Developing an Oil Pump Automated Test System Based on CompactRIO

"Considering our test requirements, using a traditional test system based on PCI data acquisition would be greatly impacted by the host computer or test environment OS. Development based on a PLC would also be limited by data acquisition speed and other conditions. Therefore, we chose to use NI CompactRIO technology."

- Huabin Dai, United Automotive Electronic Systems Co.,Ltd.

The Challenge:

Creating an oil pump bracket assembly test system that provides instrument control, motion control, and data acquisition.

The Solution:

Using NI CompactRIO hardware to develop a highly reliable, multifunction, real-time test system.

The XLM2 line-character test platform tests pump bracket assembly performance. For this case, we tested 12 GM and Ford pump bracket systems. The main parameters include oil-level resistance (tank safety gauge resistance); pump startup current; canister orient Earth resistance; drive reverse valve ground resistance; pump rotation polarity; and product barcode scanning. We correlate the test directly to pump bracket system specifications and quality. It is extremely important to set this character test platform as the final production line session.

 

Considering our test requirements, using a traditional test system based on PCI data acquisition would be greatly impacted by the host computer or test environment OS. Development based on a programmable logic controller (PLC) would also be limited by data acquisition speed and other conditions. Therefore, we chose to use NI CompactRIO technology.

 

CompactRIO, an open system based on field-programmable gate array (FPGA) technology, offers high reliability and precision. NI developed this system for complex industrial environments, and it is especially suitable for relatively poor working conditions that require high reliability and real-time performance. Compared with a traditional PLC, CompactRIO has a quicker response time and more data acquisition flexibility and control. Because its low-level hardware is open to users, instead of restricted by OSs and data acquisition modes, it offers great flexibility and reliability.

 

Functions and Hardware Architecture

 

 
There are three platform test functions. The first function, instrument control, includes TSG resistance, test servo motor control, scanner control, and polarity detector control. TSG resistance tests require the user to maintain the motor under test at a constant speed, and the whole process is divided into three stages (Figure 2).
 
 
The second function, analog signal acquisition, includes TSG resistance, Earth resistance, and DRV value measurements. The third function is I/O control.
 

Test System Architecture

Because this system is compatible with many types of tests, it would be difficult for a single data acquisition or I/O control device to meet all requirements. After comparing options, we selected an NI cRIO-9074 real-time controller because it offers low-level FPGA programming capabilities.

 

 

Control and Data Acquisition

Type

Output Type

Signal Type

Test

Range

Test

Accuracy

CompactRIO

Module Used

 Drive pulse for servo control

8-bit digital I/O

Pulse

0 Hz to 1,000 Hz

1 Hz

NI 9401

Feedback pulse for servo control

8-bit digital I/O

Pulse

0 Hz to 100,000 Hz

1 Hz

NI 9411

TSG test resistance voltage

16-bit

analog

I/O

Voltage signal

0 Hz to 5 V

0.01 V

NI 9205

DRV test resistance voltage

6-bit

analog

I/O

Voltage signal

0 Hz to 5 V

0.01 V

Canister orient test resistance voltage

16-bit

analog

I/O

Voltage signal

0 Hz to 5 V

0.01 V

Polarity sensor

1-bit digital I/O

Digital input

--

--

NI 9476

Barcodes scanner

RS232

RS232

±1

--

NI 9870

Cylinder electromagnetic valve

1-bit digital I/O

Digital output

--

---

NI 9425

Table 2. Analysis of Module Capabilities and Acquisition Volume

 

 

Automated Test Process

When the specimen is properly fixed onto the test fixture, the system automatically identifies it and determines whether or not it is correct. Once identified, the barcode scanner automatically scans the test specimen barcode. It then determines whether or not to perform a TSG resistance test, according to the type selected.

 

 


The system controls the motor screw to drive the specimen float and perform the TSG resistance test. Figure 9 shows the characteristic test process curve.

 

If the specimen passes the TSG resistance test, the system turns on the power and moves to the startup current test. Meanwhile, it compares the maximum startup current with the preset limit value. If the specimen passes the startup current test, the system opens the polarity sensor and starts the polarity test with the power on. After passing the polarity test, the system determines if it needs to perform a DRV resistance test. The CO resistance test process is similar to the DRV resistance test process. After qualifying the DRV resistance test, the system determines whether or not to perform the CO resistance test, according to the type selected.

 

Conclusion

The oil pump bracket test platform, which is based on CompactRIO, was specially developed for oil pump bracket testing. The system has been put into production, and its test results are stable. The system is achieving the desired results.

 

Author Information:

Huabin Dai
United Automotive Electronic Systems Co.,Ltd.
China
Huabin.dai@uaes.com

Table 1. System Architecture
Figure 3. Test System NI cRIO-9074 Controller
Figure 9. TSG Test Curve
Figure 4. Physical System Electrical Wiring
Figure 5. System Software Test Interface
Figure 1. Oil Pump Bracket Test Platform
Figure 2. TSG Resistance Test Process
Figure 6. Test Functions
Figure 8. Automated Test Process