| 1. |
- Blanch, Krister, 1991
(author)
-
Beyond-application datasets and automated fair benchmarking
- 2023
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Licentiate thesis (other academic/artistic)abstract
- Beyond-application perception datasets are generalised datasets that emphasise the fundamental components of good machine perception data. When analysing the history of perception datatsets, notable trends suggest that design of the dataset typically aligns with an application goal. Instead of focusing on a specific application, beyond-application datasets instead look at capturing high-quality, high-volume data from a highly kinematic environment, for the purpose of aiding algorithm development and testing in general. Algorithm benchmarking is a cornerstone of autonomous systems development, and allows developers to demonstrate their results in a comparative manner. However, most benchmarking systems allow developers to use their own hardware or select favourable data. There is also little focus on run time performance and consistency, with benchmarking systems instead showcasing algorithm accuracy. By combining both beyond-application dataset generation and methods for fair benchmarking, there is also the dilemma of how to provide the dataset to developers for this benchmarking, as the result of a high-volume, high-quality dataset generation is a significant increase in dataset size when compared to traditional perception datasets. This thesis presents the first results of attempting the creation of such a dataset. The dataset was built using a maritime platform, selected due to the highly dynamic environment presented on water. The design and initial testing of this platform is detailed, as well as as methods of sensor validation. Continuing, the thesis then presents a method of fair benchmarking, by utilising remote containerisation in a way that allows developers to present their software to the dataset, instead of having to first locally store a copy. To test this dataset and automatic online benchmarking, a number of reference algorithms were required for initial results. Three algorithms were built, using the data from three different sensors captured on the maritime platform. Each algorithm calculates vessel odometry, and the automatic benchmarking system was utilised to show the accuracy and run-time performance of these algorithms. It was found that the containerised approach alleviated data management concerns, prevented inflated accuracy results, and demonstrated precisely how computationally intensive each algorithm was.
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| 2. |
- Westin, Jonathan, 1980, et al.
(author)
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Digitising Sensitive Heritage Monuments In Antarctica
- 2024
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In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLVIII-2/W4-2024. 10th International Workshop 3D-ARCH "3D Virtual Reconstruction and Visualization of Complex Architectures, 21–23 February 2024, Siena, Italy / editor(s): S. Campana, F. Fassi, and F. Remondino. - : International Society for Photogrammetry and Remote Sensing. - 1682-1750.
-
Conference paper (peer-reviewed)abstract
- During the Antarctica expedition CHAQ2020, several cultural heritage sites – remains from the Swedish South Polar Expedition (1901–1903) – were documented using a range of different techniques and technologies. These physical monuments and environments are for all intents and purposes unavailable for most researchers due to their remote location and are also threatened by the effects of climate change. Hence, the deployed documentation techniques and technologies were selected both as a consequence of the inherently difficult conditions in Antarctica, where their reliance, durability, and speed were key considerations, but also for their perceived ability to document the unique and fragile environment. The documentation was carried out with the double intention of both allowing for observations in situ through processes of analytical drawings and data capture, but also capturing the environment as broadly and deeply as possible, in essence making a copy of it open for studies of unknown unknowns, that could serve as a source material for research questions still undefined. Hence, with the documentation of the winter station on Snow Hill Island as a case study, and with a perspective on documentation as a method through which to process, preserve, and disseminate information, this article serves to critically detail, compare, and evaluate the digital techniques and technologies that the expedition deployed to capture architectural elements and spatial contexts, and the data that could be obtained through these.
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| 3. |
- Theorin, Alfred, et al.
(author)
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An event-driven manufacturing information system architecture for Industry 4.0
- 2017
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In: International Journal of Production Research. - : Taylor & Francis. - 0020-7543 .- 1366-588X. ; 55:5, s. 1297-1311
-
Research review (peer-reviewed)abstract
- Future manufacturing systems need to be more flexible, to embrace tougher and constantly changing market demands. They need to make better use of plant data, ideally utilising all data from the entire plant. Low-level data should be refined to real-time information for decision-making, to facilitate competitiveness through informed and timely decisions. The Line Information System Architecture (LISA), is presented in this paper. It is an event-driven architecture featuring loose coupling, a prototype-oriented information model and formalised transformation services. LISA is designed to enable flexible factory integration and data utilisation. The focus of LISA is on integration of devices and services on all levels, simplifying hardware changes and integration of new smart services as well as supporting continuous improvements on information visualisation and control. The architecture has been evaluated on both real industrial data and industrial demonstrators and it is also being installed at a large automotive company. This article is an extended and revised version of the paper presented at the 2015 IFAC Symposium on Information Control in Manufacturing (INCOM 2015). The paper has been restructured in regards to the order and title of the chapters, and additional information about the integration between devices and services aspects have been added. The introduction and the general structure of the paper now better highlight the contributions of the paper and the uniqueness of the framework.
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| 4. |
- Xie, Haotian, et al.
(author)
-
Robust parallel predictive torque control with model reference adaptive estimator for im drives
- 2020
-
In: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. ; 23 August 2020, s. 1219-1224
-
Conference paper (peer-reviewed)abstract
- This paper presents the robustness improvement for the proposed parallel structure predictive torque control (PPTC) via a MRA-based estimator. Although predictive torque control (PTC) has the merits of lower switching frequency and straightforward implementation, it inevitably suffers from the inherent drawbacks of high torque ripple and inappropriate tuning of the weighting parameter. To solve this issue, the proposed PPTC employs two homogeneous objective terms which are optimized in a parallel strucutre, to bypass the usage of weighting parameters. However, the parameter mismatches in the control plant will lead to the prediction torque and flux error, which further impacts the control behavior of the system. Therefore, this paper evaluates the parameter sensitivity for PPTC, aiming to improve robustness of the proposed algorithm with a MRA-based parameter estimator. Finally, the validity of the proposed scheme is confirmed through an experimental assessment.
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| 5. |
- Yin, Hang, et al.
(author)
-
Policy Learning with Embedded Koopman Optimal Control
-
Other publication (other academic/artistic)abstract
- Embedding an optimization process has been explored for imposing efficient and flexible policy structures. Existing work often build upon nonlinear optimization with explicitly unrolling of iteration steps, making policy inference prohibitively expensive for online learning and real-time control. Our approach embeds a linear-quadratic-regulator (LQR) formulation with a Koopman representation, thus exhibiting the tractability from a closed-form solution and richness from a non-convex neural network. We use a few auxiliary objectives and reparameterization to enforce optimality conditions of the policy that can be easily integrated to standard gradient-based learning. Our approach is shown to be effective for learning policies rendering an optimality structure and efficient reinforcement learning, including simulated pendulum control, 2D and 3D walking, and manipulation for both rigid and deformable objects. We also demonstrate real world application in a robot pivoting task.
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| 6. |
- Ge, Yu, 1995, et al.
(author)
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5G SLAM Using the Clustering and Assignment Approach with Diffuse Multipath
- 2020
-
In: Sensors. - : MDPI AG. - 1424-8220. ; 20:16, s. 1-31
-
Journal article (peer-reviewed)abstract
- 5G communication systems operating above 24 GHz have promising properties for user localization and environment mapping. Existing studies have either relied on simplified abstract models of the signal propagation and the measurements, or are based on direct positioning approaches, which directly map the received waveform to a position. In this study, we consider an intermediate approach, which consists of four phases-downlink data transmission, multi-dimensional channel estimation, channel parameter clustering, and simultaneous localization and mapping (SLAM) based on a novel likelihood function. This approach can decompose the problem into simpler steps, thus leading to lower complexity. At the same time, by considering an end-to-end processing chain, we are accounting for a wide variety of practical impairments. Simulation results demonstrate the efficacy of the proposed approach.
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| 7. |
- Liu, Yang, et al.
(author)
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A Study Towards Reliability- and Delay-Critical Wireless Communication for RoboCup Robotic Soccer Application
- 2007
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In: 2007 International Conference on Wireless Communications, Networking and Mobile Computing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1424413117 - 9781424413119 - 1424413125 - 1424413125 - 1424413117 ; , s. 633-636
-
Conference paper (peer-reviewed)abstract
- RoboCup is an international competition for a team of multiple fast-moving robots under a dynamic environment to autonomously play soccer game against another team. Due to the nature of the competition, the requirements and constraints for the wireless communication are extremely tight. The challenge is that wireless communication is involved in the control loop and therefore the reliability and propagation delay are vital factors which directly affect the team performance. Beside, various interferences with known and unknown frequency / transmission power usually exist at the competition site, which are hazardous environment to achieve reliable and low latency performance for wireless communication. This paper investigates the performance strengths and weaknesses of wireless communication means e.g. RF, IEEE 802.11a/b, IEEE 802.15.4, DECT, Linx, etc, which are commonly used nowadays in different RoboCup teams and propose improvements towards reliable and delay-critical wireless communication.
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| 8. |
- Ortiz Morales, Daniel, 1984-, et al.
(author)
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Path-constrained motion analysis : an algorithm to understand human performance on hydraulic manipulators
- 2015
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In: IEEE Transactions on Human-Machine Systems. - 2168-2291. ; 45:2, s. 187-199
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Journal article (peer-reviewed)abstract
- We propose a novel method to analyze how human operators use hydraulic manipulators of heavy-duty equipment. The approach is novel in the sense that it applies knowledge of motion planning and optimization techniques used in robotics. As an example, we consider the case of operating a forestry crane. To that end, we use motion data that has been recorded during standard operation with the help of sensors and a data acquisition unit. The data backs up the notion that operators work by performing repeatable patterns observed in the trajectories of the manipulator's joints. We show how this nominal behavior is computed, and consequently this allow us to present the following: 1) an analytical procedure to analyze motions, 2) how to represent the "performance" of the operator in a 2D plot, 3) an example of how to use this information to suggest customized control settings, and 4) some complementary ideas needed for improving efficiency through automation.
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| 9. |
- Rahal, Moustafa, et al.
(author)
-
RIS-Enabled NLoS Near-Field Joint Position and Velocity Estimation under User Mobility
- 2024
-
In: IEEE Journal on Selected Topics in Signal Processing. - 1941-0484 .- 1932-4553. ; In Press
-
Journal article (peer-reviewed)abstract
- In the context of single-(BS) nonline- of-sight (NLoS) single-epoch localization with the aid of a reflective (RIS), this paper introduces a novel three-step algorithm that jointly estimates the position and velocity of a mobile (UE), while compensating for the Doppler effects observed in (NF) at the (RIS) elements over the short transmission duration of a sequence of (DL) pilot symbols. First, a low-complexity initialization procedure is proposed, relying in part on (FF) approximation and a static user assumption. Then, an alternating optimization procedure is designed to iteratively refine the velocity and position estimates, as well as the channel gain. %, at every step along the way. The refinement routines leverage small angle approximations and the linearization of the (RIS) response, accounting for both NF and mobility effects. We evaluate the performance of the proposed algorithm through extensive simulations under diverse operating conditions with regard to (SNR), (UE) mobility, uncontrolled multipath and (RIS)-(UE) distance. %We evaluate the performance of the proposed algorithm by means of simulations in a canonical scenario and Our results reveal remarkable performance improvements over the (SoTA) mobility-agnostic benchmark algorithm, while indicating convergence of the proposed algorithm to respective theoretical bounds on position and velocity estimation. %[BD: I remember we had this discussion with CHAL about the use of Algo1 as a variant of an existing algo (in 1st approximation). Does it still hold?], illustrating the dominating impact of the distance to the (RIS), as well as of (UE) velocity.
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| 10. |
- Behdadi, Dorna, 1988, et al.
(author)
-
A Normative Approach to Artificial Moral Agency
- 2020
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In: Minds and Machines. - : Springer Science and Business Media LLC. - 0924-6495 .- 1572-8641. ; 30:2, s. 195-218
-
Journal article (peer-reviewed)abstract
- This paper proposes a methodological redirection of the philosophical debate on artificial moral agency (AMA) in view of increasingly pressing practical needs due to technological development. This “normative approach” suggests abandoning theoretical discussions about what conditions may hold for moral agency and to what extent these may be met by artificial entities such as AI systems and robots. Instead, the debate should focus on how and to what extent such entities should be included in human practices normally assuming moral agency and responsibility of participants. The proposal is backed up by an analysis of the AMA debate, which is found to be overly caught in the opposition between so-called standard and functionalist conceptions of moral agency, conceptually confused and practically inert. Additionally, we outline some main themes of research in need of attention in light of the suggested normative approach to AMA.
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| 11. |
- Krook, Jonas, 1986
(author)
-
Formal Methods and Safety for Automated Vehicles: Modeling, Abstractions, and Synthesis of Tactical Planners
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- One goal of developing automated road vehicles is to completely free people from driving tasks. Automated vehicles with no human driver must handle all traffic situations that human drivers are expected to handle, possibly more. Though human drivers cause a lot of traffic accidents, they still have a very low accident and failure rate that automated vehicles must match. Tactical planners are responsible for making discrete decisions for the coming seconds or minutes. As with all subsystems in an automated vehicle, these planners need to be supported with a credible and convincing argument of their correctness. The planners interact with other road users in a feedback loop, so their correctness depends on their behavior in relation to other drivers and road users over time. One way to ascertain their correctness is to test the vehicles in real traffic. But to be sufficiently certain that a tactical planner is safe, it has to be tested on 255 million miles with no accidents. Formal methods can, in contrast to testing, mathematically prove that given requirements are fulfilled. Hence, these methods are a promising alternative for making credible arguments for tactical planners’ correctness. The topic of this thesis is the use of formal methods in the automotive industry to design safe tactical planners. What is interesting is both how automotive systems can be modeled in formal frameworks, and how formal methods can be used practically within the automotive development process. The main findings of this thesis are that it is viable to formally express desired properties of tactical planners, and to use formal methods to prove their correctness. However, the difficulty to anticipate and inspect the interaction of several desired properties is found to be an obstacle. Model Checking, Reactive Synthesis, and Supervisory Control Theory have been used in the design and development process of tactical planners, and these methods have their benefits, depending on the application. To be feasible and useful, these methods need to operate on both a high and a low level of abstraction, and this thesis contributes an automatic abstraction method that bridges this divide. It is also found that artifacts from formal methods tools may be used to convincingly argue that a realization of a tactical planner is safe, and that such an argument puts formal requirements on the vehicle’s other subsystems and its surroundings.
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| 12. |
- La Hera, Pedro
(author)
-
Non-linear dynamics modelling description for simulating the behaviour of forestry cranes
- 2014
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In: International Journal of Modelling, Identification and Control. - : Inderscience Publishers. - 1746-6172 .- 1746-6180. ; 21, s. 125 - 138
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Journal article (peer-reviewed)abstract
- Model-based design is a standard framework widely adopted in modern industry. It is used for designing multi-domain engineering solutions based on computer-aided simulation technology. Currently, this approach is also being considered as a tentative method for designing modern heavy-duty machine technology. Under this motivation, our aim is to present how modelling techniques can be used for simulating dynamics of forestry machines. To this end, we consider a forestry crane, and propose mathematical models and calibration techniques, such that model-based methods can subsequently be applied. The complexity of the machine is represented by first principle laws, in which the mechanical system is modelled by Euler-Lagrange formulations, and the hydraulic system is modelled by principles of fluid dynamics. The calibration algorithms are performed by statistical algorithms based on linear and non-linear least-squares methods. The results of simulation show a significant correspondence between the simulated and observed variables, validating our procedures.
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| 13. |
- Nielsen, Stig Anton, 1981, et al.
(author)
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Propositional Architecture using Induced Representation
- 2014
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In: What’s the Matter? Materiality and Materialism at the Age of Computation. - 9789608932067 ; , s. 297-312
-
Conference paper (peer-reviewed)abstract
- The paper describes a method and an approach to using sensor data, machine-learning and pattern recognition for proposing and guiding immediate modifications to the existing built environment. The proposed method; Induced Representation, consists of a few steps which we have identified as crucial for such an approach. The steps are A: data collection from the environment, B: machine cognition, learning, prediction, and, c: proposition, visualization, and embodied representations for quick implementation. In the paper we outline the factual and theoretical basis for this approach, and we present and discuss three experiments that each deal with the steps A, B and C.
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| 14. |
- Rosenstatter, Thomas, et al.
(author)
-
Modelling the Level of Trust in a Cooperative Automated Vehicle Control System
- 2018
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In: IEEE transactions on intelligent transportation systems (Print). - Piscataway, NJ : IEEE Press. - 1524-9050 .- 1558-0016. ; 19:4, s. 1267-1247
-
Journal article (peer-reviewed)abstract
- Vehicle-to-vehicle communication is a key technology for achieving increased perception for automated vehicles, where the communication enables virtual sensing by means of sensors in other vehicles. In addition, this technology also allows detection and recognition of objects that are out-of-sight. This paper presents a trust system that allows a cooperative and automated vehicle to make more reliable and safe decisions. The system evaluates the current situation and generates a trust index indicating the level of trust in the environment, the ego vehicle, and the surrounding vehicles. This research goes beyond secure communication and concerns the verification of the received data on a system level. The results show that the proposed method is capable of correctly identifying various traffic situations and how the trust index is used while manoeuvring in a platoon merge scenario.
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| 15. |
- Selvaraj, Yuvaraj, 1990
(author)
-
On Provably Correct Decision-Making for Automated Driving
- 2020
-
Licentiate thesis (other academic/artistic)abstract
- The introduction of driving automation in road vehicles can potentially reduce road traffic crashes and significantly improve road safety. Automation in road vehicles also brings several other benefits such as the possibility to provide independent mobility for people who cannot and/or should not drive. Many different hardware and software components (e.g. sensing, decision-making, actuation, and control) interact to solve the autonomous driving task. Correctness of such automated driving systems is crucial as incorrect behaviour may have catastrophic consequences. Autonomous vehicles operate in complex and dynamic environments, which requires decision-making and planning at different levels. The aim of such decision-making components in these systems is to make safe decisions at all times. The challenge of safety verification of these systems is crucial for the commercial deployment of full autonomy in vehicles. Testing for safety is expensive, impractical, and can never guarantee the absence of errors. In contrast, formal methods , which are techniques that use rigorous mathematical models to build hardware and software systems can provide a mathematical proof of the correctness of the system. The focus of this thesis is to address some of the challenges in the safety verification of decision-making in automated driving systems. A central question here is how to establish formal verification as an efficient tool for automated driving software development. A key finding is the need for an integrated formal approach to prove correctness and to provide a complete safety argument. This thesis provides insights into how three different formal verification approaches, namely supervisory control theory, model checking, and deductive verification differ in their application to automated driving and identifies the challenges associated with each method. It identifies the need for the introduction of more rigour in the requirement refinement process and presents one possible solution by using a formal model-based safety analysis approach. To address challenges in the manual modelling process, a possible solution by automatically learning formal models directly from code is proposed.
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| 16. |
- Theorin, Alfred, et al.
(author)
-
An Event-Driven Manufacturing Information System Architecture
- 2015
-
In: 15th IFAC Symposium onInformation Control Problems inManufacturing - INCOM 2015. - : Elsevier BV. ; 48:3, s. 547-554
-
Conference paper (peer-reviewed)abstract
- Future manufacturing systems need to be more flexible, to embrace tougher and constantly changing market demands. They also need to make better use of plant data, ideally utilizing all data from the entire plant. Low-level data should be refined to real-time information for decision making, to facilitate competitiveness through informed and timely decisions. The Line Information System Architecture, LISA, is designed to enable flexible factory integration and data utilization. In LISA, international standards and established off-the-shelf technologies have been combined with the main objective to be industrially applicable. LISA is an event-driven architecture with a prototype-oriented information model and formalized transformation services. It features loose coupling, flexibility, and ease of retrofitting legacy devices. The architecture has been evaluated on both real industrial data and industrial demonstrators and is also being installed at a large automotive company.
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| 17. |
- Bian, Xiaolei, et al.
(author)
-
A Novel Model-based Voltage Construction Method for Robust State-of-health Estimation of Lithium-ion Batteries
- 2021
-
In: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 68:12, s. 12173-12184
-
Journal article (peer-reviewed)abstract
- Accurate estimation of the state-of-health (SOH) is vital to the life management of lithium-ion batteries (LIBs). This paper proposes a fusion-type SOH estimation method by combining the model-based feature extraction and data-based state estimate. Particularly, a novel model-based voltage construction method is proposed to eliminate the unfavorable numerical condition and reshape the disturbance-free incremental capacity (IC) curves. Leveraging the modified IC curves, a set of informative features-of-interest are extracted and evaluated, while eventually several cautiously-selected ones are used to estimate the SOH of LIB accurately. Furthermore, the impact of model order on the estimation performance is scrutinized, to give insights into the parameterization in practical applications. Long-term cycling tests on different types of LIB cells are used for evaluation. The proposed method is validated with a good robustness to the cell inconsistency, temperature uncertainty, noise corruption, and a satisfied generality to different battery chemistries.
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| 18. |
- Donde, Shrinish
(author)
-
Optimal Robot Localisation Techniques for Real World Scenarios
- 2019
-
Conference paper (other academic/artistic)abstract
- The following paper is a thorough review of our research based on the localisation of robots. It is an attempt to segregate the techniques, to locate the accurate position of robots in different environments and to discuss the superlative methods to localise such robots or in some cases an unmanned vehicle. The paper is divided into three real world problem statements and a thorough analysis of the best technique amongst other is made, for all the three conditions namely underwater, indoor and space, based on a number of parameters such as the cost, accuracy, efficiency, implementation of the technique and the environmental conditions around the robot. The primary reason to select these problem statements is due to the recent trends of research in these domains. Each of the technique has been chosen after discarding several previously applied techniques and an effective approach has been put forward for localising the robots in different areas.
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| 19. |
- Farhadi, Hamed, 1983, et al.
(author)
-
An adaptive localization technique for wireless capsule endoscopy
- 2016
-
In: International Symposium on Medical Information and Communication Technology, ISMICT. - : IEEE Computer Society. - 2326-8301 .- 2326-828X. - 9781509028498
-
Conference paper (peer-reviewed)abstract
- Wireless capsule endoscopy (WCE) is an emerging technique to enhance Gastroenterologists information about the patient's gastrointestinal (G.I.) tract. Localization of capsule inside human body in this case is an active area of research. This can be thought of as a sub-domain of micro and bio-robotics fields. If capsule and micro-robot localization problem in human body is solved, then it may potentially lead to less invasive treatments for G.I. diseases and other micro-robot assisted medical procedures. Several approaches have been investigated by the researchers to estimate capsule location. The proposed solutions are mainly static and thus prone to the changes in the propagation medium. We propose an adaptive algorithm based on expectation maximization technique for capsule localization. The proposed algorithm adaptively updates the estimated location based on the received radio frequency (RF) signal measurements.
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| 20. |
- Farooqui, Ashfaq Hussain, 1990, et al.
(author)
-
Synthesis of Supervisors for Unknown Plant Models Using Active Learning
- 2019
-
In: IEEE International Conference on Automation Science and Engineering. - 2161-8070 .- 2161-8089. ; August-2019, s. 502-508
-
Conference paper (peer-reviewed)abstract
- This paper proposes an approach to synthesize a discrete-event supervisor to control a plant, the behavior model of which is unknown, so as to satisfy a given specification. To this end, the $L^{*}$ algorithm is modified so that it can actively query a plant simulation and the specification to hypothesize a supervisor. The resulting hypothesis is the maximally permissive controllable supervisor from which the maximally permissive controllable and non-blocking supervisor can be extracted. The practicality of this method is demonstrated by an example.
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| 21. |
- Hagmar, Hannes, 1990, et al.
(author)
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Deep Reinforcement Learning for Long-Term Voltage Stability Control
- 2022
-
In: 11th Bulk Power Systems Dynamics and Control Symposium (IREP 2022).
-
Conference paper (peer-reviewed)abstract
- Deep reinforcement learning (DRL) is a machine learning-based method suited for complex and high-dimensional control problems. In this study, a real-time control system based on DRL is developed for long-term voltage stability events. The possibility of using system services from demand response (DR) and energy storage systems (ESS) as control measures to stabilize the system is investigated. The performance of the DRL control is evaluated on a modified Nordic32 test system. The results show that the DRL control quickly learns an effective control policy that can handle the uncertainty involved when using DR and ESS. The DRL control is compared to a rule-based load shedding scheme and the DRL control is shown to stabilize the system both significantly faster and with lesser load curtailment. Finally, when testing and evaluating the performance on load and disturbance scenarios that were not included in the training data, the robustness and generalization capability of the control were shown to be effective.
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| 22. |
- Itävuo, Pekka, et al.
(author)
-
Mass balance control of crushing circuits
- 2019
-
In: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 135, s. 37-47
-
Journal article (peer-reviewed)abstract
- This paper describes a novel circuit-wide control scheme that addresses the challenging problem of mass balance control of crushing circuits. The control objective is to ensure 100% utilization at the circuit bottleneck and hence push the realized performance towards the theoretical maximum. The present control problem is challenging due to long transport delays, complex circuit layout, under-actuated process, several uncontrolled disturbance flows, varying number of active equipment, varying downstream demand, and changing bottleneck location. The proposed mass balance control scheme involves feeding the circuit according to actual demand and realized circuit throughput, whilst maintaining the amount of material accumulated into the circuit and ensuring the physical integrity of the circuit. Therefore, the circuit feeding is based on the realized processing capacity, rather than an individual bin level or an operator decision. To ensure the efficient use of available surge capacity, a limiting control structure is proposed to simultaneously realize the in-circuit multi-objective limit violation control and loose bin level control strategy. The proposed scheme offers a simple solution for the otherwise complex control problem, which can be easily and efficiently implemented using classic control methods. The paper details an entire design procedure, from the fundamental theory, through dynamic modeling and controller tuning, to the complete circuit control system design and implementation. The proposed scheme is evaluated under extensive full-scale and simulated experiments at various production scenarios and equipment combinations. The rigorous control experiments revealed that the proposed scheme delivered the desired behavior in every possible scenario. This enables the circuit to reach its true potential.
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| 23. |
- Larsson, L. Viktor
(author)
-
Control Aspects of Complex Hydromechanical Transmissions : with a Focus on Displacement Control
- 2017
-
Licentiate thesis (other academic/artistic)abstract
- This thesis deals with control aspects of complex hydromechanical transmissions. The overall purpose is to increase the knowledge of important aspects to consider during the development of hydromechanical transmissions to ensure transmission functionality. These include ways of evaluating control strategies in early design stages as well as dynamic properties and control aspects of displacement controllers, which are key components in these systems.Fuel prices and environmental concerns are factors that drive research on propulsion in heavy construction machinery. Hydromechanical transmissions are strong competitors to conventional torque-converter transmissions used in this application today. They offer high efficiency and wide speed/torque conversion ranges, and may easily be converted to hybrids that allow further fuel savings through energy recuperation. One challenge with hydromechanical transmissions is that they offer many different configurations, which in turn makes it important to enable evaluation of control aspects in early design stages. In this thesis, hardware-in-the-loop simulations, which blend hardware tests and standard software-based simulations, are considered to be a suitable method. A multiple-mode transmission applied to a mid-sized construction machine is modelled and evaluated in offline simulations as well as in hardware-in-the-loopsimulations.Hydromechanical transmissions rely on efficient variable pumps/motors with fast, accurate displacement controllers. This thesis studies the dynamic behaviour of the displacement controller in swash-plate axial-piston pumps/motors. A novel control approach in which the displacement is measured with an external sensor is proposed. Performance and limitations of the approach are tested in simulations and in experiments. The experiments showed a significantly improved performance with a controller that is slightly more advanced than a standard proportional controller. The implementation of the controller allows simple tuning and good predictability of the displacement response.
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| 24. |
- Mahmoud, Sara, 1988-, et al.
(author)
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Where to from here? : On the future development of autonomous vehicles from a cognitive systems perspective
- 2022
-
In: Cognitive Systems Research. - : Elsevier. - 2214-4366 .- 1389-0417. ; 76, s. 63-77
-
Journal article (peer-reviewed)abstract
- Self-driving cars not only solve the problem of navigating safely from location A to location B; they also have to deal with an abundance of (sometimes unpredictable) factors, such as traffic rules, weather conditions, and interactions with humans. Over the last decades, different approaches have been proposed to design intelligent driving systems for self-driving cars that can deal with an uncontrolled environment. Some of them are derived from computationalist paradigms, formulating mathematical models that define the driving agent, while other approaches take inspiration from biological cognition. However, despite the extensive work in the field of self-driving cars, many open questions remain. Here, we discuss the different approaches for implementing driving systems for self-driving cars, as well as the computational paradigms from which they originate. In doing so, we highlight two key messages: First, further progress in the field might depend on adapting new paradigms as opposed to pushing technical innovations in those currently used. Specifically, we discuss how paradigms from cognitive systems research can be a source of inspiration for further development in modeling driving systems, highlighting emergent approaches as a possible starting point. Second, self-driving cars can themselves be considered cognitive systems in a meaningful sense, and are therefore a relevant, yet underutilised resource in the study of cognitive mechanisms. Overall, we argue for a stronger synergy between the fields of cognitive systems and self-driving vehicles.
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| 25. |
- Mendoza Trejo, Omar
(author)
-
Robust Concurrent Design of a 2-DOF Collaborative Robot (Cobot)
- 2021
-
In: IEEE/ASME Transactions on Mechatronics. - 1083-4435. ; 26, s. 347-357
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Journal article (peer-reviewed)abstract
- Uncertainties play a fundamental role in systems design, since the device behavior may be undesirable in the presence of unknown parameters. For devices interacting with humans, the force exerted by different operators represents a source of uncertainty, which under specific circumstances, could lead to undesired performance. This article proposes a robust concurrent design of a planar 2-DOF cobot modeled as a differential algebraic system and considers the force exerted by the human operator as the output of a PD controller. The robust concurrent design keeps the system performance as less sensitive as possible despite the different operators that interact with the device. Therefore, we establish the robust concurrent design as a multiobjective dynamic optimization problem, intended to minimize both the trajectory tracking error and its sensitivity with respect to uncertain parameters. The source of uncertainty comes from the force applied by the human operator while the independent variables are the inertial and kinematic parameters of the links in the kinematic chain, as well as the cobot controller gains. Experimental results show the effectiveness of the proposed design methodology.
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