Application of HIL testing in the development of aero engine controllers

Currently, low-power piston engines still dominate the power system selection of light and low-speed aircraft. Traditional piston aircraft engines are mostly carburetor gasoline engines. This type of engine that uses carburetors to achieve oil and gas mixing has many natural defects: it is unable to adapt to temperature and degree changes to adaptively adjust the mixture, the start operation is complicated and the start reliability is ineffective, and the mixture regulation operation is complicated during flight.

With the development of engines and their control technology, new electronically controlled piston aircraft engines have begun to emerge in the market. The greater advantage of electronically controlled aviation engines is that they can quickly control the fuel injection volume according to changes in working conditions and environmental changes, so as to achieve better oil and gas mixing under various working conditions and environmental conditions. In order to have better engine comprehensive performance, it can also simplify driving operations during flight, alleviate pilot fatigue, and improve flight safety.

Compared with traditional carburetor engines, the core of the electronic control engine lies in the electronic control system. The safety and trustworthiness of the electronic control system directly determine the safety and trustworthiness of the entire power system. The controller occupies a core position in the entire electronic control system, which is a combination of software and hardware integration. For controllers such as aircraft engine controllers that require more safety and trustworthiness, development is very difficult. How to shorten the development cycle and save development costs for development quality is the primary issue faced by controller developers. In the entire controller development process, the importance of the testing process is self-evident. Through repeated iterative testing, as many problems and potential defects as possible in a short period of time, and continuous design optimization and verification of problems and defects are important means to improve the maturity of controller products.

The current mature system-level testing method in the field of aero engine controller development is semi-physical simulation testing. This test method combines the controller to be tested with the actual sensor, actuator and the controlled object simulated by combining software and hardware(Aero engines)A closed-loop system is formed for testing. By carefully designing test cases and combining automatic running scripts, the testing efficiency can be greatly improved and potential problems and defects of the control system can be discovered. In Haery Electronic Control Laboratory, there is also a semi-physical simulation testing system like this, which we callHIL(Hardware in loop)Test the system.

Compared with traditional bench testing systems,HILThe test system has the following advantages:

1. First, support parallel development. Before the actual engine engineering prototype is assembled, the controller function testing and verification can be completed without the actual engine prototype through HIL testing; thus, for controller testing and development, parallelism with engine development can be achieved in the entire sense.

2. Secondly, it can save a lot of development costs and shorten the development cycle. Since HIL testing is a test built in a simulation environment, a large number of bench tests and flight tests can be converted into simulation tests on the HIL system, greatly saving various costs and costs in the actual test process. At the same time, the test cycle has been greatly shortened.

3. Later HIL tests can simulate extreme working conditions that are difficult to simulate under actual testing conditions to achieve extreme working conditions. Some extreme working conditions are difficult to simulate in actual test benches or flight tests, while in HIL simulation environment, it is easy to realize the working condition simulation and complete the system performance test under the corresponding working conditions.

The HIL testing system of Haery Electronic Control Laboratory mainly consists of three parts: the test host, the HIL test cabinet, the actual sensor and the actuator. The test host runs the engine model. Through parameter configuration, the actual engine can be simulated. At the same time, the host realizes communication with the controller under test, and displays various operating parameters of the controller through the real-time interface; the HIL test cabinet connects external sensors, actuators and controller under test through various hardware boards. After the test controller is connected to the system, the test host cooperates with the HIL test cabinet and externally connected sensors and actuators to simulate the actual running engine, and forms a closed-loop system with the test controller. When running test cases, simulate various engine operating conditions, observe the controller's control behavior, and compare the expected behavior, thereby realizing simulation tests of various functions of the controller.

based onHILTest system to carry out controllerHILThe test includes the following links:

Step 1: Create a test project

Step 2: Configure the engine model and wiring harness production

Step 3: Build a test bench

Step 4: Write test cases based on functional requirements

Step 5: Carrying real load to perform tests

Taking the development of a controller equipped on the Haery DB416 engine as an example, the control algorithm of the supercharger control solenoid valve and the actual operation of the solenoid valve are tested.

Step 1: Create a test project

Create a motor configurationHILEngine model, defining input and output signal types based on engine controller sensor and actuator type.

Step 2: Configure the engine model and wiring harness production

The engine model is configured based on the engine's cylinder number, timing, intake and exhaust system parameters and other information, and a special test wiring harness is prepared based on the controller's input and output signal type and quantity.

Step 3: Build a test platform

Build a test platform according to the functions and loads required to be tested, such as equipped with fuel injectors, fuel metering valves, supercharger control solenoid valves and air flowmeters.

Step 4: Write test cases based on functional requirements

According to functional requirements, when writing test cases, you need to design a test operating condition. The test operating condition needs to cover all possible function activation and function prohibition conditions. At the same time, you determine the set of variables that need to be monitored and the clear expected results under the corresponding test operating conditions. The specific test process is shown in the figure below:

Step 5: Carrying real load test

1) Control the solenoid valve with the superchargerHILAfter the test platform is connected, the designed test operating conditions should include all possible solenoid valve activation and inactivation operating conditions. The design working conditions and expected results are as follows:

2) Operate according to the design working conditionsHILTest platform, compare whether the test results are consistent with the expected results. If it is consistent, the test passes; if it is inconsistent, the cause needs to be checked and corrected.

3) Write a test report.

Attached:HILTest system physical display diagram