.

Then Sales Order is loaded into plant’s ERP system, which will check with plant calendar/machine status/material storage/purchase plan, then run MRP/APS, and create daily Work Order for it.

And then SRM system will generate component delivery request, and send it to vendors.

After vehicle is built, it will be transported to dealer.

Diagram 2.2-1 shows OTD flow:

 

Diagram 2.2-1: OTD flow

Normally for process of punching, welding, painting, and assembly, each process costs 1 day for manufacturing, and then costs a couple of days for transporting. ERP will base on Sales Order to generate Work Orders of Assembly Shop, then create Work Orders of other 3 shops accordingly.

ERP Work Orders have the vehicle data such as model type, they also show the building sequence of each day.

But in Punch Shop, because it uses batch build model, it will not follow the Work Order sequence strictly.

In Welding Shop, MES downloads ERP Work Orders, and generate daily MES Work Orders. In MES, planners can lock/freeze/re-sequence these Work Orders, so the final sequence could be different than original sequence.

After completing welding, vehicles come into Paint Shop through WBS, these vehicles can be re-sequenced according to WBS routing rules.

After complaint painting, vehicles come into Assembly Shop through PBS, based on PBS routing rules, normally vehicles will be re-sequenced based on model type, VIN numbers, etc.

Normally only Welding Shop’s Work Order sequence is highly aligned with ERP planning.

In Welding Shop, MES needs to accomplish these planning functions:

1) Download Work Orders from ERP automatically.

2) Lock, freeze, re-sequence Work Orders.

3) Validate Work Order, such as to check process readiness.

4) Send Work Orders into PLCs of main line and sub-assembly lines.

5) Broadcast Work Orders to later stations.

As showed in diagram 2.2-2:

1) MES releases Orders into stations of Front Floor, Back Floor, Front Cabinet, and SL010/SR010/SL070/SR070 of Main line.

2) In UB010 merge station, PLC will check if the components from 3 sub-assembly are matched, if so then generate VIN number for it.

3) When vehicle comes to main line, PLC will check if it matches with components from sub-assembly lines, if not then get component from buffer zone.

 

Diagram2.2-2: Order release in Welding Shop

At Work Order downloading stations, device PLC downloads Work Order data from MES, including: Sales Order, Work Order, VIN number, model type, vehicle attributes, etc. The key data will be written into RFID Tag in merging station.

As off-line buffer, normally PLC will buffer Order data of 3~10 vehicles.

MES in Vehicle Manufacturing - Punch & PMC

Building a vehicle requires lots of money. To develop a new type of vehicle, almost needs 500 million RMB for development and 2 billion RMB for manufacturing. Development cost include: model design, prototyping, process design, component design, vehicle calibration, vehicle testing, component testing. Manufacturing cost include: facility building, device buying and setup, production preparation. During manufacturing cost, device buying and setup take almost 3/4, and Punch Shop takes 35% of device cost in whole plant. Suppose one type of vehicle is very welcomed by customers, its sales number is beyond plant’s building capacity, in that case, is it possible to expand plant and buy more devices to build more vehicles? From point of view of Punch Shop, it’s very difficult. Because punch machine has very high requirement to ground flatness and stability, so it’ll take very long time to build punch facility. Besides that, punch models also need long time to build. So in order to improve plant capacity, it’s most likely to use current devices effectively as possible. Punch process includes: Unpack, get material, transfer material, positioning, feed material, cleaning, punch, test. Most processes are done by punch machine automatically, operators assist machine accordingly. So, production and devices and systems need to support devices: - Operators need to assist devices to ensure daily work continuously. - Device engineers need to maintain devices, and fix problems ASAP. - Systems need to find out any errors or alerts, and to notify engineers accordingly. So in Punch Shop, the main functions of MES is PMC. PMS is short of Production Monitoring and Control, in MES field, it’s focus on devices. PMC collects below information: 1) Devices’ running state. 2) Device abnormal information, such as alert code, error code. 3) Number counters, such as shift production counter, buffer zone counter. 4) Time counters, such as accumulated down time. 5) Devices’ key process parameters. 6) Working-in-process product information, such as serial number, material number, model type. 7) Production rate information, such as assembly time, waiting time, blocked time. 8) Line speed. Technically speaking, MES is mainly collecting device data via PLC. PLC is short of Programmable Logic Controller, is the logic layer and application interface of devices. PLC stores PMC related business data into specific Data Blocks, and then MES get data from PLC via OPC. OPC is short of OLE for Process Control, can map PLC data into OPC Server memory tags. MES communicates with OPC via OPC client or IIoT gateway. Below diagram shows PMC data flow:

Diagram 2.1-1: PMC Data Flow We can see that, after OPC collected devices data from PLC, it uses data for 2 purpose: 1) OPC sends data to SCADA Server, and then output data in real time via SCADA client. 2) OPC sends data to MES Server, archives in Database, then outputs as report. In lineside, operators and engineers are checking real time data. SCADA is short of Supervisory Control And Data Acquisition. Production department can monitor and control devices remotely, and IT uses SCADA for collecting and displaying data. Popular SCADA products include: Siemens WinCC, Rockwell FTView, GE Cimplicity. SCADA server can synchronize data from OPC server quickly, its rate frequency is 250ms~1000ms, and then SCADA client gets data from SCADA Server, and then output data into TV or LED board.

沃尔沃ANDON系统介绍

沃尔沃是知名的豪华乘用车品牌制造商，它的工厂特点是：

- 质量标准高

- 单车利润高

- 车型少

- 生产节拍慢

ANDON呼叫系统是沃尔沃的核心车间管理系统，体现了沃尔沃质量第一、零缺陷的生产管理理念。当现场出现质量问题时，ANDON系统会自动通知生产线停线，直到问题解决。

1. 业务功能

沃尔沃工厂的应用系统由3个层次组成。

第1层是核心的生产执行系统，包括：

- GOB计划执行系统，相当于其它整车厂的MES。

- ANDON呼叫管理系统，集成了PMC设备监控、ANDON呼叫、AVI车辆识别、EPS防错功能。

- ATACQ质量执行系统。

- XPS零件追溯系统。

- SJC拧紧管理系统。

- VCATS车辆配置与检测系统。

- VD设备层接口

第2层是外围的工厂系统，包括：

- ARO订单管理系统。

- OHF计划管理系统。

- BIS车辆属性配置系统。

- CMP物料计划管理系统。

- PLUS库存管理系统。

- CHIMAS物料拉动系统。

- SBS工艺节拍平衡。

- API设备管理系统。

第3层是部署在集团的系统，包括：

- HERCULES销售商系统。

- PIE车载软件系统。

- QW90质量分析系统。

ANDON系统的功能主要包括：

1) 设备监控。

ANDON系统通过与线体PLC集成，从PLC采集设备运行状态、报警信息、故障信息、计划执行情况、车辆队列、产量、停线时间等。

2) 异常呼叫。

ANDON系统通过与拉绳、按钮、设备的集成，提供人工质量呼叫、人工物料呼叫、设备自动呼叫等呼叫方式，并通过柱灯、音箱、大屏等方式通知到责任人员。现场ANDON大屏同时也集成PMC的部分关键数据。

3) 车辆识别。

ANDON系统通过与RFID阅读器的集成，获取车辆VIN号，并从GOB系统获取车辆配置信息。

4) 防错集成。

在总装车间，ANDON PLC集成了RFID阅读器、编码器、传感器，从而通过计算得到车辆在流水线上的实时位置，为拧紧、打刻、加注、涂胶、试漏等工位提供车辆VIN号、车辆属性、工艺参数信息，用于指导设备进行操作；当作业完成后，设备PLC会向ANDON PLC发送作业结果和关键数据；如果作业失败，ANDON PLC会通知线体PLC停线。

2. 架构特点

图3.4-1是沃尔沃ANDON系统的架构示意图：

 

图3.4-1 沃尔沃ANDON系统架构

架构要点：

1) 在车间现场配置ANDON PLC，作为现场控制器。

由于业务逻辑复杂、兼容程序多、代码容量大，采用西门子WINAC作为主控PLC。WINAC是特殊的工业PC，使用WINDOWS操作系统，然后安装软PLC软件，组态到网络中后，在编程和使用上和硬件PLC没有区别。

2) ANDON PLC集成了RFID阅读器、编码器、传感器、拉绳、按钮、柱灯、播放器等现场硬件设施。

3) ANDON PLC通过VD实现和线体PLC、设备PLC、ANDON服务器、GOB服务器的通信。

VD是沃尔沃自己开发的一个现场通信层，能够实现和应用系统、OPC、PLC、拧紧枪控制器等系统和设备的通信。

4) ANDON服务器驱动现场ANDON大屏的显示画面。

5) 实时通信，参与现场控制，当防错失败时，会通知线体停线。

3. 架构优点

1) 可移植性好。PMC、ANDON、AVI、EPS等相关业务模块的代码经过封装，容易移植到新的项目。

2) 硬件、网络、画面等规范一致，采购和实施周期得到控制。

3) WINAC能够通过硬盘缓存大量的数据，因此防错需要的工艺参数可以提前从应用系统获取，以减少控制系统和应用系统的耦合性。

4. 架构缺点

1) 单个项目的PLC设备多，成本高。

2) 业务逻辑复杂，难理解。

3) 冗余代码多，由于要兼容旧版本的设计，PLC程序包里包含大量的各类设备控制程序。

4) 程序逻辑复杂，最核心的呼叫处理程序，包含了188个程序段和76个外部参数，引用时非常困难。

5) 由于采用WINAC，可靠性比硬件PLC差。

福特NGAVS介绍

作为第一个将流水线技术引入汽车工厂的汽车制造商，福特一直以来非常注意自动化技术的应用，而NGAVS等系统，就充分利用了IT相关技术，实现了业务系统和控制系统的高度集成。

1. 业务功能

NGAVS即Next Generation Automatic Vehicle Scheduling，即下一代自动车辆调度系统。

NGAVS主要实现以下业务功能：

1) 焊装车间计划的下发。系统自动将计划下发给发动机舱、前地板、后地板、左侧围、右侧围的线体PLC，PLC根据NGAVS队列执行抓料、焊接等作业。

2) 车型识别。PLC从RFID TAG读取VIN号，然后从NGAVS查询得到对应的车型信息。

3) 过站记录。PLC完成装配作业后，将VIN号和过站标识发送给NGAVS，NGAVS处理后转发给ERP系统(用于物料结算)和物流系统(用于物料拉动)。

4) 防错集成。在总装车间装配线的线头安装RFID阅读器，识别车辆后由NGAVS转发给防错系统，用于计算流水线上车辆的队列和实时位置，作为防错系统的计算依据。

5) 质量检查站集成。在质量检查站的前、后工位安装RFID站，NGAVS查询哪些车辆已经通过前一站尚未通过后一站，把符合条件的车辆队列转发给质量检查站，这样工人无需手动扫描VIN号就可以识别车辆。

6) 拉入拉出。通常在质量检查站后一站紧接着设置拉入拉出站。拉出是把存在质量缺陷或特殊标记的车辆从生产线上移除，用于判定、维修，从而不影响主线的正常作业。拉入是指将已离线的车辆，经维修等操作后重新送回主线。拉入拉出操作会更新主线的车辆队列，从而影响分装线的零件配套和物料的配送需求。

7) 质量门。在焊、涂、总三个车间的车辆移交点设置质量门，并通过PLC和升降梯集成。如在焊装车间，NGAVS通过RFID识别车辆，并查询得到其质量状态；对于正常车辆，通知PLC将其通过升降梯送入WBS；对于异常车辆，通知PLC将其送入维修区。

8) 安全门。在总装车间出口设置安全门，并通过和道闸集成，根据车辆的VIN号，查询得到车辆的质量状态、工单状态等，从而判断是否允许车辆进入商品车停车场、工艺停车场、路试区域。

由于历史原因，福特的工厂制造系统非常多，每个系统都有特定的应用领域，如：

- FIS, Factory Information System工厂信息系统，相当于其它整车厂的PMC系统，主要通过采取现场PLC数据，来实现对生产现场的监控，并通过车间大屏进行展示。

- EP, Error Proofing防错系统，提供拧紧防错、料架防错、加注涂胶打刻防错等。

- CDC II, Component Data Collection II零件数据采集系统，即通过扫描枪来采集零件的原始供应商序列号信息，主要用于追溯和召回。

- QLS VO, Quality Leadership System for Vehicle Operation整车质量领先系统，通过缺陷管理和分析来提升质量控制。

- SKS，Sequence and Kitting System序列和配套系统，用于物料准备。

- SMART，Synchronous Material Replenishment Trigger同步物料消耗触发系统，用于计算物料的消耗和拉动。

- eCATS, Electronic Customer Acceptance Test System电子化客户接收检验系统，用于总装车辆的自动化检测，如四轮定位、刹车、灯光、尾气等。

这其中，NGAVS和EP、QLS VO、SMART、eCATS都有集成关系。

2. 架构特点

图3.3-1是NGAVS的架构示意图：

 

图3.3-1 福特NGAVS系统架构

架构要点：

1) 由线体PLC集成RFID阅读器和传感器，并通过PN/PN Coupler和IT PLC集成。IT PLC作为NGAVS的现场控制器。

2) IT PLC通过PLC网关实现信息格式转换，并通过MQ服务器和NGAVS应用服务器通信。PLC网关采用了西门子工业PC，并安装ILS DeviceWise软件，此软件能够自动将PLC信息转换成JAVA消息队列。

3) 应用服务器用于业务逻辑处理、外部系统接口通信、触发装车单打印等。

4) 客户端主要用于配置和查询处理。

3. 架构优点

1) 由于采用了IT PLC，现场调度的核心代码部署在IT PLC上，对线体PLC的逻辑影响较小，实施风险小。

2) 由于通过PN/PN Coupler进行IT PLC和线体PLC的通信，通信效率高并且实时，数据安全有保障。

3) 无论系统应用层还是PLC执行层都采用了标准模块、标准代码，工厂实施时订制化工作量小，实施难度得到控制。

4. 架构缺点

1) 由于大量采用IT PLC和PN/PN Coupler，硬件成本高。

2) 相对于主流OPC Server，ILS DeviceWise是一个较新的软件产品，存在一定的技术风险。

3) 由于RFID不缓存数据，线体PLC要获取车型信息必须和NGAVS实时集成，形成紧耦合设计，对系统可用性要求高。

康明斯NGMES介绍

康明斯是全球知名的柴油发动机制造商，NGMES是其全球统一实施的MES系统。

NGMES基于Apriso FlexNet平台开发，由制造工程部门的业务专家、控制专家，和IT部门的技术专家进行联合设计，由Apriso公司顾问指导，由Tata公司技术人员进行开发。

NGMES基于康明斯发动机制造流程设计，由于采用了通用化设计，可配置程序较高，因此也适用于零部件制造工厂。

1. 业务功能

NGMES不包含机加车间业务，覆盖了缸盖分装线、发动机内装线、外装线、检测线的整体业务。

其业务模块包含计划管理、工艺管理、零件追溯、料架防错、拧紧防错、设备防错、质量管理、质量门、装配防呆等。

计划模块能够自动接收ERP工单，并生成序列号下发给上线工位PLC。

工艺管理模块提供工艺BOM配置功能，提供界面将物料BOM进一步拆分到装配工位、配料工位、拧紧工位、料架位置、装配顺序、图片地址等，为防呆防错提供依据。

零件追溯模块提供序列号、批次号追溯形式，可实时配置。

料架防错通过与PLC集成，在发动机到达时，通过发动机序列号自动识别零件在料架上的位置，并通过料架灯通知工人，工人在捡料后料架灯自动熄灭，并自动判断防错是否完成。

拧紧防错通过与PLC集成，在发动机到达时，通过发动机序列号自动识别拧紧枪号、拧紧次数，并通过拧紧枪控制器通知工人，在拧紧作业完成后，自动采集拧紧数据。

设备防错通过与PLC集成，自动向设备下发工艺参数，并收集操作结果数据。

质量模块提供了质量报警、问题检查、缺陷管理、短装管理、质量评审、维修管理、报废管理等功能。

质量门工位会检查质量状态是否合格、是否漏工位、是否漏装多装、是否检测不合格、是否评审不通过、是否有缺陷未清除。

工人使用的NGMES客户端界面通过与PLC集成，当发动机到达时，自动显示发动机的产品信息和质量信息，以及要装配的零件顺序、要扫描的零件清单、关键零件图片、问题清单，从而实现装配防呆的效果。

此外，NGMES通过消息队列服务器从ERP接收工单，从PLM接收物料BOM。

图3.2-1是其业务架构示意图：

 

图3.2-1 康明斯NGMES业务架构

2. 架构特点

如图3.2-1所示，NGMES的系统架构非常典型：

 

图3.2-2 康明斯NGMES系统架构

NGMES基于Apriso FlexNet平台开发，其核心模块是Process Designer，用于定义核心业务逻辑和流程，同时也是一个集成开发和调试环境，能够直接调用数据库函数和存储过程，能够直接和OPC通信。

为提高运算效率，有大量业务逻辑直接写在数据库里，然后通过Process Designer调用，然后进行类型转换、流程跳转。

为简化构架，应用服务器集成了DB Client、OPC Client、MQ Client、打印机服务器等功能。

由于客户端采用B/S架构，因此采用网络服务器实现负载均衡。由于Apriso FlexNet基于.Net框架，因此支持本地JS脚本和DLL调用，如人工装配工位的OPC Client直接部署在客户端上，从而实现了OPC通信的分布式架构。

NGMES的重大特点是高度可配置和界面一致性，大部分装配工位运行的是同一个程序，程序界面根据工艺配置自动生成，根据PLC信号自动刷新页面和进行握手。

3. 架构优点

由于界面一致性高，操作工上手非常容易，可使用相同版本的培训文件，对所有工厂的同户进行集中培训。

由于基于.Net框架开发，组件工具多，界面友好，再搭配大尺寸触摸屏，工人操作方便，形象很高大上。

由于所有工厂采用相同的程序包，可在项目实施前搭建演示和培训系统。

由于高度可配置，所有工厂80%的业务功能使用相同的核心代码，只有20%的订制开发，因此实施周期短，通常一个大型项目只要半年的实施时间。

由于所有工厂使用相同的代码，可在全球共享设计、实施、运维团队。

4. 架构缺点

由于可配置性高，这就要求核心模块要考虑各种各样的应用场景，如装配工位界面有考虑：有没有追溯件(如有是什么规则)、有没有料架防错、有没有拧紧防错、有没有质量检查、有没有质量报警、有没有零件图片、有没有短装检查，这样核心程序的流程跳转逻辑就变得非常复杂，非常难以理解，当现场出现问题时难以迅速找到症结。

同样的原因，造成OPC侦听进程较多，拖慢了OPC响应速度。

系统逻辑部分部署在Process Designer，部分部署在数据库中，这样提高了应用服务器的响应速度，减少了应用服务器与数据库之间的I/O，但是运维人员对模块的设计更难以理解。

ANDON背后的管理思想

在很多现代化生产制造企业内，ANDON系统是一个非常重要的管理子系统，具体业务分析可参考本人的文章《MES在汽车制造中的应用之业务篇(13) -- 安灯呼叫》。

本文从企业管理的角度出发，论述ANDON背后所体现的企业管理思想。

评价工厂综合能力的一个重要指标是生产效率，即工厂在单位时间内产出的产品数量，如汽车主机厂最重要的指标JPH是每小时产出的车辆数量。

那么要提高生产效率，主要有两种方式。

方式一，提高生产能力。方法有：通过工艺改进，改进设备的利用率；通过培训提高工人的技能；通过生产线节拍平衡，提高工厂的整体效率。

方式二，减少生产浪费。方法有：通过控制质量，减少产出不良品；通过班组长和工艺工程师支持，减少工人因技能不足造成的时间浪费；通过设备工程师支持，减少设备异常造成的时间浪费；通过物流部门支持，减少物料不足造成的时间浪费。

ANDON又叫求援系统，主要是通过获取援助来减少生产现场的时间浪费。

我们可以把工人和设备看成一线生产作业单元，因为工人和设备的作业时间、作业效率决定了工厂的整体作业时间、作业效率；而质量、工艺、设备、物流等部门是二线生产作业单元，这些部门通过对工人和设备的援助来间接地提升工厂的整体效率。

我们可以用军事术语做一个类比。

如果把一个生产任务当成一个作战任务，那么计划部好比参谋部，提前做好作战计划；物流部好比后勤部，兵马未动，粮草先行；生产经理好比前线指挥，负责执行作战计划；工人和设备好比兵和马，奋战厮杀推进阵地；班组长好比基层军官，协调指挥基层作战单元；设备部好比装备部门，兵有甲，兵有鞍，射手有箭，如此才有士气；质量部门好比督战队，确保作战原则。

有了这个类比之后，我们可以把ANDON求援这样翻译。

向班组长求援：班长，有人受伤，请求援助！

向工艺工程师求援：我部有损，不敌敌军，请求中军援助！

向质量工程师求援：兵心混乱，请求督战队弹压！

向装备部门求援：盔甲有损，请速修复！

向物料部门求援：粮草不足，速速支援！