Time-delay Environment Research Articles

Time-Delay Deep Q-Network Based Retarder Torque Tracking Control Framework for Heavy-Duty Vehicles

The stability of brake control is an important guarantee for the safety of heavy-duty vehicles (HDVs) at high speeds. However, the electro-hydraulic actuation braking systems often exhibit a significant delay in seconds, which makes braking performance forecasting and control difficult. To address the torque tracking control problem with time delay, a deep inference and control method is proposed. First, a theoretical delay time under different rotating speeds is identified with a data-driven model. Then, a fast end-to-end prediction model is established to estimate the torque performance of the next step with delay information. The deep Q-network (DQN) learning approach is proposed to learn the experimental data by exploring and seeking the optimal control strategy in the time delay environment. A comparative simulation of the proposed DQN-based controller with or without considering time delay, and the rule-based method with or without considering time delay is implemented, and an online processor-in-the-loop (PIL) test with the edge computing device NVIDIA Jetson Xavier NX is performed on the robustness condition. The simulation results and PIL test results demonstrate that the proposed control framework achieves a great improvement in the torque tracking effect with time efficiency.

Polynomial-based Stability Analysis of Modified IMC-PID Controller for Piezoelectric Actuator System in Time Delay Environment

Piezoelectric actuators are widely used in several industrial applications requiring precision positioning. However, the positioning accuracy of this nonlinear actuator is severely limited by physical phenomenon such as hysteresis, uncertainties. Accordingly, to improve the performance of piezo micro–nano positioning system, appropriate control laws are designed to linearize the hysteresis through closed-loop approaches. A modified internal model controller (MIMC) is useful with regard to efficient computational hardware resource utilization when compared with the conventional approach provided the resulting controller is stable. This paper focuses on one such widely used and computationally inexpensive control framework in the form of PID-based MIMC to mitigate hysteretic nonlinearity in piezoelectric actuators with the aim to investigate the time delay uncertainty handling range of the controller. The system stability pertaining to time delay has been analyzed numerically and the maximum delay that the system can withstand without losing its stability, i.e. the delay margin has been determined using polynomial-based approach. It has been found that upon increasing the delay beyond a specific critical value, the controller performance is limited and the system turns unstable. Simulations carried out in time delay environment validate the theoretically achieved results.

Model-based control for second-order piezo actuator system with hysteresis in time-delay environment

Model-based control for second-order piezo actuator system with hysteresis in time-delay environment

The consistency control of mold level in casting process

A new multiple periodic disturbance rejection control for casting process is proposed in this paper. Firstly, a high-precision multiple periodic disturbance detection method is designed. The accurate frequencies of the disturbance can be obtained. By using the disturbance observer and a group of filters with additional delay items, multiple periodic disturbance can be suppressed under time-delay environment. Then systematic control design is achieved based on the robust stability analysis. Finally, the efficiency of the proposed method is shown by comparisons between different methods and time-varying disturbance rejection in the consistency control of mold level.

Study on Appling the Sampling Information Processor into the Shared Control System Identification in Internet

In order to realize the parameters estimation of shared plants by the server node in the Internet Based Shared Control System. We propose a new method that can online identify the model parameters through Internet Based Shared Control System under the time-varying and time-delay environment. By applying the Sampling Information Processor to the course of the shared plant online identification, we can decrease the influence of network factor in the online identification system .Taking out all ranks state variable of shared plant’s model by identification algorithm processor in server node, we realize the online identifying the model parameters of the remote terminal. Numerical computer simulations are performed to compare our system’ result with the existing system’ result without influence of network factor. Results show that our method is valid. Lastly, our method realizes to identify the model parameters of the controlled object in different region under the network environment, and extends the applications of the online identification system.

Perception of Delay in Haptic Telepresence Systems

Time delay is recognized as an important issue in haptic telepresence systems as it is inherent to long-distance data transmission. What factors influence haptic delay perception in a time-delayed environment are, however, largely unknown. In this article, we examine the impact of manual movement frequency and amplitude in a sinusoidal exploratory movement as well as the stiffness of the haptic environment on the detection threshold for delay in haptic feedback. The results suggest that the detection of delay in force feedback depends on the movement frequency and amplitude, while variation of the absolute feedback force level does not influence the detection threshold. A model based on the exploration movement is proposed and guidelines for system design with respect to the time delay in haptic feedback are provided.

Signal detection in a multiple time delay environment

Signal detection methods for an uncertain multipath environment are described. The multipath transmission channel is modeled considering a different transfer function from the source to each hydrophone of the receiving array. The signal-to-noise ratio (SNR) is assumed to be low. Based on a simple example, which is given together with Monte Carlo simulation results, the statistical behavior of the two ad hoc detectors previously proposed is compared with that of the log likelihood ratio detector, under incorrect modeling of multipath delays and low SNR conditions. It is shown that the proposed ad hoc detectors provide near-optimum performance under negligible delay inaccuracies, but are superior for increasing misadjustment in the delay assumptions. >