Feature Based Modeling and Mapping of Tree Trunks and Natural Terrain Using 3D Laser Scanner Measurement System

This paper presents a novel approach to measure tree trunks and to model the ground using a 3D laser scanner. The 3D scanner, self-build using two 2D Sick scanners on a rotating base, measures each scan line approximately at 45° angle towards the ground and the trees. Single scan lines are segmented to find ground and tree returns. 3D point clouds from the surrounding forest are recorded while the measuring vehicle is moving. Sequential scan lines are joined together as the pose changes are reduced from the older buffered measurements. Laser odometry and inertial measurements are used to measure the pose changes. The ground is modeled by fitting a 1m grid to 3D point cloud extracted using a ground return detector. Tree trunks are searched from the 3D point cloud using a histogram approach to segment measurements into separate point clouds for each tree trunk. Tree trunks are modeled using ten circle features one on the other using the extracted point cloud. Instead of using the whole point cloud, mapping is done only for the extracted features and the travelled path to save computation time. Our method can detect nearly all tree trunks and measure them on short ranges of less than 8m with errors less than 4cm in diameter.Peer reviewe

Current state of digital signal processing in myoelectric interfaces and related applications

This review discusses the critical issues and recommended practices from the perspective of myoelectric interfaces. The major benefits and challenges of myoelectric interfaces are evaluated. The article aims to fill gaps left by previous reviews and identify avenues for future research. Recommendations are given, for example, for electrode placement, sampling rate, segmentation, and classifiers. Four groups of applications where myoelectric interfaces have been adopted are identified: assistive technology, rehabilitation technology, input devices, and silent speech interfaces. The state-of-the-art applications in each of these groups are presented.Peer reviewe

Sway Estimation Using Inertial Measurement Units for Cranes with a Rotating Tool

Cranes have often a freely hanging load or tool that starts easily swaying. Anti-sway control requires that the angles and angular velocities of the swinging object are measured. Some cranes can also rotate the tool with a hydraulic motor, and in many cases this rotator angle should also be known. Instrumenting all three axes, two swaying and one rotating axis, with traditional rotary encoders can be challenging. We propose an extended Kalman filter based system using two inertial measurement units. This system can measure the swaying in both directions and estimate the rotator angle. Computer vision system is used as reference. The initial results show that the error is approximately 5 degrees in the rotator angle and 2 degrees in the sway angles. The observer runs at 100 Hz on an embedded microcontroller.Peer reviewe

Real-time Detection of Young Spruce Using Color and Texture Features on an Autonomous Forest Machine

Forest machines are manually operated machines that are efficient when operated by a professional. Point cleaning is a silvicultural task in which weeds are removed around a young spruce tree. To automate point cleaning, machine vision methods are used for identifying spruce trees. A texture analysis method based on the Radon and wavelet transforms is implemented for the task. Real-time GPU implementation of algorithms is programmed using CUDA framework. Compared to a single thread CPU implementation, our GPU implementation is between 18 to 80 times faster depending on the size of image blocks used. Color information is used in addition of texture and a location estimate of the tree is extracted from the detection result. The developed spruce detection system is used as a part of an autonomous point cleaning machine. To control the system, an integrated user interface is presented. It allows the operator to control, monitor and train the system online.Peer reviewe

Augmented Reality in Forest Machine Cabin

Augmented reality human machine interface is demonstrated in the cabin of a forest machine outdoors for the first time in real time. In this work, we propose a system setup and a real-time capable algorithm to augment the operator’s visual field with measurements from the forest machine and its environment. In the demonstration, an instrumented forestry crane and a lidar are used to model the pose of the crane and its surroundings. In our approach, a camera and an inertial measurement unit are used to estimate the pose of the operator’s head in difficult lighting conditions with the help of planar markers placed on the cabin structures. Using the estimate, a point cloud and a crane model are superimposed on the video feed to form an augmented reality view. Our system is tested to work outdoors using a forest machine research platform in real time with encouraging initial results.Peer reviewe

Detection and species classification of young trees using machine perception for a semi-autonomous forest machine

An approach to automatically detect and classify young spruce and birch trees in forest environment is presented. The method could be used in autonomous or semi-autonomous forest machines during tending operations. Detection is done by segmenting laser range images formed by a rotating laser scanner. Classification is done with a two-class Naive Bayes classifier based on image texture features. Multiple combinations of 99 features were tested and the best classifier included eight features from the co-occurrence matrix, local binary patterns, statistical geometrical features and Gabor filter. 79% of spruces and birches in the testing material were detected and 74% of these were correctly classified. Results suggest that the approach is suitable but there are still some challenges in each of the processing steps. Iteration between segmentation and classification is needed to increase reliability.Peer reviewe

ISO 11783 Compliant Forest Crane As a Platform for Automatic Control

ISO 11783 is a communication standard for agricultural and forest machines. This standard allows an implement to command specific functions of a tractor. Agricultural tractors can be equipped for silvicultural work forming small scale forest machine. It could cost-efficiently compete against common forest machines in some tasks. We have developed an ISO 11783 compliant forest crane connected to an agricultural tractor. The combination is designed to work as a test platform for an autonomous forest machine. The dynamics of the system have been studied using first and second-order models. Based on identification tests with no load on the crane, first-order model is sufficient for describing the motion of most of the cylinders. According to the identification results, small controls do not cause motion on the crane, and a non-linear model is required. Currently used hydraulics of agricultural tractors is not entirely adequate for controlling forest cranes. With more intelligent tractor hydraulics, the crane could be more controllable and energy-efficient.Peer reviewe

Perusteita seuraavan sukupolven metsävarajärjestelmälle – Forest Big Data -hanke

Tieteen tori: Yksityiskohtainen metsävaratiet

IOT as a tool to reveal the causative agents of indoor air related adverse effects : Problems connected to quality of indoor air are frequent and cause remarkable damages to health and monetary losses

Tulokset tuotettiin Aaltoyliopiston Sähkötekniikan- ja Automaation laitoksen (EEA) "Sisäilmapoliisi" tutkimushankkeessa 2017-2018Uusien sisäilman tutkimus- ja mittausmenetelmien avulla voidaan havainnoida sisäilmassa aineita ennenkuin ne ehtivät aiheuttaa ongelmia tilojen käyttäjille. Vesihöyry kuljettaa ongelma-aineita rakenteista ilmaan varsinkin jos tila on alipaineinen ulkoilmaan tai viereisiin tiloihin verrattuna.Perinteisesti on ajateltu että ihmiset altistuvat haihtuville aineille ja pienhiukkasille, jotka voivat myös toimia haitta-aineiden kuljettajina Sisäilmapoliisi hankkeen tutkimukset osoittavat että haihtumattiomat aineet voivat kulkeutua sisäilmaan myös vesihöyryn kuljettamina. Esineiden internet, IoT, mahdollistaa reaaliaikaisen mittausten seurannan ja analyysin ja vähentää sisäilmaston mittausten kustannuksia

Observation and elimination of indoor air impurities using aqueous aerosols

Presented at Indoor Air Seminar (Helsinki, Finland) 15 March, 2018. ISBN 978-952-5236-46-0.Mittasimme aineiden (hometoksiinit; rakennus- ja saneeraustuotteiden kemikaalit, siivousaineet) kulkeutumista päästölähteistä ilmaan tutkimuskammioissa. Tutkittavat aineet annosteltiin kammioiden pohjalla oleviin avoimiin astioihin. Kammioiden ilman kosteutta säädettiin lisäämällä pohjalle vettä ja ilmankostutin- ja kuivainlaitteilla. Lämpötilaa, kosteutta ja TVOC-pitoisuutta monitoroitiin jatkuvatoimisilla antureilla. Kammioilman vesihöyry ja vesiaerosolit tiivistettiin nestemäiseksi vedeksi kuivaimen säiliöön. Kun tiivistevesi analysoitiin, havaittiin, että mikrobitoksiinit (okratoksiini A, enniatiini B) ja siivous- ja saneeraustuotteiden sisältämät antimikrobiset (PHMG) aineet, neutraalit (polyglykoli-alkoksyylit) ja kationiset tensidit (DDDMAC) siirtyivät pinnoilta ilmaan ja sieltä ilmankuivaimen kondenssivesisäiliöön.We measured mobility of nonvolatile fungal toxins and chemical substances in products used in building construction or maintenance into indoor air. The measurement was conducted in enclosed chambers provided with sensors for continuous monitoring of air humidity, temperature, organic substance (TVOC). Airborn humidicity was cyclically up/down adjusted using humidifier / dehumidifier. Substances tested for emission, were placed in open dishes on chamber floor. Airborn humidity was condensed into liquid water, harvested in dehumidifer storage container, and analysed at the end of each experiment.We found that nonvolatile substances such as fungal toxins (ochratoxin A), non-ionic and cationic tensides (polyoxyethylene alkanol ethers, didecyldimethyl ammonium chloride) and antimicrobial biocidal substances (PHMG) , contained in cleaning and sanitation products in buildings, translocated were recovered in the the dehumidifer condensate, thus indicating airborn migration.Peer reviewe