Simulating Real Driving Maneuvers in Traffic using SUMO and GT-SUITE

The Need for Realistic Vehicle Operating Conditions  

In an era where mobility is becoming increasingly electrified, new engineering strategies are needed to properly optimize an entire vehicle system for both fuel and energy saving potential that account for a multitude of driving scenarios. 

Especially during local commutes with traffic, being able to predict both vehicle operational behavior, together with sensitivity to variable human factors such as a drivers’ behavior, enables engineering teams to develop better vehicles.  

Available traffic simulation tools like SUMO (Simulation of Urban MObility), VISSIM (Verkehr In Städten – SIMulationsmodell), AIMSUN (Advanced Interactive Microscopic Simulator for Urban and Non-Urban Networks), and others employ the traffic flow theory which describes drivers’ behavior and its impact on overall traffic performance. This approach typically investigates the behavior of the ego vehicle, a vehicle which contains sensors that perceive the external environment, together with various traffic actors, while ignoring the predictive details of the vehicle dynamics.  

By combining SUMO with GT-SUITE (a systems simulation platform), an engineer can study the behavior of a high-fidelity powertrain model within a real-world environment, considering the non-deterministic nature of traffic and driver behavior. This approach leverages vehicle simulation to the next level, offering more realistic vehicle operation and assessment of fuel/energy saving potential. 

Coupling Multiple Simulation Solutions to Model Traffic Behavior 

In this study, we coupled various simulation solutions to best model a realistic traffic scenario. We selected the open-source software, SUMO, which is a well-known tool in the field of traffic simulation. The coupling was implemented by leveraging SUMO’s TraCI (Traffic Control Interface) protocol, which allows users to establish interactions between other simulation tools. 

Easy coupling of both GT-SUITE and SUMO with Simulink enables us to use Simulink as a lead tool controlling the co-simulation process and data exchange between the ego vehicle in SUMO, and its dynamic response modeled in GT-SUITE. 

Once these solutions are combined, driver traffic decisions are completely managed by the SUMO driver using implemented car following, lane changing models, overtaking models, and traffic constraints. A vehicle model in GT-SUITE replicates the speed trajectory calculating energy consumption at the same time. The GT-SUITE vehicle model then estimates the potential limits of acceleration and/or speed for future vehicle movements/maneuvers. These vehicle dynamic limitations shared with the SUMO driver will keep the ego vehicle operating in accordance with those limits (See Figure 1 below).  

Figure 1: The Co-simulation Environment

Communication between traffic and vehicle dynamic simulation through Simulink enables the integration of additional subsystems or controls to the existing one. Therefore, a vehicle model and simulation of its dynamic can be easily used for numerous studies and development processes as a part of more complex simulation platforms. 

Simulating an Electric Vehicle (EV) in “New York City Traffic” 

Let’s look at an example. We’ll use one of the available SUMO traffic examples to look at an electric vehicle (EV) model in GT-SUITE. 

The main focus of this example model is to establish communication between these simulation platforms by being able to facilitate bidirectional communication while keeping the vehicle running within realistic powertrain operation. This was achieved by using available features of the powertrain physical and controls components to estimate limitations coming from different vehicle subsystems. An additional preprocessing of different powertrains coming from electric motors and battery management systems (BMS) regarding available traction force was also developed.   

At each communication update interval, the GT-SUITE plant model provides the current acceleration/deceleration limits to the SUMO driver model. Knowing this information, SUMO drivers will achieve additional level of fidelity and adjust their driving style according to the vehicle powertrain limitations (see Figure 2).  

Figure 2: Co-Simulation of SUMO and GT-SUITE for an Electric Vehicle (EV)

Knowing the vehicle model limits from the SUMO driver behavior allows us to engineer ego vehicle acceleration and speed that’s both realistic and achievable. On the image below (Figure 3), we can see the effects. In the Co-Sim mode (SUMO and GT-SUITE), the driver is less aggressive and keeps the vehicle running, considering available powertrain limits.  

From the plot below, we see that driver behavior is the same based on the initial aggressiveness when the powertrain limitations are not imposed. With this approach, the SUMO driver makes decisions freely until the physical model powertrain limitations are not reached. 

Figure 3: Comparison of Vehicle Behaviors: Co-Simulation vs. Standalone

In the example demonstrated, the limitations are imposed from the BMS which takes care of minimal and maximal battery voltage and maximal charge and discharge rates. 

Other vehicle component physical limitations: 

• Energy source systems including battery, super-capacitor, fuel cell or other current, voltage or temperature related torque limitations
• E-motor mechanical, electrical or temperature torque limitations 

Learn More About our Co-Simulation and Driving Simulation Capabilities 

In general, in addition to a vehicle’s physical component limitations, a user can impose acceleration or speed limits as a command from the advanced driving assistance systems (ADAS) controllers. 

Here, we recognize a broad usage of integrated simulation solutions for more sophisticated energy consumption and emissions; development of hybrid energy system controls logic, ADAS, applications in the field of vehicle to vehicle (V2V), or vehicle to infrastructure (V2I) communication. 

To learn more about our co-simulation capabilities visit this webpage here. Learn more about our hybrid and electric vehicle capabilities here. Contact us here to speak to an expert!