"The tight integration between the Alma Automotive test environment, based on NI CompactRIO and NI LabVIEW, and the ESTECO optimization framework, helped us quickly create a demonstrator to automatically tune two ECU subsystems".
Enrico Corti, Alma Automotive
Providing custom solutions for engine development and testing is Alma Automotive’s core business. By applying optimization techniques to the automatic calibration of ECUs, the company, in close collaboration with ESTECO, addressed the challenge of reducing car manufacturing costs and development times. The high flexibility of National Instruments devices provided complete control over the engine and test bed, while the advanced algorithms of mF4LV allowed them to achieve targets quickly and efficiently.
The test environment for the automatic calibration system was set up as follows:
- the engine and test bench controllers (connected to the engine and to bench transducers/actuators respectively) include CompactRIO devices, programmed and equipped with FPGA boards;
- signals are sent from CompactRIO to two host PCs which store the data and set up the operating parameters. The interfaces developed by Alma Automotive provide easy interaction with the system;
- mF4LV runs on host PCs connected to the the engine controller.
The engine runs on a steady operating point identified by load and revolution speed: sensors send measures via CompactRIO to the destination PC. mF4LV is launched in combination with LABView and drives the engine controller (i.e. the ECU) to optimize the chosen target.
TEST 1 | Spark advance calibration for Maximum Brake Torque
Finding the optimal calibration for the spark advance on a real engine, mounted on a test bench, as quickly as possible.
The spark advance was controlled to achieve the Maximum Brake Torque value (MBT). The range of spark advance degrees was set on mF4LV which received the signals from in-cylinder pressure sensors. The signals were processed to obtain the target to be maximized (Indicated Mean Effective Pressure, IMEP). The mF4LV Simplex algorithm achieved maximum torque in 10 optimization iterations.
TEST 2 | Automatic fuel-film dynamics compensation
A fraction (X value) of the gasoline injected into an intake manifold of a spark ignition engine collects at the bottom of the intake runner wall and, once the evaporation time elapses, the deposited fuel goes into the cylinder. By identifying X and TAU values in real time, fuel-film dynamics can be compensated and delays in the engine reaction prevented.
The more the Lambda signal out-put resembles the expected injection profile, the higher the contribution of compensation. Therefore, with compensation “on”, the closer the signal waveform is to the ideal, the better the calibration. The automation capability of mF4LV allowed X and Tau values to be mapped and the optimal compensation strategy to be set up. The pictures above show the significant improvement brought on by the compensation.
- Reduce test steps, test time and calibration time
- Automate system calibration for system level testing
- Achieve a robust and accurate optimization process
The environment allowed test engineers to exploit the real-time processing characteristics of CompactRIO and the optimization algorithms included in mF4LV. Communication between systems is achieved by the combined use of LabVIEW and mF4LV, making the connection fast and simple.