Automotive HIL Testbed Reference Architecture


NI HIL Simulators provide an open, flexible solution that you can customize to adapt to changing research requirements. By combining modular hardware with VeriStand and by integrating with third-party modeling software, these systems help you take advantage of off-the-shelf components to reduce your setup burden and offer a common starting place for your research team members around the world. With the Automotive HIL Testbed Reference Architecture, researchers can prototype a wide variety of vehicular devices under test (DUTs).

1. Testbed Components
2. High-Level Testbed Architecture
3. Example Setup
4. Summary
5. Next Steps


1. Testbed Components

The automotive HIL Simulator is an open, modular testbed that integrates into your existing workflow while offering you the flexibility to adapt to future requirements. The simulator combines PXI and switch, load, and signal conditioning (SLSC) hardware with additional hardware in a single mounting rack. Each component provides unique functionality to the overall system.



Figure 1 (Left). The Automotive HIL Testbed Reference Architecture incorporates an HIL Simulator for prototyping DUTs.

Figure 2 (Right). HIL Simulator Rack Components


PXI is a rugged PC-based platform for measurement and automation systems. It combines PCI electrical-bus features with the modular packaging of CompactPCI. You can add specialized synchronization buses and key software features.

A major benefit of the PXI platform for hardware-in-the-loop (HIL) test is the wide range of I/O options that you can integrate into the testbed. As the automotive industry evolves to incorporate new technologies such as automotive radar, cameras with onboard image processing, V2X, and real-time GNSS position tracking, HIL testbeds must also evolve. With vision acquisition, high-performance FPGAs, and RF modules that meet the needs of the latest automotive standards, such as 77–82 GHz radar, the PXI platform is uniquely positioned to scale alongside cutting-edge automotive research projects.


SLSC extends PXI measurement hardware with high-power relays for signal switching, power loads, and additional inline signal conditioning capability. The system consists of a chassis with built-in active cooling that can host 12 modules. SLSC plug-in modules can operate in the chassis in three different modes: stand-alone, pass through, or cascaded. You can use cascaded mode to implement functionality like signal fault insertion. You can choose from a variety of NI and third-party modules or create your own based on a detailed hardware and software development kit from NI. 

SLSC is designed to simplify overall system integration so you can reduce system point-to-point wiring by accumulating signals and using standard cables. Each SLSC chassis consists of an SLSC digital bus that you use to discover, configure, and set parameters on the individual modules. Signals pass through the SLSC modules from either the front connector or the rear expansion connector. You have the flexibility to design your own secondary backplanes to reduce system wiring using a custom application-specific backplane integrating the signal flow.


VeriStand is a software environment for configuring real-time test and HIL applications. Out of the box, VeriStand can help you construct a multicore-ready real-time engine to execute tasks such as real-time stimulus generation; data acquisition for high-speed, conditioned measurements; and custom channel scaling.

You also can use VeriStand to import control algorithms, simulation models, and other tasks from both LabVIEW software and third-party environments including The MathWorks, Inc. Simulink® software. You can monitor and interact with these tasks using a run-time editable user interface that includes tools for value forcing, alarm monitoring, I/O calibration, and stimulus profile editing. Although you don’t need programming knowledge to use VeriStand, you can customize and extend it with a variety of software environments such as LabVIEW, ANSI C/C++, and ASAM XIL.

VeriStand works with a real-time engine that runs independently from the user interface to ensure the deterministic timing of the HIL Simulator.


Additional Hardware
Because of the testbed’s modularity, you can add a wide variety of hardware, such as modules for data acquisition and embedded network protocols and integration with third-party systems.


2. High-Level Testbed Architecture

Figure 3. Block Diagram of Functionality and High-Level Signal Pathways


The testbed reference architecture defines methods of connecting signals. To reduce custom cabling and provide a common understanding of the way the signals are connected, the testbed uses standardized connector types and pinouts.

Figure 4 describes the signal paths from the mass interconnect through the measurement devices. It illustrates the power distribution for both AC and DC power and maps reference voltages from the DUT to the measurement and signal conditioning devices. Figure 4 illustrates the overall architecture from the signal perspective.


Figure 4. HIL Automotive Reference Design Signal Paths


The testbed uses two categories of lines: signal lines and power/reference lines. In Figure 4, the black lines represent instrumentation cables that adapt PXI/C Series devices to SLSC modules. These cables are intended to optimize the signal channels. The white arrows represent additional system cabling between the testbed components.


Signal lines are divided into three classes that are limited by the fault insertion technology used for each class, as shown in Table 1.


Table 1. Signal Line Class Specifications


Class I

Class II

Class III

Hold Current (Maximum) 2 A 8 A 30 A
Voltage (Maximum) 33 V 60 V/100 V 60 V/100 V
Connector Types HD 44, D-SUB 91 Positronic Scorpion2 16/4 Positronic2 8/2
Cables 4 Banks of 8 (32)
1 Bank of 8 (8)
4 Banks of 4 (16) 4 Banks of 2 (8)

1All cables male-to-male.

2All cables male-to-female.



3. Example Setup

Because of the modularity of the testbed, you can configure the hardware setup for automotive research with a variety of vehicular DUTs. You can customize the testbed further with generic sensor simulation using the testbed’s FPGAs. Figure 5 shows an example setup for automotive body chassis research. The diagram illustrates the pure signal paths from the PXI Express chassis, along with those that need conditioning from the SLSC components.  


Figure 5. Example Testbed Setup


4. Summary

The Automotive HIL Testbed Reference Architecture incorporates modular NI hardware and VeriStand to help you prototype a wide variety of vehicular DUTs. To learn more about using this architecture in your research, use the link below to contact your local NI representative.


5. Next Steps

Contact NI
View the Automotive Research Booklet
Learn More About Using the SLSC Architecture
View the HIL Simulators Product Flyer


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