The concern over safety features in autonomous vehicles is increasing due to the rapid development and increasing use of autonomous driving technology. The safety evaluations performed for an autonomous driving system cannot depend only on existing safety verification methods, due to the lack of scenario reproducibility and the dynamic characteristics of the vehicle. Vehicle-In-the-Loop Simulation (VILS) utilizes both real vehicles and virtual simulations for the driving environment to overcome these drawbacks and is a suitable candidate for ensuring reproducibility. However, there may be differences between the behavior of the vehicle in the VILS and vehicle tests due to the implementation level of the virtual environment. This study proposes a novel VILS system that displays consistency with the vehicle tests. The proposed VILS system comprises virtual road generation, synchronization, virtual traffic manager generation, and perception sensor modeling, and implements a virtual driving environment similar to the vehicle test environment. Additionally, the effectiveness of the proposed VILS system and its consistency with the vehicle test is demonstrated using various verification methods. The proposed VILS system can be applied to various speeds, road types, and surrounding environments.

In this study, a fault-tolerant control system is proposed for brake actuators in a vehicle. A degradation in deceleration performance and lateral stability caused by brake actuator failure can cause serious safety issues. The integration of braking system with either the drive or steering actuators has performance limitations, and previously studied fully integrated braking, driving, and steering systems have complex structures. Therefore, a coordinated control approach for fault-tolerant control of brake actuators was proposed herein to achieve a coordinated control of the drive, brake, and steering actuators. The drive and brake controller performed optimal torque allocation of the desired longitudinal force and yaw moment, and a constraint was set to ensure that the yaw moment error did not exceed the allowable limit. The unachieved yaw moment in the the drive and brake controllers was compensated by the front and rear wheel feedforward steering angles of the steering controller. This structure improved deceleration performance and lateral stability by allowing a certain amount of imbalance in braking force and compensating for it with the steering control. The fault-tolerant control system was verified via simulations and experiments, demonstrating that additional control of driving and steering improved the deceleration performance and lateral stability, respectively. Simulation results revealed that the proposed strategy considerably improved lateral stability compared to independent control strategy using the same actuators. The experiments further verified the applicability of the proposed strategy to vehicles and confirmed that yaw rate errors were reduced under both single and dual brake actuator failure conditions.

In this study, the chassis design target setting for a high-performance car was performed using a virtual prototype to solve the problem of increasing complexity of vehicle development. To achieve efficient handling performance of Hyundai Avante N, a high-performance vehicle, the kinematic and compliance (K&C) characteristics of the chassis corresponding to the design target were set prior to the design process using virtual simulation, thereby facilitating the efficient and systematic development of the actual vehicle. In order to overcome the limitations of existing research and apply it to the actual development of mass-production vehicles, the following major tasks were performed. The first is setting quantitative factors that match the sensibility evaluation. The second is building a virtual model to ensure consistency in performance predictions. The third is optimizing the chassis characteristics to achieve the vehicle performance goal. When all optimization results were applied, the average of the performance items increased by 0.5 points and the standard deviation improved by 0.4 points compared to the existing Civic Type-R, which was the best. In the case of the final specification considering design constraints, the average of performance items increased by 0.1 point and the standard deviation improved by 0.5 point compared to the existing Civic Type-R. Therefore, the design target of the chassis systems that could achieve the vehicle handling performance goal could be established prior to the design. Using this virtual development, it is possible to eliminate the trial and error process that the first and second test cars needed. This could save more than 500,000 USD (per unit trim) of the first and second test vehicles.

This study introduces a real-time optimization framework for eco-driving of heavy-duty vehicles over long-distance routes. A longitudinal dynamic model incorporating powertrain performance and fuel consumption is formulated, and the eco-driving scenario is expressed as a quadratic programming (QP) problem. To improve computational efficiency, a novel variable-step spatial segmentation method is introduced, which ensures a balance between modeling accuracy and computational cost. Simulations involving mixed-terrain scenarios verify the effectiveness of the proposed approach. The results show that the QP-based method achieves fuel savings comparable to those offered by dynamic programming while significantly reducing computation time to sub-second levels; thus, the proposed strategy offers real-time applicability. These findings demonstrate the feasibility of global optimal velocity profile generation in practical eco-driving scenarios.

This study proposes a fault-tolerant control strategy to solve the performance degradation problem due to kingpin offset, especially the negative kingpin offset condition, when steering torque failure occurs in a Steer-by-Wire (SbW) system. Previous studies overlooked kingpin offset, particularly negative offset, and lacked methods for practical control under such conditions. To this end, differential-braking experiments were conducted using an experimental vehicle with a negative kingpin offset to verify the vehicle model. Using the validated model, offline optimization was conducted to identify the control inputs that maximize yaw rate across varying offset and speed conditions, revealing limitations of the conventional approach. Based on this analysis, differential-braking distribution guidelines for each kingpin offset were derived, and a torque distribution controller that reflects kingpin offset was proposed by utilizing the steady-state yaw rate gain of the front and rear wheel differential braking. The proposed strategy was evaluated through open- and closed-loop tests in the full vehicle model and IPG CarMaker simulation environment. The evaluation results showed that the conventional strategy had problems such as performance degradation and unintended vehicle turning under some kingpin offset conditions; however, the proposed strategy showed improved and consistent turning performance within the tested kingpin offset range (-30 to +30 mm). The control error and control effort were reduced over the entire tested kingpin offset conditions compared with that of the conventional strategy.