A real-time system for tele-surgery

Feedback control techniques have recently been applied to a variety of real-time systems. However, a fundamental issue that was left out is guaranteeing system controllability and the feasibility of applying feedback control to such systems. No control algorithms can effectively control a system which itself is uncontrollable or infeasible. In this paper, we use the multiprocessor utilization control problem as a representative example to study the controllability and feasibility of distributed real-time systems. We prove that controllability and feasibility of a system depend crucially on end-to-end task allocations. We then present algorithms for deploying end-to-end tasks to ensure that the system is controllable and utilization control is feasible for the system. Furthermore, we develop runtime algorithms to maintain controllability and feasibility by reallocating tasks dynamically in response to workload variations, such as task terminations and migrations caused by processor failures. We implement our algorithms in a robust real-time middleware system and report empirical results on an experimental test-bed. We also evaluate the performance of our approach in large systems using numerical experiments. Our results demonstrate that the proposed task allocation algorithms improve the robustness of feedback control in distributed real-time systems.

Navigation in mobile robotics involves two tasks, keeping track of the robot's position and moving according to a control strategy. In addition, when no prior knowledge of the environment is available, the problem is even more difficult, as the robot has to build a map of its surroundings as it moves. These three problems ought to be solved in conjunction since they depend on each other. <br/>This thesis is about simultaneously controlling an autonomous vehicle, estimating its location and building the map of the environment. The main objective is to analyse the problem from a control theoretical perspective based on the EKF-SLAM implementation. <br/>The contribution of this thesis is the analysis of system's properties such as observability, controllability and stability, which allow us to propose an appropriate navigation scheme that produces well-behaved estimators, controllers, and consequently, the system as a whole. <br/>We present a steady state analysis of the SLAM problem, identifying the conditions that lead to partial observability. It is shown that the effects of partial observability appear even in the ideal linear Gaussian case. This indicates that linearisation alone is not the only cause of SLAM inconsistency, and that observability must be achieved as a prerequisite to tackling the effects of linearisation. Additionally, full observability is also shown to be necessary during diagonalisation of the covariance matrix, an approach often used to reduce the computational complexity of the SLAM algorithm, and which leads to full controllability as we show in this work.<br/>Focusing specifically on the case of a system with a single monocular camera, we present an observability analysis using the nullspace basis of the stripped observability matrix. The aim is to get a better understanding of the well known intuitive behaviour of this type of systems, such as the need for triangulation to features from different positions in order to get accurate relative pose estimates between vehicle and camera. Through characterisation the unobservable directions in monocular SLAM, we are able to identify the vehicle motions required to maximise the number of observable states in the system. <br/>When closing the control loop of the SLAM system, both the feedback controller and the estimator are shown to be asymptotically stable. Furthermore, we show that the tracking error does not influence the estimation performance of a fully observable system and viceversa, that control is not affected by the estimation. Because of this, a higher level motion strategy is required in order to enhance estimation, specially needed while performing SLAM with a single camera. Considering a real-time application, we propose a control strategy to optimise both the localisation of the vehicle and the feature map by computing the most appropriate control actions or movements. The actions are chosen in order to maximise an information theoretic metric. Simulations and real-time experiments are performed to demonstrate the feasibility of the proposed control strategy.

BER testers measure CDFs (cumulative density functions) in real-time; however, BER applications have been limited to using repeating PRBS (pseudorandom binary sequence) or fixed sequences. The paper presents altering the decision circuit to allow CDF accumulation in any data stream including "live" traffic.

The next few years will see distributed real-time computer systems playing an important role in control systems of high-dependability applications, such as rail transportation. In these applications a failure in the temporal domain can be as critical as a failure in the value domain. In rail transportation, train control system has become more complex and the methods to ensure its correctness of have been considered outmoded. The safety of train control system is becoming increasingly important as computers pervade them on which human life depends and the failure to meet time deadline can have serious or even fatal consequences. This paper proposes a formal modeling and verification approach for real-time system. In the proposed method the real-time system is modeled by timed automata network (TAN) and verified by model checking which explores the state space to determine whether the system satisfies a given specification. The case study of ATP (automatic train protection) shows how the method can assist in designing more efficient and reliable real-time systems. Firstly, automatic train protection (ATP) system and timed automata network (TAN) model is proposed; secondly, the state transitions and multi-tasks ATP onboard model was modeled with TAN model, and then the time sequences of each task are expressed in UML sequence diagrams. Finally, the timing characteristics was verified to meet the requirement by UPPAAL model checker. A major conclusion of the survey is that formal methods, while still immature in some respects, can be used successfully to model and verify real-time systems.

Dynamic compressors are known to suffer from surge, which can severely damage compressor components and disturb production. Surge may arise by the occurrence of disturbances (e.g. compressor discharge valve closure) that would bring its operating point to a region at low flows delimited by the so called surge line (SL). Therefore, dynamic compressors are always equipped with anti-surge mechanisms: typically a fast actuating recycle valve controlled by a PI anti-surge controller. Since surge develops extremely fast, the compressor is usually not allowed to operate too close to the surge line. A surge safety margin is considered, which is the region between the SL and a surge control line (SCL), which may be defined as a line parallel and to the right of the SL. Once the compressor crosses the SCL towards the SL, PI controller action starts. Depending on a number of factors the recommended surge margin adopted may vary. This control objective (keep the compressor away from the SL) is conflicting with energy efficiency requirements, since higher efficiency operating points are located close to the SL. Therefore, it is desirable to operate the compressor using the smallest possible surge margin that still guarantees anti-surge action is effective. In this paper we propose a method for triggering the compressor anti-surge action, aiming at a faster action than traditional PI control, which could enable the adoption of reduced surge margins and operation with higher efficiency. Given a typical single compressor system topology, the possibility of a compressor reaching the surge region coming from a stable operating point can be retrieved through the state of the system actuators. Considering a certain combination of values of the system actuators (compressor suction valve opening, discharge valve opening and motor drive torque), if the steady state operating point (calculated based on a nonlinear variable speed compressor system model) lies to the right of the SCL, then no anti-surge action is necessary. If the resulting steady state lies to the left of the SCL, anti-surge action is deemed necessary and therefore triggered. The proposed anti-surge control method relies on an offline computation of necessary recycle valve openings for each possible combination of the system actuators positions mentioned above, considering a predefined discrete set of values from the actuators positioning ranges. This generates a look-up table for online use. The values from the look-up table are used to trigger a “steady state control action” for the recycle valve that would keep the system stable after transients vanish. They are also used to identify the necessary compressor flow set-point for a feedback controller, which is responsible for ensuring that the system trajectory goes from the state upon anti-surge activation to the desired steady state. The control action from this feedback controller is added to the steady state control action so that its contribution should vanish after transients vanish. A PI and a sliding mode controller are used in feedback control action and results are compared to the traditional anti-surge control approach.

This work presents a detailed study, characterization, and measurement of video latency in a real‐time video streaming application. The target application consists of an automatic control system in the form of a control station and the mini Remotely Operated Vehicle (ROV) equipped with a camera, which is controllable over local area network (LAN) and the Internet. Control signal transmission and feedback measurements to the operator usually impose real‐time constraints on the network channel. Similarly, the video stream, which is required for the normal system control and maneuvering, imposes further strict requirements on the network in terms of bandwidth and latency. Based on these requirements, controlling the system in real time through a standard Internet connection is a challenging task. The measurement of important network parameters like availability, bandwidth, and latency has become mandatory for remotely controlling the system in real time. It is necessary to establish a methodology for the measurement of video and network latency to improve the real‐time controllability and safety of the system as such measurement is not possible using existing solutions due to the following reasons: insufficient accuracy, relying on the Internet resources such as generic Network Time Protocol (NTP) servers, inability to obtain one‐way delay measurement, and many solutions only having support for web cameras. Here, an efficient, reliable, and cost‐effective methodology for the measurement of latency of a video stream over a LAN and the Internet is proposed. A dedicated stratum‐1 NTP server is used and the necessary software needed for acquiring and measuring the latency of a video stream from a generic IP camera as well as integration into the existing ROV control software was developed. Here, by using the software and dedicated clock synchronization equipment (NTP server), it was found that normal video latencies in a LAN were in the range of 488ms – 850ms, while latencies over the Internet were measured to be in the range of 558ms – 1211ms. It is important to note that the values were obtained by using a generic (off‐the‐shelf) IP camera and they represent the actual latencies which might be experienced during control over long range and across international territory borders.

The performance of many digital systems today is limited by the interconnection bandwidth between chips. Although the processing performance of a single chip has increased dramatically since the inception of the integrated circuit technology, the communication bandwidth between chips has not enjoyed as much benefit. Most CMOS chips, when communicating off-chip, drive unterminated lines with full-swing CMOS drivers. Such full-swing CMOS interconnect ring-up the line, and hence has a bandwidth that is limited by the length of the line rather than the performance of the semiconductor technology. Thus, as VLSI technology scales, the pin bandwidth does not improve with the technology, but rather remains limited by board and cable geometry, making off-chip bandwidth an even more critical bottleneck. In order to increase the I/O Bandwidth, some efficient high speed signaling standard must be used which considers the line termination, signal integrity, power dissipation, noise immunity etc In this work, a transmitter has been developed for high speed offchip communication. It consists of low speed input buffer, serializer which converts parallel input data into serial data and a current mode driver which converts the voltage mode input signals into current over the transmission line. Output of 32 low speed input buffers is fed to two serializer, each serializer converting 16 bit parallel data into serial data stream. Output of two serializers is fed to LVDS current mode driver. The serial link technique used in this work is the time division multiplex (TDM) and point-to-point technique. It means that the low-speed parallel signals are transferred to the high-speed serial signal at the transmitter end and the high-speed serial signal is transferred to the low-speed parallel signals at the receiver end. Serial link is the design of choice in any application where the cost of the communication channel is high and duplicating the links in large numbers is uneconomical.

Production test and device I/O characterization are different tasks. Measurements and analysis associated with these different tasks need quite different tools. 1 Serial Data Links -the future is “bright” The 2001 ITRS predicted serial datacom rates reaching 40 GBPS by this year, doubling within a decade - and 40 GBPS production devices now exist. A 12.5 ps unit interval is tiny by today’s standards; for reliable data transmission to reach these rates the challenges are daunting. Despite this, we can fully expect such serial data links. What is required for them to be producible? Quite simply: reliable design, consistent process technology, and solid production test capability. 2 Design Qualification vs Production Test It is absolutely necessary to distinguish clearly between design qualification/characterization and the sort of test necessary to guarantee that a particular device is manufactured properly. Yet to sort one from the other is no mean task. It only takes a few extra ohms of interconnect to marginalize a good design; these few extra ohms will displace a transition by a few but unacceptably large number of picoseconds. Each bit in a high-speed serial data stream can be characterized by two key parameters: unit interval and individual edge displacement, expressed as a fraction of unit interval. Edge displacement is often referred to as jitter. Jitter is an unfortunate term, as it masks what is actually going on. Yes, some edges are out of place, but why are they? Displaced edges are created by intersymbol interference, internal systematic path or propagation delay errors, clock phase error, and random noise. These errors must be identified and minimized during the design qualification phase; the design is acceptable if error rate is sufficiently below target unless the product is defective. Key point: “random noise” in semiconductors is not very large. RJ in excess of 1 ps is more likely to be instrumentation noise than true circuit noise, or else is uncorrelated systematic error. This error is likely to be correctable in design. Laboratory equipment is generally capable of acquiring the data necessary to characterize today’s I/O designs. However, it is a costly mistake to attempt to translate these characterization tasks into a production test requirement. Measuring “jitter” in a production test environment is unneeded. What might be measured (and compared to design minimum, nominal, and maximum) are bit-by-bit displacements focused specifically on the structure of the specific serializers or deserializers in the signal path. This requirement is derived from the concept of defect-based testing: each element in the circuit (whether transistor, passive component, or interconnect) has a target quality requirement; if it is not manufactured to this quality requirement then something - something specific - is wrong. Yet this overall approach is insufficient by itself. It misses the tight coupling of the serial data stream to its internal self-aligned clock. If this clock is too erratic, then perfect serializing or deserializing circuitry will break. Conclusion: production test has two requirements: qualify the clock and qualify the bit generators or extractors. There should be no need for long data streams, or concomitant long test times.

WiMAX technology has emerged as an exciting technology for next generation broadband wireless network with promises to offer high throughput and long coverage. WiMAX, however, has yet to prove its merits when the wireless nodes are not fixed and move at high vehicular speeds. Recent studies suggest that WiMAX offers limited throughput when a mobile node travels at vehicular speeds. Multipath fading causes high bit error rates at the receiver and is considered the main reason behind low throughput at high vehicular speeds. Bit error rates and maximum packet size govern the packet error rates, and error recovery for higher number of corrupted packets is not an attractive option for many real-time applications with tight delay and jitter constraints. In this paper, we present a mathematical model for estimating bit error rates in WiMAX communication at vehicular speeds. The estimated bit error probability is taken into account for proactively computing an optimum packet size that offers the best chance of achieving improved throughput. We further propose a model that can be used to increase the utility of real-time wireless applications (e.g., video surveillance systems in public train) based on the knowledge of estimated transmission rates. We simulated the proposed and other standard schemes for a centralized video surveillance system in a public train where the train moves at high speeds and sends real-time video data to a central control room through wireless channels. The results show that the proposed scheme achieves significantly higher throughput, lower jitter and higher utility gain compared to the standard schemes.

Multiobjective optimization plays an increasingly important role in modern applications, where several criteria are often of equal importance. The task in multiobjective optimization and multiobjective optimal control is therefore to compute the set of optimal compromises (the Pareto set) between the conflicting objectives. The advances in algorithms and the increasing interest in Pareto-optimal solutions have led to a wide range of new applications related to optimal and feedback control, which results in new challenges such as expensive models or real-time applicability. Since the Pareto set generally consists of an infinite number of solutions, the computational effort can quickly become challenging, which is particularly problematic when the objectives are costly to evaluate or when a solution has to be presented very quickly. This article gives an overview of recent developments in accelerating multiobjective optimal control for complex problems where either PDE constraints are present or where a feedback behavior has to be achieved. In the first case, surrogate models yield significant speed-ups. Besides classical meta-modeling techniques for multiobjective optimization, a promising alternative for control problems is to introduce a surrogate model for the system dynamics. In the case of real-time requirements, various promising model predictive control approaches have been proposed, using either fast online solvers or offline-online decomposition. We also briefly comment on dimension reduction in many-objective optimization problems as another technique for reducing the numerical effort.

This paper examines a class of real-time control systems in which each control task triggers its next release based on the value of the last sampled state. Prior work used simulations to demonstrate that self-triggered control systems can be remarkably robust to task delay. This paper derives bounds on a task's sampling period and deadline to quantify how robust the control system's performance will be to variations in these parameters. In particular we establish inequality constraints on a control task's period and deadline whose satisfaction ensures that the closed-loop system's induced L 2 gain lies below a specified performance threshold. The results apply to linear time-invariant systems driven by external disturbances whose magnitude is bounded by a linear function of the system state's norm. The plant is regulated by a full-information H infin controller. These results can serve as the basis for the design of soft real-time systems that guarantee closed-loop control system performance at levels traditionally seen in hard real-time systems.

- Stroke patients often face challenges in communication and independent medication management, necessitating innovative assistive technologies for better healthcare monitoring. This project introduces a real-time hand gesture-based system to monitor tablet intake in stroke patients using computer vision and machine learning techniques. The solution integrates OpenCV for video processing, Media Pipe for accurate hand landmark detection, and Twilio for sending automated SMS alerts to caregivers. The system operates by detecting specific hand gestures-particularly the movement of the index finger toward the mouth-which signifies an attempt to consume medication. When this gesture is confirmed, the system logs the event, updates the tablet count, and triggers both a visual alert using Tkinter and an SMS notification via Twilio. This ensures real-time tracking and caregiver awareness without physical intervention. This low-cost, non-invasive solution can be implemented using a standard webcam and basic hardware, making it especially suitable for home healthcare environments. The methodology enhances patient autonomy while maintaining safety and accountability. Future developments may incorporate deep learning for more robust gesture recognition and extend the system’s functionality to cover broader health monitoring scenarios. Key Words: Hand Gesture Recognition, Stroke Patient Monitoring, Computer Vision, Real-time Alert System. .

The circuit with an output of specified serial data stream has been exposed to the radiated electromagnetic fields generated by indirect discharge from the ElectroStatic Discharge (ESD) simulator. The circuit malfunctioned at a distance of 35 cm from the point of discharge. The ESD transient pulse introduced affected only the data stream and binary counter Integrated Circuit (IC) SN74LS393N was found to be malfunctioning. The counter IC passed the parameter test but failed functionally as all the output pins were malfunctioning. The circuit that failed did not have decoupling capacitors connected to the Vcc supply. Another circuit designed with decoupling capacitors connected to the Vcc supply of all the IC’s has been exposed to indirect ESD air discharge. The effect of the ESD transient pulse on the ones and zeroes of the specified data stream has been observed. The amplitude of the serial data stream has been affected but the order of transmission of the bits has not changed. If the change in amplitude is greater than the set threshold then the order of transmission of bits can change and this becomes critical for sensitive circuits where the set threshold is very small. The decoupling capacitors provided protection against any malfunction of the integrated circuits.

In recent years, consumer electronic devices have been expanding their application domains from traditional consumer electronic devices such as cellular phones, PDAs(Personal Digital Assistants), PMPs(Portable Multimedia Players), Navigation, to Next Generation Personal Computers(NGPCs) such as eating consumer electronic devices, implanted consumer electronic devices, wearable consumer electronic devices. A wearable consumer electronic device is a computer that is subsumed into the personal space of the user, controlled by the user, and is always on and always accessible. Therefore, among the most salient aspect of wearable consumer electronic devices should be small form factor and long battery lifetime. In this paper, we propose a novel low-power real-time operating system (RTOS) specialized for the ARC(Actual Remote Control). An ARC is a wearable wristwatch-type remote controller; it also can serve as a universal remote control for various consumer electronic devices. The proposed RTOS has about 9KB footprints and is equipped with low-power techniques composed of the dynamic power management and the device power management. Experimental results with wearable application show that we can save energy up to 47 % using the proposed low-power techniques.

Intelligent, networked microgrids are becoming increasingly desired for land, sea, and space applications. These self-contained power systems contain limited power availability, but feature two-way communication infrastructure allowing for detailed power measurements and discrete control. Thus, control of individual loads is essential to maintain acceptable system operating conditions. Furthermore, the ability to remotely control these power systems is invaluable when locally enacted control is infeasible. Therefore, developing a system that represents an intelligent microgrid with remote controllability can represent these capabilities, and can be used as tool to test and evaluate ways to address measurement, control, and communication challenges. In order to study the behavior of these systems, a reconfigurable laboratory-based hardware and software microgrid power system was developed, presented, and tested. This system allows for measurement collection and centralized control of remote devices, through an Energy Management System. In the Energy Management System software, collected data is processed using state estimation, which allows for mathematical determination of unknown parameters using a select set of known data. Multiple cases were studied with varying sets of measurement data provided to the estimator. Additionally, two system control cases, composed of remedial voltage control actions, and control actions to meet power demands of critical loads, are presented. During each control action case, the system response is analyzed. Overall, both the measurement and control cases presented successfully demonstrate the system and software capabilities.