Knee meniscus tear is a common joint disorder that is usually diagnosed with the help of MRI imaging. However, the diagnosis of a meniscal tear places high technical demands on physicians, and the results of the diagn...
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ISBN:
(纸本)9798350321050
Knee meniscus tear is a common joint disorder that is usually diagnosed with the help of MRI imaging. However, the diagnosis of a meniscal tear places high technical demands on physicians, and the results of the diagnosis are also inconsistent. In this paper, a meniscal tear detection method based on YOLOv5 target detection network is developed to help physicians make more accurate diagnoses. To begin, a channel and space parallel attention module is designed and integrated into the feature fusion part of the network to improve the network's attention to the tear area. Then, ConvNeXt is used in the backbone network part to improve the C3 module to obtain the ConvC3 module, which strengthens the ability of the backbone network to extract the features of the meniscal tear lesion area. After labelling and creating the dataset, the improved YOLOv5 network is trained to obtain the target model. The experimental results show that compared with the original model, the improved YOLOv5 model has an increased mAP from 82.5% to 84.8%, a slight decrease in GFLOPs as well, and presents an overall considerable improvement. This model plays an important role in the diagnosis of meniscal tears.
The 6th generation of mobile networks (6G) offers many advantages, including fast transmission rates, low delays, and ultra-dense networks. These benefits can solve the communication problems in the Internet of Vehicl...
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ISBN:
(纸本)9798350321050
The 6th generation of mobile networks (6G) offers many advantages, including fast transmission rates, low delays, and ultra-dense networks. These benefits can solve the communication problems in the Internet of Vehicles (IoV). However, automobiles as IoV terminals generate Non-Independent Identically Distributed (Non-IID) data while driving, making it necessary to introduce distributed machine learning into the IoV as a network that integrates intelligent computing and vehicle networking. To address the Non-IID of local data and the heterogeneity of local models, we propose a heterogeneous Federated learning scheme in this paper. Based on the distributed architecture (Terminal - Edge device - Cloud) in the IoV, we designed a privacy protection scheme using Secure Multi-Party Computation (SMPC). This ensures that the terminals participating in Federated learning get accurate calculation results without revealing useful information, thus preserving the privacy of local datasets. The privacy and security of the IoV based on Federated learning (FedVPS) not only protect the privacy of the terminals but also improve communication efficiency, enabling accurate and efficient distributed machine learning. The aggregation method of Federated learning is a prototype-based scheme that utilizes the effective information stored in local datasets. In the BIT-Vehicle dataset, FedVPS is not only more robust but also has excellent prediction accuracy. Compared to FedAvg, FedVPS has advantages in communication efficiency and model prediction accuracy.
Recently non-linear control methods like Model Predictive control (MPC) and Reinforcement learning (RL) have attracted increased interest in the quadrotor control community. In contrast to classic control methods like...
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ISBN:
(纸本)9798350377712;9798350377705
Recently non-linear control methods like Model Predictive control (MPC) and Reinforcement learning (RL) have attracted increased interest in the quadrotor control community. In contrast to classic control methods like cascaded PID controllers, MPC and RL heavily rely on an accurate model of the system dynamics. The process of quadrotor system identification is notoriously tedious and is often pursued with additional equipment like a thrust stand. Furthermore, low-level details like motor delays which are crucial for accurate end-to-end control are often neglected. In this work, we introduce a data-driven method to identify a quadrotor's inertia parameters, thrust curves, torque coefficients, and first-order motor delay purely based on proprioceptive data. The estimation of the motor delay is particularly challenging as usually, the RPMs can not be measured. We derive a Maximum A Posteriori (MAP)-based method to estimate the latent time constant. Our approach only requires about a minute of flying data that can be collected without any additional equipment and usually consists of three simple maneuvers. Experimental results demonstrate the ability of our method to accurately recover the parameters of multiple quadrotors. It also facilitates the deployment of RL-based, end-to-end quadrotor control of a large quadrotor under harsh, outdoor conditions.
Aiming at solving the model-free fault-tolerant spacecraft attitude control problem, a data-driven adaptive control scheme is proposed to the spacecraft in the presence of actuator faults and performance constraints. ...
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Aiming at solving the model-free fault-tolerant spacecraft attitude control problem, a data-driven adaptive control scheme is proposed to the spacecraft in the presence of actuator faults and performance constraints. First, the discrete-time attitude dynamic model is transformed into an affine nonlinear system based on local dynamic linearization. Then, a fuzzy logic-based lazily adapted constant kinky inference rule is introduced to predict the arbitrarily continuous nonlinear actuator faults and model uncertainties by supervised learning with insufficient prior knowledge. To satisfy time-varying deferred asymmetric constraints of the attitude tracking error, a virtual control law is proposed in the attitude control loop using the back-stepping approach, which is derived from a deferred switching transformation and barrier Lyapunov function. The stability of the data-driven adaptive fault-tolerant attitude control for the nonlinear discrete-time spacecraft attitude dynamics is analyzed rigorously with the aid of contraction mapping principle and discrete-time Lyapunov theory. Compared with existing methods, the proposed one considers nominal nonglobal Lipschitz nonlinear system with arbitrarily continuous unmodeled uncertainties and time-varying actuator faults, and achieves smaller prediction error bound than general kinky inference scheme and better closed-loop performance by estimating and compensating unknown dynamics. Finally, numerical simulation verifies the effectiveness of the proposed control scheme.
Leg-arm cooperative robot can not only expand the motion space of traditional manipulator, but also make up the operation ability of traditional mobile robot. This paper studies the target grab of leg-arm cooperative ...
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ISBN:
(纸本)9798350321050
Leg-arm cooperative robot can not only expand the motion space of traditional manipulator, but also make up the operation ability of traditional mobile robot. This paper studies the target grab of leg-arm cooperative robot based on vision. First of all, independently develop the leg-arm cooperative robot. Secondly, for the operation of the manipulator, a height-angle uncoupling PID algorithm is innovatively designed in the cylindrical coordinate system. The target position information obtained by the YOLOv3 algorithm is used as feedback to realize the accurate control of the manipulator, which can avoid the complex process of trajectory planning. Furthermore, combined with three-element trajectory planning method and motion control scheme under triangular gait, a target grab control strategy for the leg-arm cooperative robot is designed, including the height allocation decision maker and the target tracking controller. Finally, the proposed algorithm and schemes are verified with the entity robot.
controlling antenna tilts in cellular networks is critical to achieve a good trade-off between network coverage and capacity. We devise algorithms learning optimal tilt control policies from existing data (passive lea...
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controlling antenna tilts in cellular networks is critical to achieve a good trade-off between network coverage and capacity. We devise algorithms learning optimal tilt control policies from existing data (passive learning setting) or from data actively generated by the algorithms (active learning setting). We formalize the design of such algorithms as a Best Policy Identification problem in Contextual Linear Bandits (CLB). In CLB, an action represents an antenna tilt update;the context captures current network conditions;the reward corresponds to an improvement of performance, mixing coverage and capacity. The objective is to identify an approximately optimal policy (a function mapping the context to an action with maximal reward). For both active and passive learning, we derive information-theoretical lower bounds on the number of samples required by any algorithm returning an approximately optimal policy with a given level of certainty, and devise algorithms achieving these fundamental limits. We apply our algorithms to the Remote Electrical Tilt optimization problem in cellular networks, and show that they can produce optimal tilt update policy using much fewer data samples than naive or existing rule-based learning algorithms. This paper is an extension of work presented at ieee International conference on Computer Communications (INFOCOM) 2022 (Vannella et al. 2022).
This study proposes an iterative learningcontrol (ILC) scheme for a two-sensor system with user's preference. ILC updates the system input using error information from previous iterations to sequentially enhance ...
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False data injection attacks (FDIAs) targeting AC state estimation pose significant challenges, especially when only power measurements are available, and voltage measurements are absent. Current machine learning-base...
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False data injection attacks (FDIAs) targeting AC state estimation pose significant challenges, especially when only power measurements are available, and voltage measurements are absent. Current machine learning-based approaches struggle to effectively control state estimation errors and are confined to the data distribution of training sets. To address these limitations, we propose the physics-informed extrapolative adversarial variational autoencoder (PI-ExAVAE) for generating controllable and stealthy false data injections. By incorporating physically consistent priors derived from the AC power flow equations, which enforce both the physical laws of power systems and the stealth requirements to evade bad data detection mechanisms, the model learns to generate attack vectors that are physically plausible and stealthy while inducing significant and controllable deviations in state estimation. Experimental results on ieee-14 and ieee-118 systems show that the model achieves a 90% success rate in bypassing detection tests for most attack configurations and outperforms methods like SAGAN by generating smoother, more realistic deviations. Furthermore, the use of physical priors enables the model to extrapolate beyond the training data distribution, effectively targeting unseen operational scenarios. This highlights the importance of integrating physics knowledge into data-driven approaches to enhance adaptability and robustness against evolving detection mechanisms.
This article investigates the issue of finite-time annular domain stability (FTADS) of switched positive linear systems (SPLSs), particularly focusing on the incorporation of the concept of average dwell time (ADT). B...
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This paper is dedicated to studying the prescribed performance control (PPC) problem for nonlinear multiagent systems with saturation and unknown disturbance. A filter that integrates second-order sliding mode techniq...
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