Jianlong Zhang

Longitudinal control of heavy trucks in mixed traffic: environmental and fuel economy considerations

In this paper, longitudinal vehicle-following controllers for heavy trucks with different spacing policies are designed, analyzed, simulated, and experimentally tested, and their performance in mixed traffic with passenger vehicles is evaluated. A new vehicle-following controller for trucks, which has better properties than existing ones with respect to performance and impact on fuel economy and pollution during traffic disturbances, is developed. The response of trucks to disturbances caused by lead passenger vehicles is smooth due to the limited acceleration capabilities of trucks whether they are manual or equipped with adaptive cruise control (ACC) systems. Vehicles following the truck are therefore presented with a smoother speed trajectory to track. This filtering effect of trucks is shown to have beneficial effects on fuel economy and pollution. However, it creates large intervehicle gaps that invite cut-ins from neighboring lanes, creating additional disturbances. These cut-ins, under certain realistic scenarios, may reduce any benefits obtained by the smooth response of trucks as well as increase travel time. The results of this paper indicate possible benefits trucks may have in mixed traffic and also reinforces what is already known-that trucks could be detrimental to traffic flow

A simple roadway control system for freeway traffic

In this paper, a roadway control system that regulates variable speed limits along the freeway in addition to ramp metering is proposed to counteract traffic congestion and improve freeway efficiency. It treats the speed limit for one freeway section as a virtual ramp meter for the downstream freeway section. The control design is only based on the fundamental flow density relationship and can be easily implemented in real-time applications. Compared with the previous roadway control systems, the proposed control system requires less modeling information and computational effort. Simulation results are presented to demonstrate the efficiency and robustness of the proposed roadway control system

Design and evaluation of a roadway controller for freeway traffic

In this paper, a roadway controller that optimally coordinates speed limits and ramp metering to improve freeway traffic efficiency is designed using the model predictive control (MPC) methodology. The performance of the roadway controller is evaluated using a microscopic model, which is constructed and validated with field data from the Berkeley Highway Laboratory (BHL). Our simulation results demonstrate that the proposed controller reduces traffic congestion and the total time spent (TTS) in the network by up to 12%.

Automated container transport system between inland port and terminals

In this article we propose a new concept called automated container transportation system between inland port and terminals (ACTIPOT) which involves the use of automated trucks to transfer containers between an inland port and container terminals. The inland port is located a few miles away from the terminals and is used for storing and processing import/export containers before distribution to customers or transfer to the terminals. We design and analyze the ACTIPOT system with particular attention paid to the overall supervisory controller that synchronizes all the operations inside the ACTIPOT system. We employ the technique of truck platooning in order to simplify the control of the overall system and to minimize the possibility of deadlocks, congestion, and failures. A microscopic simulation model is developed and used to demonstrate the overall performance of the ACTIPOT system. The contribution of this article is the design, analysis, and evaluation of the new concept ACTIPOT.

Adaptive Vehicle Following Control System with Variable Time Headways

In this paper, we design a vehicle following control system with variable time headways, using adaptive control design methodology. It is shown that the designed vehicle following control system guarantees closed-loop system stability, and that it regulates the speed and separation errors towards zero when the lead vehicle is at a constant speed. Simulation results are presented to demonstrate the performance of the proposed vehicle following control system when applied to a validated nonlinear vehicle model.

Longitudinal control of heavy trucks: environmental and fuel economy considerations

We design, analyze, simulate and experimentally test longitudinal vehicle following controllers for heavy trucks with different spacing policies and evaluate their performance in mixed traffic with passenger vehicles. A new vehicle following controller for trucks is developed that has better properties than existing ones with respect to performance and impact on fuel economy and pollution during traffic disturbances. Validated emission models for passenger vehicles and trucks are used to investigate fuel economy and emission benefits in mixed traffic in the presence of traffic disturbance. The simulation models used are validated using experiments with actual vehicles.

Safe Adaptive Control for Performance Improvement

In the past fifty years, adaptive control theory has reached a high level of maturity. However, applications of adaptive control in safety sensitive systems are still very limited. Conventional identifier based adaptive control may lead to poor transients during the learning process due to the conflict between parameter estimation and control. Their nonlinear nature makes it difficult to check stability and robustness bounds as done in the linear time invariant (LTI) case. As a result in applications where safety is at stake practitioners are reluctant to close the loop using an identifier based adaptive controller. In this paper, we propose a novel adaptive controller, referred to as safe adaptive controller, which is composed of a supervisor and two candidate controllers. One candidate controller is a LTI model reference controller that can always guarantee system stability, while the other is a model reference adaptive controller that can tune its parameters to counteract the changes in the plant. The supervisor evaluates the performance of the two candidate controllers without using any plant model information and activates the candidate controller leading to better transient response. It is shown that the system stability is guaranteed as long as the non-adaptive candidate controller is stabilizing. Simulation results are presented to demonstrate the proposed safe adaptive controller is able to achieve better performance than the two candidate controllers