CIMS Test Setup
CIMS (Ceramax Integrated Measuring System) sensors are used for position measurement on hydraulic cylinders. The CIMS is build up out of a sensor containing two hall elements positioned 90 degrees in relation to each other and sensor electronics that can deliver quadrature, SSI, analog voltage and current signals proportional to the cylinder position. The software first tests and calibrates the hall sensor standalone and later tests the complete assembly keeping track of which sensor is placed in which assembly in a database.
In the testsetup, the hydraulic cylinder is simulated using a round wheel with CIMS grooves mounted on a motor. The motor is controlled by a motordrive which is controlled from LabVIEW through the profibus.
In the setup we can test up to 8 CIMS sensors, 8 complete CIMS assemblies or 4 Wheel sensors (another kind of cylinder position sensor) simultaneously.
Basic procedure of delivering a fully tested and calibrated CIMS is as follows:
- Test (up to 8) sensors (dual HALL elements) by measuring their signals (much like sin and cos waveforms) and internal temperature at various predefined temperatures and various distances to the cylinder.
- Determine offset and amplitude for the sin and cos signals under the various conditions and store them in a database
- After test, sensors are assembled with the electronics in a stainless steel housing. This complete unit is called the CIMS
- The CIMS is first calibrated on the setup. The software retrieves the correct sensor measurements from the database and programmes the calibration table in the CIMS electronics
- Test all output modes for the mounted CIMS units (quadrature, SSI, Voltage and Current)
Apart from the procedure above, which is basically the end-of-line production test and calibration procedure, the setup can also be used for R&D purposes. To facillitate this, users can control most I/O hardware manually. Also for R&D and for debugging purposes, every single hardware device used in the setup can be simulated by software.
To be able to perform quadrature decoding and SSI reading on 8 positions in parallel, a National Instruments FPGA card is used. It performs all analog and digital I/O with respect to the DUT's as depicted below.