VI-CarRealTime
Overview
VI-CarRealTime is an innovative product for engineers who want to quickly evaluate the handling performance of a certain vehicle configuration, who want to develop and adjust vehicle controller and want to test a prototype or production ECU in a real Hardware-in-the-Loop system.
The vehicle development team can experience how a design change affects the vehicle in a more subjective way, by allowing test drivers to get a feeling for the car, while driving the virtual vehicle on a motion base driving simulator such as VI-DriveSim.
All this with one single model and one single set of data! The different application modes are all based on a faster than realtime equation solver, which shares components with and has been validated against the industry standard ADAMS/Car from MSC.Software. This ensures high quality and enables an easy exchange of data between engineering teams in all phases of the development process, from conceptual to detailed design, and across the different disciplines, supporting the communication within the organization and with suppliers. The open architecture enables the use of proprietary definition of specific components, when required.
In the conceptual phase, it is difficult to create detailed virtual models, because the information to create such models is simply not available. VI-CarRealTime can be used to explore and improve the performance of vehicles at a conceptual level before building a detailed virtual prototype. In this target cascading process, VI-CarRealTime helps to determine the suspension characteristics required to satisfy the vehicle handling performance targets. Those requirements are then used for detailed suspension design within ADAMS/Car. During the verification phase the fast solution times of the VI-CarRealTime model derived from the detailed models enable the engineer to run a full stack of handling events including fish hook, lane change, braking in turn, etc. in a much shorter calculation time than ever before, thus allowing for more variations to be studied. The automatic process to generate the VI-CarRealTime model from the detailed ADAMS/Car model is a matter of seconds. An alternative method for obtaining data, describing the suspension characteristic, is to read in data from test.
Capabilities
VI-CarRealTime is a comprehensive and user friendly environment for modeling and simulating vehicles. It operates within its own GUI or embedded into a control environment such as MATLAB Simulink.
- Model data automatically derived from detailed models in ADAMS/Car, from VI-SuspensionGen or from test
- Shares modeling description for tyres, springs, dampers, and driver with ADAMS/Car
- Advanced driver and road model included
- Modular structure for Hybrid and Electric Drive simulation
- VI-Animator as Post Processor or use ADAMS/PostProcessor
- Export results in RES, CSV, TAB and other data acquisition formats
With the standalone mode no additional investment for MATLAB is required. The easy exchange of data is ensured by sharing the same property files describing springs, dampers, and tires between the different automotive applications (VI-CarRealTime and ADAMS/Car).
Benefits
VI-CarRealTime helps to reduce the time spent in the different engineering teams to obtain and prepare essentially the same data. It also improves the consistency of the engineering approach while providing state of the art technology.
- No need to validate the model from scratch when derived from detailed assemblies in ADAMS/Car
- Increase the number of design variations to be studied by several orders of magnitude
- Control engineers and vehicle dynamicists use the same driving tests, tires, and road models
- Easy exchange of data between engineering teams
- No switching between disparate, unconnected models while traversing through the design process
The investment pays off because it can be leveraged by many different teams including HIL engineers.
Static and Dynamic Tests
In VI-CarRealTime, you replicate your real world tests that are usually conducted in a costly hardware based environment. The virtual tests are conducted in the following categories:
- Tire test rig
- Full Vehicle test rig (4 and 7 post)
- VI-SpeedGen (Quasi Static) event
- Dynamic open and closed loop events
- Dynamic maximum performance events
You can select from a list of predefined events or create you own custom events. It is also possible to automate and organize your event test suites for different vehicles with fingerprints.
Quasi-Static Speed Prediction
The VI-SpeedGen event in VI-CarRealTime is used to define static limit velocity profile on a given driver line. The event uses a specific static solver (VI-SpeedGen) and a simplified model inheriting all properties from the full VI-CarRealTime one. The vehicle has no suspensions but considers the longitudinal and lateral load transfer as well aerodynamic forces.
VI-SpeedGen can also be used directly within VI-Road, such that the
visualization of the speed profile in the context with the driver line
the vehicle follows is more convenient.
Dynamic Events With VI-Driver
VI-CarRealTime takes advantage of the most advanced driver technology in the market. It is fast, robust, easy to tune and takes the vehicle to the limit without a cumbersome learning procedure , which other driver codes may require. With VI-Driver both open and closed loop maneuvers are allowed. You may freely create your event combining different mini maneuvers where you define the steering, throttle/brake and shift control behavior. The product comes with a large library of example events including the associated road files. For ease of use special
- GUIs are available to setup the most common maneuvers:
- Constant Radius Cornering
- Braking in a Turn
- Impulse, Sine, Step and Swept Steer
- Straight Line Acceleration and Braking
To find out more on the technical details of this model please visit the research area on the VI-grade web site.
Maximum Performance Events Using VI-DriverR
VI-DriverR combines VI-SpeedGen and VI-CarRealTime’s and automatically finds the maximum speed of a car on a given driverline. An online check of the speed profile feasibility is performed and local recursive corrections of the speed profile on individual track segments are determined. VI-DriverR pushes the vehicle dynamically to the limit while considering the:
- Path distance
- Yaw rate limits
- Longitudinal speed threshold
- Wheel Locking
You can now easily conduct press maneuvers such as a ISO lane change and more accurately predict lap time on a track compared to quasi static approaches without the need to manually modify the speed profile the driver should follow.
3d Road and Path
The road profiles are generated with VI-Road. There are a number of predefined tracks and speedways available in the database delivered with the product. To create your own road you can assemble a complete profile with different sections based on measured data or analytical descriptions. You can drive the vehicle on:
- Race tracks
- Ovals
- Banked Steering Pads
- Banked Chicanes
The optimal path for the vehicle to follow is generated automatically based on the 3D road profile with the Corner Cutting Tool. Smoothing of imported telemetry data is also possible.
Tyres
The tyre is one of the key components of the vehicle as it represents the interface between the road and the vehicle and it has a significant impact on performance. To capture the complex dynamic behavior of the tyres, a number of numerical models have been developed in the industry. VI grade has adapted and validated these models to include effects such as transient rolling radius, for example:
- Pacejka
- MF
All models run on 3D roads and allow investigation of curb crossings and variable friction surfaces.
Hybrid and Electric Drive
VI-CarRealTime is well suited to be combined with other codes such as MATLAB Simulink or Modelica. The process of adding control systems can be applied to any vehicle subsystem.
Validation
VI-CarRealTime is continuously improved in collaboration with our academic partners and customers. In this process, validation plays an important role. The plots to the right show a comparison between simulation and test. The channels displayed here are:
- Engine RPM
- Lateral acceleration
- Ride height
The plots below show the validation of a sportscar simulated with VI-CarRealTime against ADAMS/Car.
- Roll angle in Steering Sweep event
- Steering demand vs. lateral Acceleration
Control Design and Software in the Loop (SIL)
Often vehicle control engineers cannot reuse the same models vehicle dynamicists use to test their control systems because they are too complex. For controls design it is possible to include the VI-CarRealTime model as an S-Function or User Defined Block in a controls environment such as MATLAB Simulink. The VI-CarRealTime GUI broadcasts the model input in terms of vehicle date (e.g. spring rates, tire properties, roads,...) and in terms of event control for the virtual driver model via sockets.
Another option is to feed all the data thru files into MATLAB Simulink such that you can fully control the simulation from there. On top of that it is possible to group all events in so called fingerprints for a high level of automation. You may submit simulations with the VI-CarRealTime S-Function in Simulink directly or in batch mode. You can also animate the models motion during the simulation with the included post processing utility called VI-Animator. In that same utility you can plot the responses of the vehicle such as yaw rate or lateral acceleration and internal model states such as aerodynamic forces or brake pressure for example. VI-CarRealTime offers a way to derive all simplified vehicle data from detailed ADAMS models while providing a real time capable vehicle model, which uses the same driver, tire and road models as more detailed ADAMS models do. Control engineers can now use the same driving tests, tires and roads that are used by vehicle dynamicists to evaluate their control systems. VI-CarRealTime is designed to easily define your own models for almost all key vehicle components. Externally developed subsystem models can be easily incorporated into virtual models. A typical example for that is the incorporation of proprietary tire models.
Hardware in the Loop (HIL)
Vehicle OEMs and suppliers are being required to perform failure and field warranty analyses of the embedded control system prior to a vehicle being released. This requires the use of virtual models running in real time in conjunction with the controls hardware. After embedding your VI-CarRealTime model into the controls environment you can generate code for the most common platforms of HIL systems. With VI-CarRealTime, you can validate the embedded control system on a battery of tests even before the vehicle is available. The validation of vehicle designs is difficult and time consuming. With VI-CarRealTime you can sidestep questions about the accuracy of the model and intellectual property rights by using the actual hardware itself. This functionality can be provided on the following platforms:
- Concurrent
- ETAS
- dSPACE
- National Instruments (NI)
- Micronova
Because VI-CarRealTime is developed using software standards such as ANSI-C porting to new hardware and operating systems is easily possible.
Spa Francorchamps Example
The following movie shows the VI-CarRealTime model of an open wheeled racing car performing a maximum performance drive around Sps Francorchamps circuit
