The nodes in a distributed control system require precise time synchronization to accomplish cooperation tasks. EtherCAT, as a commonly used serial bus in the industry, can only achieve time synchronization between sl...
详细信息
ISBN:
(纸本)9798350388640;9798350388633
The nodes in a distributed control system require precise time synchronization to accomplish cooperation tasks. EtherCAT, as a commonly used serial bus in the industry, can only achieve time synchronization between slaves. The time differences between the master and the slaves are relatively large. In this work, we develop a hardware assisted solution to achieve full time synchronization in the EtherCAT network. The proposed solution synchronizes all slaves with distributed clock to the master. The master time is maintained by programmable hardware and serves as the system time. Using the timestamps generated by hardware, the wire delays between the master and the slaves are calculated. During drift compensation step, the hardware embeds the master time into the drift compensation frame generated by the software. The proposed solution also compensates for changes in propagation delay caused by a cable disconnection, thereby quickly restoring synchronization performance. By performing extensive experiments, the proposed solution achieves synchronization accuracy of 0.1us in both single-port and cable redundancy mode. The means of system time differences are less than 30.54ns with standard deviations less than 36.23ns. The maximum change in system time differences when a cable is disconnected does not exceed 1us, and synchronization is restored within 50 drift compensations.
Grid-forming control demonstrates higher stability compared to grid-following control in expanding inverter-dominated power grids. However, parameters are not harmoniously adjusted for large-scale inverter-dominated g...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
Grid-forming control demonstrates higher stability compared to grid-following control in expanding inverter-dominated power grids. However, parameters are not harmoniously adjusted for large-scale inverter-dominated grids. For instance, while the damping factor can enhance the stability of local inverters, it may lead to instability in other inverters. Furthermore, existing literature fails to consider other performance metrics such as response speed and overshoot. Therefore, this letter proposes an online adaptive control based on reinforcement learning. Leveraging the flexible computing paradigm of cloud-edge-terminal systems, the proposed approach comprehensively assesses the performance of grid-forming inverters.
In single-bus DC microgrids, primary control poses challenges centered around achieving precise current sharing and restoring the DC bus voltage. While the implementation of droop control effectively addresses the for...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
In single-bus DC microgrids, primary control poses challenges centered around achieving precise current sharing and restoring the DC bus voltage. While the implementation of droop control effectively addresses the former, it frequently results in undesirable voltage deviations from its desired value. In response to this issue, this study introduces a distributed secondary control strategy based on the concept of 'virtual voltage drop (VVD)'. This strategy integrates VVD with a dynamic average consensus algorithm, thus ensuring accurate current sharing while compensating for voltage variations. Compared with existing results, the proposed strategy does not require the derivatives of VVDs to be bounded, which is more reasonable in practical applications. The efficacy of the proposed strategy is validated through three case studies.
Event-triggered control has achieved good results in reducing redundant transmission of network resources in wheeled mobile robots (WMR). Although event-based velocity control methods have made some progress in solvin...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
Event-triggered control has achieved good results in reducing redundant transmission of network resources in wheeled mobile robots (WMR). Although event-based velocity control methods have made some progress in solving the WMR trajectory tracking problem, these methods rely on the assumption that the kinetic moment controller can accurately provide the required velocity of the motion model and ignore the nonlinear characteristics such as wheel slip and universal wheel friction that exist in complex environments. This makes it difficult to achieve accurate tracking in practical applications. For this reason, an event-triggered sliding mode tracking control strategy is proposed to address the problems of uncertainty in the WMR center of mass position, perturbation of universal wheel friction, and wheel slip. Specifically, the corresponding event-triggered mechanisms are designed for the velocity and current loops, and combined with the designed virtual velocity control law and dynamic torque control law, to ensure that the error system is asymptotically stabilized while reducing the waste of resources. The neural network is also used to estimate the unknown friction force, which eliminates the influence of the perturbation brought by the universal wheel. Simulation results show that the control scheme has the ability to handle trajectory tracking and save transmission resources.
Despite the proven efficacy of learning-based control schemes, the absence of safety guarantees prevents their deployment in many applications. This paper addresses this problem by introducing a novel safety certifica...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
Despite the proven efficacy of learning-based control schemes, the absence of safety guarantees prevents their deployment in many applications. This paper addresses this problem by introducing a novel safety certification framework that leverages the principles of stochastic model predictive control. Our proposed framework modifies the actions taken by a learning-based controller in a minimally invasive fashion to enable non-conservative decision-making with adjustable safety levels for systems subject to additive unbounded noise. In addition to that, an ensemble of probabilistic neural networks is used to model the unknown aspects of the system dynamics. In situations where the proposed safety certification fails to find solutions, a constraint satisfaction probability maximizing backup algorithm is proposed. Finally, the efficacy of the proposed safety certification framework in reducing the number of violations is shown through simulations of reinforcement learning within a range of diverse environments.
The compensation of inverter nonlinearity is of great significance for improving the control performance of permanent magnet synchronous motor drive systems. In this article, an online inverter nonlinearity compensati...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
The compensation of inverter nonlinearity is of great significance for improving the control performance of permanent magnet synchronous motor drive systems. In this article, an online inverter nonlinearity compensation method based on the adaptive gain second order generalized integral is proposed for obtaining dq-axis current harmonics caused by inverter nonlinearity. Therefore, the complex offline test of the inverter nonlinearity can be avoided. In addition, considering the phase shift of the second order generalized integral filter and the time delay caused by controllers, a suppression strategy based on self-adjustment a bandwidth method is proposed. Finally, the method is verified on an 11.7kW permanent magnet motor test platform.
This paper designs an intelligent control module with STM32F103 microcontroller as the core, aiming at the 400A unipolar electromagnetic switch developed by our research team. This module has realized the joint optimi...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
This paper designs an intelligent control module with STM32F103 microcontroller as the core, aiming at the 400A unipolar electromagnetic switch developed by our research team. This module has realized the joint optimization of bounce suppression of the closing process, adaptive adjustment of closing time, collaborative optimization of the holding process reliability and energy-saving operation. Firstly, the step control strategy is adopted to effectively shorten the contact bounce time. Secondly, the dynamic iron displacement observer is constructed to successfully realize the adaptive switching of closing and holding processes. In addition, a collaborative optimization strategy based on the change of current slope is proposed for the characteristic difference of different reaction spring. This strategy optimizes the electromagnetic suction force by automatically adjusting the holding current, realizing reliable and energy-saving operation. Experimental verification confirms the effectiveness of bounce suppression and collaborative optimization strategies.
To solve the fast formation control problem of second-order multi-agent systems, an analytical design approach for the optimal distributed control protocol is proposed to track the time-varying reference velocity whil...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
To solve the fast formation control problem of second-order multi-agent systems, an analytical design approach for the optimal distributed control protocol is proposed to track the time-varying reference velocity while achieving the fastest formation. Firstly, the formation control problem of the original system is transformed to the consensus problem of the deviation system by model transformation, and necessary and sufficient conditions to achieve the formation are given. Secondly, explicit expressions of the optimal convergence rate and corresponding control gains to achieve the fastest formation are obtained by the Jury criterion. Finally, the validity of theoretical results is verified by simulation experiments.
This paper addresses the robust cooperative output regulation problem for uncertain linear multi-agent systems, where only regulated output signals are transmitted through the communication network. Firstly, a compens...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
This paper addresses the robust cooperative output regulation problem for uncertain linear multi-agent systems, where only regulated output signals are transmitted through the communication network. Firstly, a compensator is introduced to provide reference signals for the distributed design of control laws. Subsequently, a hybrid framework is employed to co-design the event-triggered mechanism and controller, consisting of a hybrid internal model and stabilizer. This approach ensures precise and accurate control actions both during trigger intervals and at trigger instants. In the third phase, the event-triggered mechanism is designed to be easily verified in smart sensors, utilizing only the output signal. This design choice effectively reduces communication burdens from the sensor to the controller, particularly in steady-state. Furthermore, the regulated error of each agent converges to a constant range, which can be adjusted to be arbitrarily small. To validate the proposed method, simulation results are presented.
Aiming at the problem of speed waveform overtwisting in the sensorless control system of permanent magnet synchronous motor, this paper combined the STA sliding mode controller and PI controller organically based on t...
详细信息
ISBN:
(纸本)9798350360875;9798350360868
Aiming at the problem of speed waveform overtwisting in the sensorless control system of permanent magnet synchronous motor, this paper combined the STA sliding mode controller and PI controller organically based on the Super-Twisting Algorithm (STA). A Fast Super-Twisting Sliding Mode controller (FST-SMC) was designed, and it was verified by simulation that its resistance to load disturbance was strong and the speed waveform almost had no overmodulation. Secondly, in view of the problems of large buffering and low observation accuracy of the traditional Sliding Mode Observer (SMO), this paper introduces the super-spiral sliding mode control rate into the observer and designs a super-spiral sliding mode observer. Simulation results show that the observer designed in this paper can accurately observe the rotor position and speed. Effectively reduce buffeting, with good anti-interference ability and robustness.
暂无评论