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Comparative study of the static and quasi-static compliance measurement procedures on industrial manipulatorsKersch, Katrin, Rana, Anwar Ahmad January 2021 (has links)
Serial articulated industrial manipulators are increasingly used in machining applications due to their flexibility in application and their cost-effectiveness compared to conventional machinery. However, the use of industrial manipulators in machining processes that subject the robot to high loads such as in drilling is limited. The relatively low mechanical stiffness leads to position offsets from the anticipated position. Efforts have been made in the past to create manipulator calibration methods to compensate for their low stiffness and to increase their pose accuracy. The Department of Production Engineering at KTH Royal Institute of Technology defined a static and quasi-static compliance calibration procedure for industrial manipulators. Contrary to the hypothesis, the two methods produce different results in terms of the measured magnitude of Cartesian deflections. This study compares static and quasi-static compliance measurement procedures on an ABB IRB 6700-300/2.70 and aims at finding causes for the difference in the measured deflection of the manipulator between the two methods. Therefore, a literature review is performed and based on the review a novel quasi-static measurement procedure is presented. Deflections during the application of static and quasi-static loads with a frequency of less than 0.5 Hz on the manipulator are measured and compared. Differences in deflection are seen and potential causes are analyzed in several experiments. Namely, by changing parameters the resulting effects on the manipulator due to kinematic errors and dynamic effects are investigated. The results stress that unlike the expectation based on the theory of mechanics the system shows a dynamic behavior if a periodic loading with a frequency of less than 0.5Hz is applied during the quasi-static experiments. The difference in deflection is thus explained through load dissipation by damping and inertial forces during the quasi-static measurements of the novel method. This does not apply to the quasi-static measurement procedure defined by the Production Engineering department. Moreover, differences in deflection were identified due to friction and backlash acting in the transmissions system of the motors when static loads are applied in certain regions of the task space. Future work in the analysis of differences in compliance measurement procedures is encouraged to find causes for the quasi-static measurement results of the department. / Serieartikulerade industriella manipulatorer används allt mer i bearbetande operationer tack vare dess flexibilitet i användande och dess kostnadseffektivitet jämfört med konventionella maskiner. Dock är användandet av industriella manipulatorer i bearbetningsprocesser som utsätter roboten för höga laster så som borrande begränsat. Den relativt höga mekaniska stelheten leder till positionsförskjutningar från den förväntade positionen. Ansträngningar har tidigare gjorts för att skapa kalibreringsmetoder för manipulatorer som ska kompensera för dess låga stelhet och öka dess position och orienterings-exakthet. Institutionen för industriell produktion vid Kungliga Tekniska Högskolan har definerat en statisk och kvasistatisk efterlevnads-kalibrerings-procedur för industriella manipulatorer. I motsats till hypotesen producerade de två metoderna olika resultat i avseende till den uppmätta magnituden för Kartesiska böjningar. Denna studie jämför statiska och kvasistatiska efterlevnads-mätnings-procedurer hos en ABB IRB 6700-300/2.70 och siktar på att hitta orsaker för skillnaden i den uppmätta böjningen av manipulatorn mellan de två metoderna. Därmed genomförs en litteraturstudie och baserat på en översikt presenteras en ny kvasistatisk mätningsprocedur. Böjningar under påverkan av statiska och kvasistatiska laster på under 0.5 Hz på manipulatorn uppmäts och jämförs. Skillnader i böjningar kan ses och potentiella orsaker analyseras i flera experiment. Genom byte av parametrar kan effekter på den industriella manipulatorn som orsakas av kinematiska fel och dynamiska effekter undersökas. Resultatet understryker att olikt förväntningarna som baserats på teorier från mekaniken uppvisar systemet ett dymaniskt beteende om en periodisk last på mindre än 0.5 Hz appliceras under de kvasistatiska experimenten. Skillnaden i böjningen förklaras därmed genom ett lastminskande som beror på dämpande och tröga krafter under de kvasistatiska mätningarna av den nya metoden. Detta gäller inte den kvasistatiska mätningsproceduren som definerats av Institutionen för industriell produktion. Utöver detta identifieras skillnader i böjningar med avseende på friktion och glapp i överföringssystemet i motorerna när statiska laster appliceras på specifika regioner i arbetsområdet. Framtida arbete i analys av skillnader i efterlevnadsmätnings-procedurerna uppmuntras för att hitta orsaker till institutionens kvasistatiska mätningsresultat.
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Asynchronous Event-Feature Detection and Tracking for SLAM InitializationTa, Tai January 2024 (has links)
Traditional cameras are most commonly used in visual SLAM to provide visual information about the scene and positional information about the camera motion. However, in the presence of varying illumination and rapid camera movement, the visual quality captured by traditional cameras diminishes. This limits the applicability of visual SLAM in challenging environments such as search and rescue situations. The emerging event camera has been shown to overcome the limitations of the traditional camera with the event camera's superior temporal resolution and wider dynamic range, opening up new areas of applications and research for event-based SLAM. In this thesis, several asynchronous feature detectors and trackers will be used to initialize SLAM using event camera data. To assess the pose estimation accuracy between the different feature detectors and trackers, the initialization performance was evaluated from datasets captured from various environments. Furthermore, two different methods to align corner-events were evaluated on the datasets to assess the difference. Results show that besides some slight variation in the number of accepted initializations, the alignment methods show no overall difference in any metric. Overall highest performance among the event-based trackers for initialization is HASTE with mostly high pose accuracy and a high number of accepted initializations. However, the performance degrades in featureless scenes. CET on the other hand shows mostly lower performance compared to HASTE.
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