Dissipative Filter Design for Nonlinear Time-Varying-Delay Singular Systems against Deception Attacks

This paper applies a T-S fuzzy model to depict a class of nonlinear time-varying-delay singular systems and investigates the dissipative filtering problem for these systems under deception attacks. The measurement output is assumed to encounter random deception attacks during signal transmission, and a Bernoulli distribution is used to describe this random phenomena. In this case, the filtering error system modeled by a stochastic singular T-S fuzzy system is established and stochastic admissibility for this kind of system is defined firstly. Then, by combining some integral inequalities and using the Lyapunov–Krasovskii functional approach, sufficient delay-dependent conditions are presented based on linear matrix inequality techniques, where the system of filtering error can be stochastically admissible and strictly ℚ , S , ℝ -dissipative against randomly occurring deception attacks. Moreover, parameters of the desired filter can be obtained via the solutions of the established conditions. The validity of our work is illustrated through a mostly used example of the nonlinear system.

Sliding Mode Control of Interval Type-2 T-S Fuzzy Systems with Redundant Channels

This paper investigates the sliding mode control (SMC) of interval type-2 (IT2) T-S fuzzy systems. The measurement outputs are propagated via redundant channels for reducing the probability of packet loss and improving the reliability of data transmission. A key feature for the above problem is that the premise variables and the measurement signals may not be available by the controller, which brings difficulty to stabilize the nonlinear systems. Accordingly, a crucial issue is how to synthesize an implementable SMC law under the redundant channels. To this end, the characteristic of the redundant channels is firstly analyzed and the model of available measurement output signals is established. By employing these available measurements as the premise variables and utilizing the upper and lower bounds of the system membership functions (MFs), new MFs are constructed and the sliding mode controller is synthesized. By introducing some null terms carrying the information of MFs, sufficient conditions are derived in terms of nonlinear matrix inequalities to ensure the stochastically ultimate boundedness of the closed-loop system and the reachability of the specified sliding surface. Besides, a binary genetic algorithm (GA) is introduced to solve the nonlinear criteria via the objective function reflecting the control performance. Finally, a numerical example illustrates the effectiveness of the proposed methods.

Modernising the Dynamometer for Grip Assessment: Comparison between GripAble and Jamar

Introduction: Maximal grip strength (MGS) is a reliable biomarker of overall health and physiological well-being. Therefore, an accurate and reliable measurement device is vital for ensuring the validity of the MGS assessment. This paper presents GripAble, a mobile handgrip device for the assessment of MGS. GripAble’s performance was evaluated using an inter-instrument reliability test against the widely used Jamar PLUS+ dynamometer. Methods: The MGS data from sixty-three participants (N = 63) measured using GripAble and Jamar PLUS+ were collected and compared. Intra-class correlation (ICC) was performed to evaluate the inter-device reliability between GripAble and Jamar PLUS+. The influence of gender and hand on MGS were also analysed. Results: GripAble demonstrates good-to-excellent inter-instrument reliability to the Jamar PLUS+ (ICC 3,1 =0.906). There were significant differences in the mean MGS between GripAble and Jamar PLUS+ (p <0.001 for both). GripAble’s measurement output is equivalent to 69% ([68-71]%) of Jamar PLUS+’s measurement output. The average difference in mean MGS between the two devices was 10.84 ± 4.18 kg ([4.77-18.54] kg), which increases with higher MGS. There were also significant differences in MGS between male and female and between right and left hands measured using GripAble and Jamar PLUS+ (p <0.001 for all comparisons). Conclusion: GripAble has good-to-excellent inter-device reliability with Jamar PLUS+, suggesting that it can be used clinically as a dynamometer whilst also providing additional functionalities, such as remote assessment, objective evaluation of compliance to standard protocol and assessing multiple facets of grip strength beyond the standard single maximum grip test. Normative MGS data using GripAble should be collected and integrated into the software for immediate comparison. Further studies, including test-retest and inter-rater reliability of using GripAble, are discussed. 1 www.gripable.co BMC Musculoskeletal Disorders-GripAble vs Jamar v1.0 15/07/2021

Placement of team sport GPS devices for reliability assessment

The goal of this study was to determine the effect of unit placement on signal integrity and measurement output obtained during reliability trials for global positioning system (GPS) devices. Two of the same model GPS units were worn in four separate unit configurations (Piggyback, Above-Below, Front-Back and Lateral) during 4 × 2 lap repeats of a team sport simulation circuit. Differences in signal integrity indicators (# satellites, horizontal dilution of precision (HDoP), signal-to-noise ratio (SNR) and signal strength (SS)), total distance covered in each lap, and distance covered above and below 3 m·s−1, were compared between the two units. The results showed that for signal integrity measures, differences between units were negligible for Above-Below and Lateral, but comparatively high for Piggyback and Front-Back. For distance measures, values were similar between units for Above-Below, however, discrepancies occurred in both total distance and speed distribution for the other configurations. This study concluded that the Above-Below unit configuration yielded the smallest differences between units for signal integrity and measurement output. Therefore, the Above-Below configuration is recommended for future GPS reliability investigations.

Observer-Based Distributed Fault Detection for Heterogeneous Multi-Agent Systems

This paper solves the distributed fault detection (FD) problem for heterogeneous multi-agent systems (MAS). For a heterogeneous MAS, we adopt a distributed control law to realise cooperative output regulation (COR) when no fault occurs in the MAS, and propose a state-feedback-based FD scheme, where the adopted distributed control law and proposed FD scheme all utilise state information. Furthermore, we consider the condition that state information is unmeasurable, the output-feedback-based distributed FD scheme is proposed, and the adopted distributed control law also utilises measurement output. Finally, two numerical examples are utilised to verify that the proposed distributed FD schemes could locate and remove the faulty agent in time.

A Quantum Kalman Filter-Based PID Controller

We give a concrete description of a controlled quantum stochastic dynamical model corresponding to a quantum system (a cavity mode) undergoing continual quadrature measurements, with a PID controller acting on the filtered estimate for the mode operator. The control has three feedback paths: P (proportional), I (integral) and D (derivative) of the error signal. Central use is made of the input and output pictures when constructing the model: these unitarily equivalent pictures are presented in the paper, and used to transfer concepts relating to the controlled internal dynamics to those relating to measurement output, and vice versa. The approach shows the general principle for investigating mathematically and physically consistent models in which standard control theoretic methods are to be extended to the quantum setting.

Monitoring of Heart Rate from Photoplethysmographic Signals Using a Samsung Galaxy Note8 in Underwater Environments

Photoplethysmography (PPG) is a commonly used in determining heart rate and oxygen saturation (SpO2). However, PPG measurements and its accuracy are heavily affected by the measurement procedure and environmental factors such as light, temperature, and medium. In this paper, we analyzed the effects of different mediums (water vs. air) and temperature on the PPG signal quality and heart rate estimation. To evaluate the accuracy, we compared our measurement output with a gold-standard PPG device (NeXus-10 MKII). The experimental results show that the average PPG signal amplitude values of the underwater environment decreased considerably (22% decrease) compared to PPG signals of dry environments, and the heart rate measurement deviated 7% (5 beats per minute on average. The experimental results also show that the signal to noise ratio (SNR) and signal amplitude decrease as temperature decreases. Paired t-test which compares amplitude and heart rate values between the underwater and dry environments was performed and the test results show statistically significant differences for both amplitude and heart rate values (p < 0.05). Moreover, experimental results indicate that decreasing the temperature from 45 °C to 5 °C or changing the medium from air to water decreases PPG signal quality, (e.g., PPG signal amplitude decreases from 0.560 to 0.112). The heart rate is estimated within 5.06 bpm deviation at 18 °C in underwater environment, while estimation accuracy decreases as temperature goes down.

Distributed Observer-Based Formation Tracking Control of Multi-Agent Systems with Multiple Targets of Unknown Periodic Inputs

This paper studies the distributed formation tracking control problem of heterogeneous multi-agent systems where the multiple targets have unknown inputs with finite dimensional Fourier decompositions and each target’s measurement output is just available to partial agents. A distributed observer-based formation tracking control algorithm is proposed. The distributed observers are based on the consensus protocol and designed to estimate the inputs and states of all targets from the available measurement outputs and neighbor information. The tracking controller is a state feedback based on the estimated state center of the targets. It is proved that the estimation errors of all agents converge to zero, if and only if each target node in the extended topology is reachable from each agent node and the consensus gain is larger than certain value. It is further proved that under the formation tracking control algorithm, the agents can asymptotically achieve predesigned formation and encircle the targets. A numerical simulation example is given to verify the validity of the algorithm.

Indoor Millimeter-Wave Propagation Prediction by Measurement and Ray Tracing Simulation at 38 GHz

The Millimeter-Wave (mmW) technology is going to mitigate the global higher bandwidth carriers. It will dominate the future network system by the attractive advantages of the higher frequency band. Higher frequency offers a wider bandwidth spectrum. Therefore, its utilizations are rapidly increasing in the wireless communication system. In this paper, an indoor mmW propagation prediction is presented at 38 GHz based on measurements and the proposed Three-Dimensional (3-D) Ray Tracing (RT) simulation. Moreover, an additional simulation performed using 3-D Shooting Bouncing Ray (SBR) method is presented. Simulation using existing SBR and the proposed RT methods have been performed separately on a specific layout where the measurement campaign is conducted. The RT methods simulations results have been verified by comparing with actual measurement data. There is a significant agreement between the simulation and measurement with respect to path loss and received signal strength indication. The analysis result shows that the proposed RT method output has better agreement with measurement output when compared to the SBR method. According to the result of the propagation prediction analysis, it can be stated that the proposed method’s ray tracing is capable of predicting the mmW propagation based on a raw sketch of the real environment.