| 1. |
- Mohamed, S. A. S., et al.
(författare)
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Asynchronous Corner Tracking Algorithm Based on Lifetime of Events for DAVIS Cameras
- 2020
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Ingår i: 15th International Symposium on Visual Computing, ISVC 2020. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 530-541
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Konferensbidrag (refereegranskat)abstract
- Event cameras, i.e., the Dynamic and Active-pixel Vision Sensor (DAVIS) ones, capture the intensity changes in the scene and generates a stream of events in an asynchronous fashion. The output rate of such cameras can reach up to 10 million events per second in high dynamic environments. DAVIS cameras use novel vision sensors that mimic human eyes. Their attractive attributes, such as high output rate, High Dynamic Range (HDR), and high pixel bandwidth, make them an ideal solution for applications that require high-frequency tracking. Moreover, applications that operate in challenging lighting scenarios can exploit from the high HDR of event cameras, i.e., 140 dB compared to 60 dB of traditional cameras. In this paper, a novel asynchronous corner tracking method is proposed that uses both events and intensity images captured by a DAVIS camera. The Harris algorithm is used to extract features, i.e., frame-corners from keyframes, i.e., intensity images. Afterward, a matching algorithm is used to extract event-corners from the stream of events. Events are solely used to perform asynchronous tracking until the next keyframe is captured. Neighboring events, within a window size of 5 × 5 pixels around the event-corner, are used to calculate the velocity and direction of extracted event-corners by fitting the 2D planar using a randomized Hough transform algorithm. Experimental evaluation showed that our approach is able to update the location of the extracted corners up to 100 times during the blind time of traditional cameras, i.e., between two consecutive intensity images.
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| 2. |
- Mohamed, S. A. S., et al.
(författare)
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DBA-Filter : A Dynamic Background Activity Noise Filtering Algorithm for Event Cameras
- 2022
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Ingår i: Proceedings of the 2021 Computing Conference, Volume 1. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 685-696
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Konferensbidrag (refereegranskat)abstract
- Newly emerged dynamic vision sensors (DVS) offer a great potential over traditional sensors (e.g. CMOS) since they have a high temporal resolution in the order of μs, ultra-low power consumption and high dynamic range up to 140 dB compared to 60 dB in frame cameras. Unlike traditional cameras, the output of DVS cameras is a stream of events that encodes the location of the pixel, time, and polarity of the brightness change. An event is triggered when the change of brightness, i.e. log intensity, of a pixel exceeds a certain threshold. The output of event cameras often contains a significant amount of noise (outlier events) alongside the signal (inlier events). The main cause of that is transistor switch leakage and noise. This paper presents a dynamic background activity filtering, called DBA-filter, for event cameras based on an adaptation of the K-nearest neighbor (KNN) algorithm and the optical flow. Results show that the proposed algorithm is able to achieve a high signal to noise ratio up to 13.64 dB.
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| 3. |
- Mohamed, S. A. S., et al.
(författare)
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Dynamic resource-aware corner detection for bio-inspired vision sensors
- 2020
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Ingår i: 2020 25th International Conference on Pattern Recognition, (ICPR). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 10465-10472
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Konferensbidrag (refereegranskat)abstract
- Event-based cameras are vision devices that transmit only brightness changes with low latency and ultra-low power consumption. Such characteristics make event-based cameras attractive in the field of localization and object tracking in resource-constrained systems. Since the number of generated events in such cameras is huge, the selection and filtering of the incoming events are beneficial from both increasing the accuracy of the features and reducing the computational load. In this paper, we present an algorithm to detect asynchronous corners form a stream of events in real-time on embedded systems. The algorithm is called the Three Layer Filtering-Harris or TLF-Harris algorithm. The algorithm is based on an events' filtering strategy whose purpose is 1) to increase the accuracy by deliberately eliminating some incoming events, i.e., noise and 2) to improve the real-time performance of the system, i.e., preserving a constant throughput in terms of input events per second, by discarding unnecessary events with a limited accuracy loss. An approximation of the Harris algorithm, in turn, is used to exploit its high-quality detection capability with a low-complexity implementation to enable seamless real-time performance on embedded computing platforms. The proposed algorithm is capable of selecting the best corner candidate among neighbors and achieves an average execution time savings of 59% compared with the conventional Harris score. Moreover, our approach outperforms the competing methods, such as eFAST, eHarris, and FA-Harris, in terms of real-time performance, and surpasses Arc* in terms of accuracy.
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| 4. |
- Yasin, J. N., et al.
(författare)
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Dynamic Formation Reshaping Based on Point Set Registration in a Swarm of Drones
- 2021
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Ingår i: Advances in Intelligent Systems and Computing. - Cham : Springer Nature. ; , s. 577-588
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Konferensbidrag (refereegranskat)abstract
- This work focuses on the formation reshaping in an optimized manner in autonomous swarm of drones. Here, the two main problems are: 1) how to break and reshape the initial formation in an optimal manner, and 2) how to do such reformation while minimizing the overall deviation of the drones and the overall time, i.e. without slowing down. To address the first problem, we introduce a set of routines for the drones/agents to follow while reshaping to a secondary formation shape. And the second problem is resolved by utilizing the temperature function reduction technique, originally used in the point set registration process. The goal is to be able to dynamically reform the shape of multi-agent based swarm in near-optimal manner while going through narrow openings between, for instance obstacles, and then bringing the agents back to their original shape after passing through the narrow passage using point set registration technique.
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| 5. |
- Yasin, J. N., et al.
(författare)
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Low-cost ultrasonic based object detection and collision avoidance method for autonomous robots
- 2021
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Ingår i: International Journal of Information Technology (Singapore). - : Springer Nature. - 2511-2104 .- 2511-2112. ; 13:1, s. 97-107
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Tidskriftsartikel (refereegranskat)abstract
- This work focuses on the development of an effective collision avoidance algorithm that detects and avoids obstacles autonomously in the vicinity of a potential collision by using a single ultrasonic sensor and controlling the movement of the vehicle. The objectives are to minimise the deviation from the vehicle’s original path and also the development of an algorithm utilising one of the cheapest sensors available for very lost cost systems. For instance, in a scenario where the main ranging sensor malfunctions, a backup low cost sensor is required for safe navigation of the vehicle while keeping the deviation to a minimum. The developed algorithm utilises only one ultrasonic sensor and approximates the front shape of the detected object by sweeping the sensor mounted on top of the unmanned vehicle. In this proposed approach, the sensor is rotated for shape approximation and edge detection instead of moving the robot around the encountered obstacle. It has been tested in various indoor situations using different shapes of objects, stationary objects, moving objects, and soft or irregularly shaped objects. The results show that the algorithm provides satisfactory outcomes by entirely avoiding obstacles and rerouting the vehicle with a minimal deviation.
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| 6. |
- Yasin, J N, et al.
(författare)
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Navigation of Autonomous Swarm of Drones Using Translational Coordinates
- 2020
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Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer. ; , s. 353-362
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work focuses on an autonomous swarm of drones, a multi-agent system, where the leader agent has the capability of intelligent decision making while the other agents in the swarm follow the leader blindly. The proposed algorithm helps with cost cutting especially in the multi-drone systems, i.e., swarms, by reducing the power consumption and processing requirements of each individual agent. It is shown that by applying a pre-specified formation design with feedback cross-referencing between the agents, the swarm as a whole can not only maintain the desired formation and navigate but also avoid collisions with obstacles and other drones. Furthermore, the power consumed by the nodes in the considered test scenario, is reduced by 50% by utilising the proposed methodology.
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| 7. |
- Guang, L., et al.
(författare)
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Coarse and fine-grained monitoring and reconfiguration for energy-efficient NoCs
- 2012
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Ingår i: System on Chip (SoC), 2012 International Symposium on. - : IEEE. - 9781467328951 ; , s. 6376351-
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Konferensbidrag (refereegranskat)abstract
- Comparative evaluations of centralized, clustered and distributed architectures, for energy management in NoCs, are presented. The paper starts with the systematic examination of the monitoring, decision-making, and reconfiguration processes in building coarse and fine-grained self-adaptation architectures. With examining the physical support in modern technology, network-wide, cluster-wide and per-node energy-management architectures on NoCs are presented, utilizing either voltage regulators or multiple on-chip power delivery networks (MPNs). To identify the effectiveness and efficiency of energy-performance tradeoffs, extensive quantitative simulations are performed with various temporal and spatially changing traffics. Based on the results, we can first observe that the centralized architecture can not adapt to the traffic's spatial locality for effective energy-performance tradeoff. Second, the distributed energy management has the lowest energy-delay product mostly attributed to the fast voltage switching of MPNs, while the synchronization incurs noticeable energy overhead. The clustered architecture, last but not least, is a suitable alternative when the advanced MPN technology is not available. It has low energy and energy-delay product, with very small energy overhead from the monitoring communication.
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| 8. |
- Guang, L., et al.
(författare)
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HLS-DoNoC : High-level simulator for dynamically organizational NoCs
- 2012
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Ingår i: Design and Diagnostics of Electronic Circuits & Systems (DDECS), 2012 IEEE 15th International Symposium on. - : IEEE. - 9781467311854 ; , s. 89-94
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Konferensbidrag (refereegranskat)abstract
- A high-level simulator is presented for the design and analysis of dynamically organizational Networks-on-Chip (DoNoCs). The DoNoC is able to organize statically or dynamically different network nodes for run-time coarse and fine grained reconfiguration, in particular power management. As an important step in the design flow, a simulator for early-stage design exploration is the focus of the paper. Built upon classic wormhole-based NoC architecture, the simulator is capable of experimenting diverse run-time monitoring and reconfiguration methods. In particular, dynamic clusterization can be performed with inter-cluster interfaces properly configured at the run-time. The simulator is flit-level accurate, trace-driven, and easy-to-reconfigure. It supports both synchronous and ratiochronous timing, and can provide the communication performance and power/energy consumption. The paper demonstrates the usage of the simulator in the design of various cluster-based power management schemes.
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| 9. |
- Guang, L., et al.
(författare)
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Survey of self-adaptive NoCs with energy-efficiency and dependability
- 2012
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Ingår i: International Journal of Embedded and Real-Time Communication Systems. - : IGI Global. - 1947-3176 .- 1947-3184. ; 3:2, s. 1-22
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Forskningsöversikt (refereegranskat)abstract
- The self-adaptive Network-on-Chip (NoC) is a promising communication architecture for massively parallel embedded systems. With constant technology scaling and the consequent stronger influence of process variations, the necessity of run-time monitoring and adaptive reconfiguration becomes widely acknowledged. This article presents a survey of existing techniques and methods, in particular for energy efficiency and dependability. The article firstly examines the motivation of self-adaptive computing in parallel embedded systems. A self-adaptive system model is abstracted, which is composed of goals, monitoring interface, and self-adaptation. Based on the model, the authors extensively survey previous works addressing adaptive NoCs with different monitoring techniques and reconfiguration methods, for power/energy optimization and dependability enhancement. Several design examples are elaborated which serve proper guiding purposes. The authors also identify important issues which are often overlooked or deserve more attention. The article provides review and insight for future design on this topic.
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| 10. |
- Jafri, Syed, et al.
(författare)
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Implementation and evaluation of configuration scrubbing on CGRAs : A case study
- 2013
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Ingår i: 2013 International Symposium on System-on-Chip, SoC 2013 - Proceedings. - : IEEE Computer Society. ; , s. 6675262-
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the overhead imposed by various configuration scrubbing techniques used in fault-tolerant Coarse Grained Reconfigurable Arrays (CGRAs). Today, reconfigurable architectures host large configuration memories. As we progress further in the nanometer regime, these configuration memories have become increasingly susceptible to single event upsets caused e.g. by cosmic radiation. Configuration scrubbing is a frequently used technique to protect these configuration memories against single event upsets. Existing works on configuration scrubbing deal only with FPGA without any reference to the CGRAs (in which configuration memories consume up to 50% of silicon area). Moreover, in the known literature lacks a comprehensive comparison of various configuration scrubbing techniques to guide system designers about the merits/demerits of different scrubbing methods which could be applied to CGRAs. To address these problems, in this paper we classify various configuration scrubbing techniques and quantify their trade-offs when implemented on a CGRA. Synthesis results reveal that scrubbing logic incurs negligible silicon overhead (up to 3% of the area of computational units). Simulation results obtained for a few algorithms/applications (FFT, FIR, matrix multiplication, and WLAN) show that the choice of the configuration scrubbing scheme (external vs. internal) has significant impact on both the size of configuration memory and the number of reconfiguration cycles (respectively 20-80% more and up to 38 times more for the former).
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