Control Code Research Articles

Design and Operation of Internet of Things-Based Monitoring Control System for Induction Machines

The technology of Internet of Things (IoT) can be integrated with systems of electrical machines, for electric drives and wind and solar generation systems, and advance controlling and monitoring. This work presented recent research and progress of electrical drives with IoT technology, regarding design, operation, and trial of the control system for induction motors (ΙΜ). Also, the developed software code and hardware units for speed control were detailed and the results obtained from tests of performance of the ΙΜ integrated with IoT were described. With the IoT integration set-up, the operator can control the frequency values, obtain real-time feedback of the process, and monitor the system during varying loads in steady state. The operation of the ΙΜ system driven by inverter and its monitoring over IoT was proven to have high-accuracy speed control and increased efficiency at supersynchronous speeds. Thus, IoT establishes potentials to become a multipurpose tool in the industrial control of electric drives. This paper established one case study of an IoT set-up and control technique for IM, which is suitable for energy engineering experts in the field of IoT control of industrial equipment.

A DTC-based Fractional-N DPLL using probability-density-shaping spur immunity and Q-noise reduction techniques for IoT applications

A Digital-to-Time Converter based (DTC-based) fractional-N digital phase-locked loop (DPLL) using probability-density-shaping (PDS) spur immunity and quantization phase (Q-noise) reduction techniques is presented. PDS-DSM is used to generate a loop spur immunity control code for DTC. A diff type dither is proposed to further suppress the fractional spur. The loop nonlinearity will not cause fractional spurs if certain conditions are obeyed. Moreover, to reduce the quantization noise, a configurable Phase Interpolator (PI) with 0.125/0.25/0.5/1.0 division step is integrated with a multi-module divider (MMDIV), leading to an 18-dB Q-noise suppression. A reference doubler with duty-cycle correction is adopted to further reduce phase noise. The fractional spurs are greatly mitigated by combining the PDS-DSM and phase interpolator. A DPLL prototype using the aforementioned techniques was designed in a 40-nm standard CMOS process, occupying a 0.99 mm2 silicon area. At a near-integer-N frequency, i.e., near 2.23 GHz, with PDS turned on and off, the post-layout simulated fractional spur is −59 dBc and −20 dBc, respectively. The RMS jitter of the whole chip is 4.218 ps, corresponding to a figure of merit (FOM) of −220.5 dB.

All-digital transmit beamformer for portable high-frequency ultrasound imaging systems.

To meet the requirements of high-frequency ultrasound imaging systems, a transmit-beamforming integrated circuit with higher delay resolution than conventional transmit-beamforming circuits, which are typically implemented using field-programmable gate array chips, is presented. It also requires smaller volumes, allowing for portable applications. Its proposed design includes two all-digital delay-locked loops providing a specified digital control code for a counter-based beamforming delay chain (CBDC) to generate stable and suitable delays for exciting the array transducer elements without variations in process, voltage, and temperature. Moreover, to maintain the duty cycle of long propagation signals, this novel CBDC requires only a few delay cells, significantly reducing hardware costs and power consumption. Simulations were conducted, revealing a maximum time delay of 451.9ns with a time resolution of 652ps and a maximum lateral resolution error of 0.04mm at 6.8mm.

The moderating role of financial managers’ honesty-humility on aggressive financial reporting: evidence from Iran

Purpose The purpose of this study is to investigate the moderating role of honesty-humility of financial managers on aggressive financial reporting behavior. Design/methodology/approach To test the research hypotheses, a scenario-based questionnaire taken from Brink et al. (2018) was used. Using a cross-sectional survey design, the authors collected primary data of 160 financial managers of firms in Iran using structured questionnaires. The research sample selected was based on Cohen et al.’s (2000) table. To test the research hypotheses, analysis of variance was used. Findings The results showed that increasing honesty-humility of financial managers decreases the impact of social pressure and risk appetite interaction on aggressive financial reporting. In addition, the results of further analysis showed that reducing the honesty-humility of financial managers increases the impact of risk appetite on aggressive financial reporting. Moreover, the results indicate that reducing the honesty-humility of financial managers increases the impact of social pressure on aggressive financial reporting. Research limitations/implications This finding provides significant evidence for auditor, managers and policymakers in Iran. Policymakers, auditor and company managers can emphasize compliance with the code of ethics, internal control and corporate governance to increase ethics and reduce negative economic consequences. Originality/value To the best of the authors’ knowledge, this is the first case in an emerging economy to survey the moderating role of honesty-humility of financial managers on aggressive financial reporting behavior. Also, this study contributes to understanding how factors at the individual, social and organizational level combine to influence financial managers’ aggressive financial reporting behavior.

A Mixed Calibration Method of Time-to-Digital Converter for LiDAR Applications

This brief presents a mixed calibration method of time-to-digital converter (TDC) for Light Detection and Ranging (LiDAR) applications, which is primarily implemented by a feedback loop consisting of VCRO-based TDC, double-digital-to-analog converter (DDAC), encoder, sampling circuit, LSB-first algorithm (LSBFA) block, and analog buffer. Based on the external input frequency control code (FCC), the method automatically adjusts the DDAC output to control TDC. To ensure that the DDAC output meets the accuracy requirements, a voltage coverage strategy is proposed, which is implemented by an external code controlling the R-2R array. Furthermore, after the chip operation is stable, a voltage trimming approach is presented to avoid introducing drastic switching activity, which is implemented using an error comparator and an LSBFA block. The peak-to-peak INL and DNL of TDC are 1.81 LSB and 0.44 LSB, respectively.

Synthesis of Robotic System Controllers Using Robotic System Specification Language

Robotic System Specification Language (RSSL) stems from the embodied agent approach to robotic system design. It enables the specification of both the structure and activities of a multi-robot multi-agent robotic system. RSSL specification can be verified and automatically transformed by its compiler into a six-layered Robotic System Hierarchical Petri Net (RSHPN). RSHPN models the activities and structure of the designed robotic system. The automatically generated RSHPN is loaded into RSHPN Tool modeling RSHPNs and automatically generating the controller code. This approach was validated on several robotic systems. The use of RSSL and RSHPN facilitates the synthesis of robotic system controllers.

Model based predictive control strategy for water saving drip irrigation

Traditional irrigation control systems is characterized with inefficient management of water and often results in low water productivity index and reduced cultivation yield. In addition, insufficient water supply and high rate of water loss due to evapotranspiration increases plant stress which often affects its growth and development. Therefore, to address this issues, this paper is aimed at developing a model predictive control (MPC) strategy for water saving drip irrigation experiment that will regulate the soil moisture content within the desired field capacity and above the wilting point, while scheduling irrigation to replace the loss of water from soil and plant due to evapotranspiration in the greenhouse environment. The controller design involves a data driven predictive model identified and integrated with the MPC designer in MATLAB and thereafter exported in Simulink for simulation. The generate controller code was modified and deployed on a Raspberry Pi 4 controller to generate a pulse width modulated signal to drive the pump for the control water mixed with fertilizer. To achieve enhancement of controller an Internet of Things (IoT) integration was used for easy soil, weather, and plant monitoring which are used to update the MPC model for the irrigation control. The performance of the proposed MPC controller deployed drip irrigated Greenhouse(GH1) is benchmarked against an existing automatic evapotranspiration (ETo) model based controller in Greenhouse(GH2), with each greenhouse containing 80 poly bags of Cantaloupe plant with similar growth stage. The results obtained shows that, the proposed MPC-based irrigation system has higher water productivity index of 36.8 g/liters, good quality of fruit with average sweetness level of 13.5 Brix compared to automatic ETo-based irrigation system with 25.6 g/liters and 10.5 Brix, respectively. However, the total mass of harvested fruit for ETo-based irrigation system is higher than MPC-based irrigation system by 21.7%. The performance of the proposed MPC controller was achieved through the integration of event based scheduling with IoT monitoring as well as inclusion of evapotranspiration effect in the plant dynamics.

Transformation von GRAFCET in GAL auf Basis eines ausführlichen Metamodells zur Verifikation von Entwurfsfehlern

Abstract GRAFCET is a graphical means for formal specifications in industrial control design. In order to use these formal specifications for model-driven development of control code, it is beneficial to ensure syntactic correctness and verify the model. This paper presents a detailed meta-model for GRAFCET that includes logical and arithmetic expressions in conditions and assignments. The meta-model and additional invariants allow for creation of syntactically correct Grafcets. On this basis, a translation of GRAFCET into Guarded Action Language (GAL) is presented. The resulting transition systems in GAL allow a semantic analysis of GRAFCET by means of model checking. From these GRAFCET specifications, specification-compliant PLC code can be generated automatically.

Five-Axis Contour Error Control Based on Numerical Control Data

Improving contour accuracy is one of the significant goals of industrial machining. This paper proposes a contour error estimation and compensation algorithm for five-axis computer numerical control (CNC) machine tools based on modified numerical control (NC) codes. The expected path analyzed by NC data and the actual trajectory collected by sensors are spatially mapped by the hidden Markov model (HMM). Next, an evaluation function that hybrids the tool tip position and tool orientation change trend is proposed as the index of contour error estimation. Finally, spatial iterative learning control (ILC) is used to compensate the contour error, and high-precision machining instructions are obtained after multiple iterations. Experiments with different trajectories are performed on a five-axis platform to verify the proposed algorithm’s effectiveness. The results show that the proposed algorithm without using planned trajectories, has the same good control effect as traditional methods, which must know the planning trajectory for simple trajectories. At the same time, the method proposed in this paper has better performance than existing algorithms based on tool tip position nearest principle at sharp corners. In conclusion, on the basis of not depending on the planning trajectories, this method has a better compensation effect for the overall accuracy of trajectories and is easier to implement in industrial applications.

Theoretical research and maintenance of electro hydraulically controlled injectors

Introduction. Nowadays the part of the diesel engines for KamAZ-740 cars are operated with fuel equipment, in which the injectors have hydro mechanical control. Their main disadvantage is the low fuel pressure in front of the injector openings (less than 60 MPa) and the lack of fuel supply control.The use of injectors with electro hydraulic control (EHC) increases the pressure in the injector cavity up to 250 MPa and control the fuel injection process. The disadvantage of the injectors with EHC is a structural complexity of a control valve, the difficulty of its regulation and coding. The object of the study is the injectors of KamAZ-740 diesel engine with electro hydraulic control of the atomizer needle stroke.The purpose of this work is to carry out theoretical research and improve the methods of maintenance of injectors with electro hydraulic control (control valve regulation and coding), which will increase their reliability, durability and ensure a reduction in diesel fuel consumption.Research methods. The study of the nozzle control valve is theoretical and calculated. The paper proposes a calculation method and performs theoretical studies for the influence of pressure (50 – 250 MPa) on the value of the effective flow section and the diameter of the nozzle holes of the sprayer.For the injectors with EHC, the control valve regulation procedure has been clarified, which consists in the fact that at the beginning of regulation, the main force acting on the ball from the side of the maximum pressure in the control chamber (for example, 200 MPa) equal to 76 N is calculated (see Figure 4). Then the required spring force of 100 N is determined (20-40% more, see Figure 5). Next, the strength of the electromagnet is estimated at 140 N (20 – 40% more of the spring force, see Figure 6).The results of theoretical research. The results of computational (theoretical) studies for the effective flow section of the sprayer and the diameter of the nozzle holes, depending on the pressure P in front of the nozzle holes, are presented.The paper defines. 1. The forces acting on the ball (57 – 105 N) depending on the pressure in the control chamber (150 – 275 MPa). 2. Spring forces (40 – 140 N) with a stiffness of 40 N /mm, depending on its compression up to 3.5 mm. 3. The forces of the electromagnet (140 – 20 N) depending on the gap between the anchor and the core (0.2 – 0.5 mm).The method of restoring the required (rated) cyclic fuel supply when it changes as a result of replacing the control valve or adjusting is considered. The calculated values of fuel supply per cycle (mm3/cycle) from the activation time are given.Conclusion. The results of the study are intended for organizations and enterprises engaged in diagnostics, restoration, adjustment and coding of injectors with electro hydraulic control for the needle stroke of sprayers. The results of computational studies can be used to refine the methodology of maintenance of fuel systems with electronic control (Common Rail).

Surveillance Creep in Times of Crisis: The Alipay Health Code and Implications for Privacy, Civil Liberties, and Social Control

Surveillance Creep in Times of Crisis: The Alipay Health Code and Implications for Privacy, Civil Liberties, and Social Control

Deletions and Insertions of the Symbol “0” and Asymmetric/Unidirectional Error Control Codes for the L Metric

This paper gives some theory and efficient design of binary block codes capable of controlling the deletions of the symbol “0” (referred to as 0-deletions) and/or the insertions of the symbol “0” (referred to as 0-insertions). This problem of controlling 0-deletions and/or 0-insertions (referred to as 0-errors) is shown to be equivalent to the efficient design of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{1}$ </tex-math></inline-formula> metric asymmetric error control codes over the natural alphabet, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathbf{I}}\!{\mathbf{I}}\!\!{\mathbf{N}}$ </tex-math></inline-formula> . In this way, it is shown that the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t 0$ </tex-math></inline-formula> -insertion correcting codes are actually capable of controlling much more; namely, they can correct <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t 0$ </tex-math></inline-formula> -errors, detect <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(t+1)\,\,0$ </tex-math></inline-formula> -errors and, simultaneously, detect all occurrences of only 0-deletions or only 0-insertions in every received word (briefly, they are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t$ </tex-math></inline-formula> -Symmetric 0-Error Correcting/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(t+1)$ </tex-math></inline-formula> -Symmetric 0-Error Detecting/All Unidirectional 0-Error Detecting ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t$ </tex-math></inline-formula> -Sy0EC/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(t+1)$ </tex-math></inline-formula> -Sy0ED/AU0ED) codes). From the relations with the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{1}$ </tex-math></inline-formula> distance error control codes, new improved bounds are given for the optimal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t 0$ </tex-math></inline-formula> -error correcting codes. Optimal non-systematic code designs are given. Decoding can be efficiently performed by algebraic means using the Extended Euclidean Algorithm (EEA).

Adding RLL Properties to Four CCSDS LDPC Codes without Increasing Their Redundancy

This paper presents the construction of Run Length Limited (RLL) Error Control Codes (ECCs) from four Low Density Parity Check (LDPC) Codes specified by Consultative Committee for Space Data Systems (CCSDS). The obtained RLL-ECCs present a practical alternative to the CCSDS codes with pseudo-randomizers. Their advantage is that the maximal runlengths of equal symbols in their codeword sequences are guaranteed, which is not the case if the common approach with pseudo-randomizers is used. The other advantages are that no additional redundancy is introduced into encoded codewords and that the encoding and decoding procedures of the original error control CCSDS codes do not have to be modified in the following cases. In the first case if hard decoding is used and the transmission channel can be modeled as a Binary Symmetric Channel (BSC) or in the second case if soft decoding and coherent Binary Phase Shift Keying (BPSK) modulation is used and the appropriate transmission channel model is an Additive White Gaussian Noise (AWGN) channel.

Stabilizing Error-Correction Codes for Control Over Erasure Channels

In this article, we propose <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(k,k^{\prime })$</tex-math></inline-formula> stabilizing codes, which are a type of delayless error-correction codes that are useful for control over networks with erasures. For each input symbol, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k$</tex-math></inline-formula> output symbols are generated by the stabilizing code. Receiving at least <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k^{\prime }$</tex-math></inline-formula> of these outputs guarantees stability. Thus, both the system to be stabilized and the channel are taken into account in the design of the erasure codes. Receiving more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k^{\prime }$</tex-math></inline-formula> outputs further improves the performance of the system. In the case of i.i.d. erasures, we further demonstrate that the erasure code can be constructed such that stability is achieved if on average at least <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k^{\prime }$</tex-math></inline-formula> output symbols are received. Our focus is on linear and time-invariant systems, and we construct codes based on independent encodings and multiple descriptions. Stability is assessed via Markov jump linear system theory. The theoretical efficiency and performance of the codes are assessed, and their practical performances are demonstrated in a simulation study. There is a significant gain over other delayless codes such as repetition codes.

Run length limited CCSDS convolutional codes for optical communications

Abstract This paper presents the construction of RLL-ECCs (run length limited error control codes) from three selected ECCs specified by Consultative Committee for Space Data Systems (CCSDS) for optical communications. The RLL-ECCs obtained present a practical alternative to CCSDS codes with pseudo-randomizers. Their advantage is that the maximal run lengths of equal symbols in their codeword sequences are guaranteed, which is not the case if the common approach with pseudo-randomizers is used. The other advantages are that no additional redundancy is introduced into encoded codewords and that the encoding and decoding procedures of the original error control CCSDS codes do not have to be modified in the following cases: Firstly, if hard decoding is used and the transmission channel can be modeled as a BSC (binary symmetric channel) and secondly, if soft decoding and coherent BPSK (binary phase shift keying) modulation is used and the appropriate transmission channel model is an AWGN (additive white Gaussian noise) channel.

A nascent peptide code for translational control of mRNA stability in human cells

Stability of eukaryotic mRNAs is associated with their codon, amino acid, and GC content. Yet, coding sequence motifs that predictably alter mRNA stability in human cells remain poorly defined. Here, we develop a massively parallel assay to measure mRNA effects of thousands of synthetic and endogenous coding sequence motifs in human cells. We identify several families of simple dipeptide repeats whose translation triggers mRNA destabilization. Rather than individual amino acids, specific combinations of bulky and positively charged amino acids are critical for the destabilizing effects of dipeptide repeats. Remarkably, dipeptide sequences that form extended β strands in silico and in vitro slowdown ribosomes and reduce mRNA levels in vivo. The resulting nascent peptide code underlies the mRNA effects of hundreds of endogenous peptide sequences in the human proteome. Our work suggests an intrinsic role for the ribosome as a selectivity filter against the synthesis of bulky and aggregation-prone peptides.

Natural Language Processing Application on Commit Messages: A Case Study on HEP Software

Version Control and Source Code Management Systems, such as GitHub, contain a large amount of unstructured historical information of software projects. Recent studies have introduced Natural Language Processing (NLP) to help software engineers retrieve information from a very large collection of unstructured data. In this study, we have extended our previous study by increasing our datasets and machine learning and clustering techniques. We have followed a complex methodology made up of various steps. Starting from the raw commit messages we have employed NLP techniques to build a structured database. We have extracted their main features and used them as input of different clustering algorithms. Once each entry was labelled, we applied supervised machine learning techniques to build a prediction and classification model. We have developed a machine learning-based model to automatically classify commit messages of a software project. Our model exploits a ground-truth dataset that includes commit messages obtained from various GitHub projects belonging to the High Energy Physics context. The contribution of this paper is two-fold: it proposes a ground-truth database and it provides a machine learning prediction model that automatically identifies the more change-prone areas of code. Our model has obtained a very high average accuracy (0.9590), precision (0.9448), recall (0.9382), and F1-score (0.9360).

RESEARCH OF THE CONVERTING STAGES FOR THE VOLUME MODEL OF THE PRODUCT INTO THE CONTROL CODE FOR A 3D PRINTER IN THE CONTEXT OF AUTOMATED CONSTRUCTION OF 3D PRINTING TECHNOLOGY

Problem statement. The integration of the latest technologies in the field of software at the stages of construction appears as one of the main tasks for designers. Creating objects based on 3D printing technology requires the use of appropriate high-tech solutions. One of these solutions is the analysis of the converting process a three-dimensional model into a control code for 3D printing − it is precisely from this analysis that the degree of construction efficiency for building structures by the 3D printing method depends. The purpose of the article. Based on the analysis of 3D printing concepts and modern software, form a conceptual diagram of the converting stages for the product three-dimensional model into a control code for 3D printers. Determine shortcomings that can complicate the implementation of this process. Conclusions. The working process of 3D printing is complex and requires in-depth knowledge of both the software and hardware of the system as a whole. A detailed study of this issue will further optimize the planning of construction processes, which in turn plays an important role in the overall efficiency of the 3D printing system. The use of 3D computer graphics programs may not include models’ specific features that will be key importance for 3D printing. Surface tessellation done in CAD for modeling often ends up with errors in the *.STL data structure in the form of gaps and holes, resulting in open loops in cross-sections that cannot be fabricated as layers in practice. When converting 3D models to *.STL format automatically, with the help of specialized software packages, you should take the time to thoroughly check the STL format. G-code is the first step towards understanding the digital software control of a 3D printer. It can be generated automatically, which can lead to a large number of errors. At the converting stage of the 3D model into *.STL format and in the direct process of G-code generation, highly qualified interdisciplinary specialists who are able to combine these technologies in practice.

Spatial microscopic modeling of collective movements in multi-robot systems: Design choices and calibration.

Despite the strong increase in available computational power enabling an unprecedented level of realism in simulation, modeling robotic systems at higher abstraction level remains crucial to efficiently design robot controllers and analyze their properties. This is especially true for multi-robot systems, with their high computational complexity due to the numerous interactions among individual robots. While multiple contributions in the literature have proposed approaches leading to highly abstracted and therefore computationally efficient models, often such abstractions have been obtained with strong assumptions on the underlying spatiality of the system behavior (e.g., well-mixed system, diffusive system). In this work, we address the modeling of an arbitrary collective movement involving the displacement of a robot ensemble along a certain trajectory overlapped with continuous interactions among the robotic members. Without loss of generality, we have focused our modeling effort on a flocking case study, as a prominent and well-known example of collective movement. We investigate our case study at the microscopic level while leveraging a more faithful submicroscopic model (implemented through a high-fidelity robotic simulator) as ground-truth. More specifically, we illustrate multiple choices for designing and calibrating such microscopic models, so that their faithfulness with the underlying submicroscopic model of the same physical system is preserved. Such effort has produced concrete implementations of three different microscopic models for the same case study, all taking into account the spatiality of the collective movement. We find that all three microscopic models produce quantitatively accurate estimations for our flocking case study. As they rely on different underlying assumptions and modeling techniques, the choice between them is a trade-off between the computational cost, the modeling effort, the metrics considered to evaluate their faithfulness, and the subsequent usage (e.g., control design, system property analysis, control code prototyping).

Security Analysis for Distributed IoT-Based Industrial Automation

Internet of Things (IoT) technologies enable development of reconfigurable manufacturing systems—a new generation of modularized industrial equipment suitable for highly customized manufacturing. Sequential control in these systems is largely based on discrete events, whereas their formal execution semantics is specified as control interpreted Petri nets (CIPN). Despite industry-wide use of programming languages based on the CIPN formalism, formal verification of such control applications in the presence of adversarial activity is not supported. Consequently, in this article, we introduce security-aware modeling and verification techniques for CIPN-based sequential control applications. Specifically, we show how CIPN models of networked industrial IoT controllers can be transformed into time Petri net (TPN)-based models and composed with plant and security-aware channel models in order to enable system-level verification of safety properties in the presence of network-based attacks. Additionally, we introduce realistic channel-specific attack models that capture adversarial behavior using nondeterminism. Moreover, we show how verification results can be utilized to introduce security patches and facilitate design of attack detectors that improve system resiliency and enable satisfaction of critical safety properties. Finally, we evaluate our framework on an industrial case study. Note to Practitioners—Our main goal is to provide formal security guarantees for distributed sequential controllers. Specifically, we target smart automation controllers geared toward Industrial IoT applications that are typically programed in C/C++ and are running applications originally designed in, for example, GRAFCET (IEC 60848)/SFC (IEC 61131-3) automation programming languages. Since existing tools for the design of distributed automation do not support system-level verification of relevant safety properties, we show how security-aware transceiver and communication models can be developed and composed with distributed controller models. Then, we show how existing tools for verification of time Petri nets can be used to verify relevant properties including safety and liveness of the distributed automation system in the presence of network-based attacks. To provide an end-to-end analysis as well as security patching, results of our analysis can be used to deploy suitable firmware updates during the stage when executable code for target controllers (e.g., in C/C++) is generated based on GRAFCET/SFC control models. We also show that security guarantees can be improved as the relevant safety/liveness properties can be verified after corresponding security patches are deployed. Finally, we show applicability of our framework on a realistic distributed pneumatic manipulator.