Volvo Cars builds over 500,000 vehicles each year through factories in Sweden, Belgium, and China. Its R&D teams apply evolutionary and revolutionary problem solving in areas like electromobility, connectivity, and safety. The company believes that these transport innovations will reshape the cities of tomorrow.
The Driving Dynamics department defines and improves the driving experience for the latest generation of Volvo cars as well as vehicles still in the concept phase. This department can tweak a vehicle’s handling characteristics by adjusting the control, balance, and timing of the active chassis components. To deliver an intuitive driver experience, Volvo Cars also defines presets that, for example, allow customers to quickly switch between a dynamic mode on a country road to a more sporting drive on the highway. Air suspension, electronically controlled dampers, body control, and steering feedback are a few of the features that can be fine-tuned.
Volvo Cars has developed a variety of virtual test environments to validate vehicle dynamics attributes (like handling, steering, and ride) and verify vehicle motion control components (like braking, steering, and suspension). These virtual test beds incorporate elements of software-in-the-loop (SIL), hardware-in-the-loop (HIL), and, in the case of the Dynamic Driving Simulator, driver-in-the-loop (DIL) test.
The Dynamic Driving Simulator offers the efficiency and safety of simulation whilst delivering an emotionally resonant driving experience. It allows human drivers to physically feel the calculation models, so researchers can discern their subjective experience and confidence. The simulator offers exciting virtual environments including Germany’s renowned Nürburgring as well as test tracks at Volvo Cars’ own secret testing facility in Sweden.
The Dynamic Driving Simulator enables the Dynamic Driving department to:
• Test solutions in the concept development phase even before the prototype vehicle (chassis, suspension, and so on) is built or available
• Deliver repeatable testing of real driving situations and driver interaction testing, such as forward collision warning system testing, without the risk of crashing a vehicle
• Measure the immeasurable (great for requirement and method development, for example)
• Tune chassis characteristics, such as hard points, damper, and bushing, without using prototypes
Limitations of the Traditional Driving Simulator
The driving simulator is not used to validate, verify, and tune vehicle motion control systems because those processes have traditionally required physical prototypes. However, to reduce time and cost, Volvo Cars wanted to decrease the on-road testing requirements.
To achieve this, the driving simulator needed to be complemented with physical vehicle motion controllers, such as steering, brake, and suspension controllers. These improvements would:
• Add vehicle dynamics test capabilities while maintaining subjective testing capabilities
• Enable the calibration of vehicle motion control systems in a controlled computer aided engineering (CAE) environment
• Support vehicle motion control software development and verification in early phases
• Help researchers perform exploratory testing and thereby gain software test coverage
• Support continuous integration of software functional increments (stand-alone capability)
The extended driving simulator clearly offers significant benefits. However, it presents three daunting challenges. First, a vehicle motion control HIL test system needs to be developed and integrated into the existing virtual test environment. Second, the HIL tests need to be able to run stand-alone both with and without the Dynamic Driving Simulator. Lastly, validation needs to be completed in shorter timeframes even as the systems under test grow increasingly complex and test requirements change rapidly.
Strict System Requirements
Ideally, a validation system consists of the best, most practical solution from the right vendor with the right expertise. However, in reality, such a complex HIL system consists of different technologies from a variety of vendors, different RTOSs, different communication standards and vehicle buses, and different application software. Because of this, Volvo Cars needed an open and scalable platform to prevent being locked into one particular vendor.
Other requirements included:
• Modularity and flexibility to enable future expansion
• Seamless integration with the existing driving simulator
• Stand-alone operation
• Intuitive and cost-efficient design
• Support for open standards and the ability to integrate hardware and software from other vendors (for example, FMI, UDP/Ethernet, EtherCAT)
The Right Solution for a Complex Challenge
One year ago, Volvo Cars representatives met with NI engineers to learn about VeriStand and NI’s PXI HIL systems. These representatives determined that NI offered a solution that fulfilled all their requirements. After several meetings and impressive platform demonstrations, Volvo Cars selected the following configuration.
Real-time test execution and integration —A PXI Express eight-core controller running VeriStand on a real-time operating system (RTOS) worked well because VeriStand software features a wide range of out-of-the-box functionality, including configurable data acquisition and logging, test sequencing, and simulation model integration.
Vehicle dynamics simulation—IPG CarMaker software, which runs alongside VeriStand on the real-time controller, and off-the-shelf IPG CarMaker hardware helped Volvo Cars avoid building custom hardware, like wheel speed and torque sensors, from scratch. The openness of VeriStand, made adding third-party software and hardware components easy and efficient.
The existing Vector equipment needed to be integrated with the open HIL platform through an already available communication channel that allowed communicating between the VeriStand and Vector CANoe systems. EtherCAT communication, available out of the box, integrated with NI I/O, Beckhoff I/O, and Kollmorgen motion devices.
One Year Later
VeriStand has proved to be a powerful and reliable real-time test environment. By placing VeriStand at the heart of its HIL test architecture, Volvo Cars was able to:
• Use multiple vendors
• Use the right system for the right job and reuse existing components
• Build a flexible and modular HIL platform that is prepared for future needs
• Take advantage of the flexibility to integrate third-party hardware and software, such as IPG CarMaker software
Lastly, the ease of setting up the whole system enabled us to deliver world-class quality on time and at the right cost with limited resources.