Active Control of Tractor Semi-Trailer and Long Combination Vehicles

Active Control of Tractor Semi-Trailer and Long Combination Vehicles for Better Performance and Stability

Tractor semi-trailers and longer vehicle combinations, as shown in Fig. 1, have a higher possibility of becoming unstable when compared to vehicles without articulation [1]. When doing lane change maneuvers at high speeds, the trailers tend to oscillate. If the oscillations are large, it is possible for the vehicle to become unstable and cause an accident. The vehicle parameters have an effect on vehicle stability. An example parameter is the center of gravity of the trailer. Also, high speed gives higher tendency of instability.


Fig. 1. A-double combination, including tractor, semitrailer, dolly, and semitrailer.

There are several different long combination vehicle types. The most common one is the tractor semi-trailer. The other combinations include the addition of more trailers. During a lane change maneuver, the trailers do not oscillate the same amount. The yaw rate (turning rate) of a vehicle resembles one cycle of a sine wave during a lane change maneuver. However, every vehicle in the combination does not have the same maximum yaw rate during the lane change. There is a tendency for the maximum yaw rate to increase from the front of the combination to rear units. For example, for a tractor semi-trailer, the trailer has a higher maximum yaw rate than the tractor during a high-speed lane change maneuver.

The increase in the maximum yaw rate towards the rear of the combination is called rearward amplification. The rearward amplification would like to be minimized to achieve a more stable vehicle combination. Several control methods have been developed to minimize this rearward amplification. One method is using braking torque to stabilize the vehicle [2] and [3]. The related research project is [4].


The objectives of the master's thesis are as follows:

1. Investigate the effects of the vehicle parameters on the stability of tractor semi-trailers and longer vehicle combinations.
2. Determine some numerical sets of parameters that result in the most stable vehicles.
3. Develop control strategies that stabilize the vehicle.
4. Check the robustness of the controller to variations in vehicle parameters and road conditions.

Suitable background

The thesis work will require control theory, vehicle dynamics and signal processing skills. Interest in mathematical modeling seen as a benefit. MATLAB will be used as the primary development environment. The work will be carried out at Volvo Group Trucks Technology. The thesis is recommended for two students with vehicle dynamics and/or control analysis profile with good mathematical skills.

Thesis Level: Master

Language: English

Starting date: Jan 2024

Number of students: 2

Contact person:
basar.ozkan@volvo.com

Supervisors:
Basar Özkan – Volvo GTT
Christian Oscarsson - Volvo GTT
Nrupathunga Ashok – Volvo GTT
Leo Laine - Volvo GTT
Bengt Jacobson - Chalmers

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