Application of FPGA technology in automotive electronics

Because field programmable gate array (FPGA) technology has the characteristics of custom logic functions and high reliability, engineers have integrated FPGA technology into the test system to solve the difficulties of automotive electronics design and test, while meeting low cost and system scalability Sexual and complex test environment requirements. This article will discuss the application of FPGA-related technologies in automotive electronics.

Application areas of FPGA technology

FPGA (Field Programmable Gate Array) is a product of the further development of programmable devices such as PAL, GAL, PLD, etc. Its logic function is completed by an array of logic cells arranged regularly inside. The logic cell array includes three parts: a configurable logic module, an input/output module and an internal connection (Interconnect). Engineers can use software programming to reconfigure the logic modules and I/O modules inside the FPGA to implement custom logic.

FPGA technology has many advantages, including custom I/O hardware timing and synchronization, high reliability, digital signal processing, and analysis. These advantages provide a flexible, low-cost solution to the rapidly growing automotive electronics test technology. Automotive electronics applications based on FPGA technology mainly include on-board data acquisition and hardware-in-the-loop (HIL) simulation of the electronic control unit (ECU).

1) Vehicle data collection

In-vehicle data acquisition system (IVDAS) is one of the most common automotive electronic test applications. It is mainly used to record and analyze the signals of various sensors in the car. At the same time, it has high reliability, portability and development of the test system. Requirements. The technical indicators involved in automotive applications include sampling rate, signal conditioning, processing, and analysis. For example, the sampling rate ranges from 15 Hz recorded by GPS data to 200 kHz for crash testing, because the FPGA can be directly connected to digital and analog I/O, and different sampling rates and triggers can be defined for each channel. Therefore, systems based on FPGA technology can solve these in-vehicle test applications at the same time, avoiding the need for custom hardware or multiple test systems. That is, a single FPGA platform can be used for low-speed, high-precision GPS or temperature recording; it can also be used for crash tests with high sampling rate requirements through rapid programming; or different sampling rates can coexist in the same measurement application in parallel, For example, when configuring FPGA to achieve 10Hz temperature acquisition and perform 50kHz vibration test; and can achieve synchronization between any I/O, for example, to achieve nanosecond synchronization measurement between CAN bus data and digital or analog I/O signals . Without FPGA technology, it is difficult to implement a single system to meet the needs of these different in-vehicle data collection.

Using FPGA technology, advanced signal processing and analysis of any sensor signal is also possible. In many signal processing systems, the underlying signal preprocessing algorithm has to process a large amount of data and requires high processing speed, but the algorithm is relatively simple and can be implemented by FPGA programming. In addition, various signal processing and analysis such as digital filtering operation, fast Fourier transform (FFT), windowing, etc. on the collected signals can be easily realized on FPGA. Sensor-level signal processing and analysis functions will make FPGA technology more suitable for vehicle data acquisition applications.

2) Hardware-in-the-loop simulation of ECU

As an important part of the design process, hardware-in-the-loop simulation is a very realistic simulation of the actual I/O of the devices in the virtual operating environment. The most obvious advantage is that it can simulate the actual situation without real danger. You can test the control device under extreme conditions that cannot be achieved in the real world-at the highest driving speed that the car can theoretically achieve. Powerful high-fidelity hardware-in-the-loop real-time simulation not only accelerates time to market by shortening development cycles, but also reduces equipment costs and related maintenance costs because no actual hardware is used during testing. ECU is an electronic device used for automobile engine and driveline control. It receives signals such as transmission speed, crankshaft and camshaft speed, and accelerator position. After processing this information, it generates signals and driveline parameters for controlling the engine. As one of the core components of the car, any slight error in the ECU design will cause the car to die. This makes hardware-in-the-loop simulation a standard method for testing ECUs before final use.

A typical hardware-in-the-loop system includes a controller for engine model simulation. The controller runs in a real-time environment and simulates various dynamic characteristics on the engine; the I/O module is used to receive the output signal of the ECU and pass through the engine The simulated signal is fed back to the ECU. Using FPGA technology, you can create custom I/O to meet the needs of various signals under the simulation conditions, such as knocking, sparks, engine position sensors, fuel injectors, and manifold pressure. Synchronous signal, and asynchronous signals such as switch, temperature, foot pedal, accelerator and vehicle speed; in addition, it also includes test data recording and test steps. In order to form a complete system, it also needs a host to run the operation interface, and cooperate with the corresponding test management software and subsequent data analysis software.

Because hardware-in-the-loop testing often requires systems to run at extremely high speeds, precise timing and synchronization between multiple input/output devices is extremely important. For example, you can output a variable reluctance sensor signal to the controller through the FPGA's I/O, and ensure that the controller turns the fuel injector on and off at the appropriate time and the correct current. Compared with traditional customized systems, FPGA-based systems have obvious advantages in achieving accurate and synchronized waveform generation and acquisition. It can synchronize multiple I/Os at high speed and quickly complete signal data and input / Conversion between output information.

In addition to implementing hardware-in-the-loop simulation of ECUs, FPGAs can also be used in rapid prototyping of ECUs to verify the effects of control algorithms and models from the hardware level. At the same time, the parallelism of FPGAs allows multiple fast control loops to be integrated in the same In the system. For example, Drivven’s application of FPGA’s reproducible configuration capabilities enabled the prototype design of the Yamaha YZF-R6 engine control system, while avoiding the need to purchase multiple custom hardware during the design process, thereby reducing costs.

Graphical FPGA programming

FPGA technology has many advantages, such as customizable logic, high reliability, etc., which can be widely used in vehicle test and ECU design process. However, engineers often need to master the knowledge of hardware design language such as VHDL when programming FPGA. Graphical development tools, such as National Instruments (NI)'s highly efficient graphical development environment LabVIEW, are designed for engineers and scientists who need to build flexible and scalable test and measurement and control application systems to meet their minimum Cost, the fastest speed to develop a system.

LabVIEW's intuitive graphical development features allow engineers to focus more on functional development rather than code writing, thereby greatly reducing development time and costs. LabVIEW is an open software platform. For some specific applications, it provides a variety of toolkits and modules to enhance and accelerate system development. For example, the LabVIEW FPGA module allows engineers to develop custom FPGA logic codes graphically on the Windows operating system and download to FPGA hardware targets without the need for hardware description languages and hardware design expertise. . As shown in Figure 2, LabVIEW FPGA is used to achieve nanosecond synchronization measurements between CAN data and digital or analog signals. When the test requirements change, you can download new code to the FPGA without the need for new custom hardware. At the same time, the VHDL language interface is provided to facilitate engineers to directly use the existing VHDL code. The LabVIEW Real-Time module is used to develop time-deterministic applications for real-time hardware targets. In addition, LabVIEW's additional simulation interface toolkit provides a seamless connection between LabVIEW and MathWorks Simulink(r) software (using this software you can import your algorithm model from Simulink(r) into LabVIEW). In short, the graphical development software LabVIEW will greatly improve the efficiency of engineers.

Using LabVIEW FPGA software and reconfigurable hardware technology, you can create high-performance control and acquisition systems. Here are two examples of the application of hardware platforms based on FPGA technology in automotive electronics.

User solution 1: Portable vehicle data acquisition system

Signal types for vehicle data acquisition include temperature signals (thermocouple, RTD), sound and vibration signals (acceleration sensors or microphones with IEPE excitation), pressure and load signals (strain gauges or load cells), position signals (LVDT or linear Potentiometer), speed signal (encoder), control bus signal (CAN, J1350, ODBII), and video signal. These signals are used to evaluate the performance of the car.

When faced with the above signal types, complex environmental conditions, and a large amount of data storage requirements, the German Goepel Electronic company chose the NI CompactRIO embedded control system, LabVIEW FPGA module, and LabVIEW Real-Time for portable test equipment for vehicle test analysis and online diagnosis. Time module. Developed CARLOS (in-car logging system) in a short time, coupled with the low-cost solution of CompactRIO platform, which greatly saves the budget.

The FPGA chip is the core of the CompactRIO architecture and is directly connected to the corresponding car module. The vehicle-mounted module can be directly connected with vehicle sensors, actuators and networks, and provides signal conditioning, isolation and vehicle bus. The platform contains an embedded real-time processor that can be used for independent work, deterministic control, vehicle data recording and analysis, etc. CompactRIO has a small, rugged mechanical package, can withstand 50g shock and -40 ℃ to 70 ℃ operating temperature range, etc., provides dual voltage input (9-35V), can be directly drawn from the car battery. All these make CARLOS suitable for complex in-vehicle test environment and limited test space.

The system has been successfully used in automotive testing in laboratories, wind tunnels, and proving grounds, and can record data for a long time. In addition, different test requirements can be achieved by selecting the corresponding vehicle-mounted module and the built-in application. For example, in order to realize the evaluation of the engine thermal management system in the winter or summer test, you only need to select the on-board module corresponding to the temperature and other signals and the developed LabVIEW application program; at the same time, the program provides alarms and is implemented with the LabVIEW report generation toolkit Data is written into EXCEL table, or directly into the database, historical data viewing and other functions. In addition, the FPGA-based CompcatRIO open test architecture allows users to expand the system or further develop custom test systems.

User Solution 2: HIL simulation for BMW V12 gasoline engine

MicroNova has developed a new and flexible programmable engine hardware-in-the-loop simulation system based on NI LabVIEW FPGA module and NI PXI-7831R reconfigurable I/O module, which can directly support the BMW 12-cylinder concept car. The simulation of the gasoline injector is the first system in the world that can simulate this situation.

The engine hardware-in-the-loop simulation system can record all gasoline injection time and ignition angle in synchronization with the crankshaft angle, and provide these data to the controller as a simulation input. At the same time, the input signal is collected through the analog, digital and pulse width modulator interfaces and the corresponding variable data is output. The simulation of the collision signal generates an output signal based on the rotation speed through up to six independent sensors according to the user-defined collision function.

NI's PXI platform provides the system with a complete selection of hardware modules, while PXI's advanced timing and triggering features ensure that the synchronous sampling between automotive signals reaches a microsecond-level trigger accuracy. The reconfigurable I/O module based on the PXI platform ensures high-precision and flexible acquisition engine high-speed sensor signals. Because FPGA is developed using LabVIEW, it is easy to change the corresponding combinational logic, and apply different software configurations for various engines with different numbers of cylinders, which greatly saves development costs and improves performance. At the same time, using the LabVIEW Simulation Interface Toolkit, the simulation model developed under MathWorks Simulink(r) can be quickly integrated into the LabVIEW platform, saving a lot of development time. In short, thanks to the modularity and flexibility of the PXI platform and FPGA-based reconfigurable I/O components, MicroNova has developed a high-performance ECU hardware-in-the-loop simulation system in a short time and successfully applied it Proof of the latest BMW 12-cylinder concept model.

To sum up

FPGA technology has brought innovations in automotive electronics test technology. With the development of a single system based on FPGA hardware, different automotive design and test applications can be solved without the need for multiple custom test equipment. Graphical FPGA programming based on LabVIEW further shortens development time. Both NI CompactRIO and PXI-based reconfigurable I/O modules are FPGA-based hardware platforms. Users can not only develop in-vehicle test applications that involve automotive buses and different signal types, but also be used for rapid prototyping in the automotive ECU design process. Verification and hardware-in-the-loop simulation testing.