Standard Motor Products, a manufacturer of automotive sensors and components, contracted Aegis Solutions to develop an end-of-line test system to perform functional tests on two different types of engine sensors.  The client required the system to be automated, accurate, reliable, and capable of testing 2,000 parts per shift.  In addition, stringent repeatability and reproducibility requirements had to be satisfied and the user interface had to be configurable for both English and Spanish speaking users.

The client’s engine sensor detects the teeth of a rotating vane that break the sensor’s magnetic field to produce a repetitive timing signal while the engine is running.  This timing signal serves as the backbone for all synchronized engine functions such as spark plug firing, valve control, and engine control module operations.

Aegis Solutions engineering team designed and developed a software controlled electro-mechanical system to perform the specified tests and meet the client’s requirements.  The test system includes easy change out sensor holding fixtures for the two types of sensors, a servo motor driven flywheel with vane for actuating the engine sensor, full operator safety system, and high speed data acquisition for signal capture and analysis.  To achieve the needed testing performance and accuracy, the test system requires precise control of its servo motor and synchronization of the acquired data with the motor movement.  Aegis Solutions engineers decided to take advantage of the tight integration between National Instruments PXI data acquisition platform and LabVIEW programming environment.

 Since the system is required to test two types of sensors with different physical characteristics, multiple holding nests are utilized to secure a part during testing.  Adequately securing the part proved crucial to delivering reproducible measurements. The holding nests are mounted on a platform, which is automatically lifted into position to allow the flywheel’s vane teeth to pass through the sensor’s magnetic field when the vane is turning.

Control of the test system requires discrete inputs for reading proximity sensors and safety signals, discrete outputs for controlling the pneumatic lift solenoids, clamps and turning power on/off, a servo controller for the motor, and data acquisition for reading the sensor’s output signal.  Bundling control and data acquisition modules using a PXI chassis and backplane allowed our engineers to minimize the space requirements for this hardware and obtain tight synchronization between the modules using the PXI backplane.

The custom written LabVIEW software provides a graphical interface for the user allowing them to select the type of part to tests and barcode in serial and model number information.  Once the setup information is entered and the test system detects a part in place and that the user has placed there fingers in safety rings, the software commands the test system to position the engine sensor with the flywheel and tells the servo motor to start turning.  Once the servo reaches its target speed, the sensor’s output signal is captured as a waveform through the PXI analog input module and stored to disk. The test system analyzes the waveform to determine the angular position of the edge of each tooth with respect to a reference point on the vane. These angles are compared against pass/fail limits to determine if the part is good or bad. 

The signal’s amplitude value and angular position data are stored to a Microsoft Excel compatible file for each part tested. In the future, Standard Motor Products can use this data for statistical process control and can create comprehensive reports for their customers.

A Cost-Effective Solution that Exceeds Requirements

Innovative ideas and good engineering allowed Aegis Solutions to develop a cost-effective test system that exceeds the client’s requirements.  Using this system, Standard Motor Products exceeds its testing throughput requirements while ensuring the correct functionality of every part shipped to their customers.