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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Využití traktorů s pásovým podvozkem v podniku zemědělské prvovýroby

ROUČKA, František January 2018 (has links)
The diploma thesis, which deals with the usage of tractors with tracked chassis in the agricultural primary production, presents in a literature overview the design of the chassis of wheeled tractors, which is supplemented with front axle suspension systems. Main theoretical part of the overview describes the construction of the tracked chassis. There are mentioned and described all units of significant producers of tracked tractors. Further, the work describes the design of suspension of tracked tractors and the possibility of control of the tracked chassis. The theoretical part ends with a chapter focusing on semi-tracked tractors. Practical part shows the methodology and results of the measuring by use of the tracked tractors in the agricultural company annual production, focused on the utilization of each Tractor-set. Thesis is completed by characteristic of the general agriculture company with the analysis of the investments and costs.
12

An Automated Ultrasound Calibration Framework Incorporating Elevation Beamwidth for Tracked Ultrasound Interventions

Chen, Kuiran 22 October 2012 (has links)
Image-guided surgeries employ advanced imaging and computing technologies to assist the surgeon when direct visualization is inadequate or unavailable. As modern surgeries continue to move toward minimally invasive procedures, tracked ultrasound (US), an emerging technology that uniquely combines US imaging and position tracking, has been increasingly used for intraoperative guidance in surgical interventions. The intrinsic accuracy of a tracked US system is primarily determined by a unique procedure called ``probe calibration", where a spatial registration between the coordinate systems of the transducer (provided by a tracking device affixed to the probe) and the US image plane must be established prior to imaging. Inaccurate system calibration causes misalignments between the US image and the surgical end-effectors, which may directly contribute to treatment failure. The probe calibration quality is further reduced by the "elevation beamwidth" or "slice thickness", a unique feature of the ultrasound beam pattern that gives rise to localization errors and imaging uncertainties. In this thesis, we aim to provide an automated, pure-computation-based, intraoperative calibration solution that also incorporates the slice thickness to improve the calibration accuracy, precision and reliability. The following contributions have been made during the course of this research. First, we have designed and developed an automated, freehand US calibration system with instant feedback on its calibration accuracy. The system was able to consistently achieve submillimeter accuracy with real-time performance. Furthermore, we have developed a novel beamwidth-weighted calibration framework (USB-FW) that incorporates US slice thickness to improve the estimation of calibration parameters. The new framework provides an effective means of quality control for calibration results. Extensive phantom validation demonstrated that USB-FW introduces statistically significant reduction (p = 0.001) in the calibration errors and produces calibration outcomes that are less variable than a conventional, non-beamwidth-weighted calibration. Finally, we were the first to introduce an automated, intraoperative Transrectal Ultrasound (TRUS) calibration technology for needle guidance in prostate brachytherapy. Our tests with multiple commercial TRUS scanners and brachytherapy stepper systems demonstrated that the proposed method is practical in use and can achieve high calibration accuracy, precision and robustness. / Thesis (Ph.D, Computing) -- Queen's University, 2012-10-22 16:18:55.439
13

Head tracked multi user autostereoscopic 3D display investigations

Brar, Rajwinder Singh January 2012 (has links)
The research covered in this thesis encompasses a consideration of 3D television requirements and a survey of stereoscopic and autostereoscopic methods. This confirms that although there is a lot of activity in this area, very little of this work could be considered suitable for television. The principle of operation, design of the components of the optical system and evaluation of two EU-funded (MUTED & HELIUM3D projects) glasses-free (autostereoscopic) displays is described. Four iterations of the display were built in MUTED, with the results of the first used in designing the second, third and fourth versions. The first three versions of the display use two-49 element arrays, one for the left eye and one for the right. A pattern of spots is projected onto the back of the arrays and these are converted into a series of collimated beams that form exit pupils after passing through the LCD. An exit pupil is a region in the viewing field where either a left or a right image is seen across the complete area of the screen; the positions of these are controlled by a multi-user head tracker. A laser projector was used in the first two versions and, although this projector operated on holographic principles in order to obtain the spot pattern required to produce the exit pupils, it should be noted that images seen by the viewers are not produced holographically so the overall display cannot be described as holographic. In the third version, the laser projector is replaced with a conventional LCOS projector to address the stability and brightness issues discovered in the second version. In 2009, true 120Hz displays became available; this led to the development of a fourth version of the MUTED display that uses 120Hz projector and LCD to overcome the problems of projector instability, produces full-resolution images and simplifies the display hardware. HELIUM3D: A multi-user autostereoscopic display based on laser scanning is also described in this thesis. This display also operates by providing head-tracked exit pupils. It incorporates a red, green and blue (RGB) laser illumination source that illuminates a light engine. Light directions are controlled by a spatial light modulator and are directed to the users’ eyes via a front screen assembly incorporating a novel Gabor superlens. In this work is described that covered the development of demonstrators that showed the principle of temporal multiplexing and a version of the final display that had limited functionality; the reason for this was the delivery of components required for a display with full functionality.
14

Metodologia para simulação dinâmica e otimização de veículos de esteira

Mezacasa, Nathan January 2018 (has links)
Devido as severas condições as quais veículos militares blindados de esteira são submetidos, o desenvolvimento de modelos que representam o comportamento dinâmico destes veículos torna-se imprescindível, para além da possibilidade de avaliação das intensidades das vibrações ocorrendo na cabine, ser possível criar veículos que tenham vantagens na mobilidade, fator esse que engloba tanto a transposição de obstáculos, como a rodagem em condições menos severas, e por fim, no tempo e na exatidão dos disparos, afetada pelas respostas dinâmicas que o veículo fornece. Para ser possível encontrar um veículo que desempenhe tais condições de forma satisfatória, apenas modelos que representem adequadamente as suas propriedades, apresentando respostas das acelerações e deslocamentos, não são suficientes. O objetivo deste trabalho é o desenvolvimento de um modelo numérico que tenha a capacidade de simular as condições dinâmicas extremas as quais um veículo de esteira é induzido, e também, otimizar o modelo, com a finalidade de encontrar molas e amortecedores capazes de proporcionar respostas adequadas às funções custo desenvolvidas. Estas funções objetivo são definidas como a combinação linear da aceleração e deslocamento, verticais e rotacionais, em conjunto de restrições impostas, objetivando encontrar uma combinação ideal para mobilidade, tempo e exatidão nos disparos e por fim, molas e amortecedores adequados as condições de logística Para proposta deste estudo, um modelo matemático 2D e um 3D, de um veículo de esteira, foi desenvolvido. O modelo possibilita a avaliação dos graus de liberdade de deslocamento vertical das massas não suspensas e do deslocamento vertical, arfagem e rolagem da massa suspensa. Os efeitos da esteira são modelados como molas verticais lineares exercendo uma força de restauração para alinhar as rodas de rodagem, proporcional ao deslocamento relativo entre essas rodas. A otimização é feita através de ferramentas numéricas presentes no software comercial Simulink, sendo necessário o desenvolvimento das funções custo que caracterizem os objetivos ideais para cada tipo de análise. Os resultados de simulações numéricas sob a forma de cursos de deslocamento de pontos característicos do casco e deslocamentos dos eixos de rodas em um sistema de coordenadas de referência assumido, também estão incluídos, bem como as quantidades de valor RMS de cada uma das respostas, comparando um veículo padrão, com o veículo com a suspensão otimizada. / Due to the severe conditions in which armored military vehicles are submitted, the development of models that represent the dynamic behavior of these vehicles becomes essential, besides the possibility of evaluating the vibration intensities occurring in the cabin, to be possible to create vehicles that have mobility a factor that encompasses both the transposition of obstacles, and the shooting in less severe conditions, and finally, in the time and accuracy of the shots, affected by the dynamic responses that the vehicle provides. In order to be able to find a vehicle that fulfills these conditions satisfactorily, only models that adequately represent its properties, presenting responses of the accelerations and displacements, are not enough. The objective of this work is the development of a numerical model that has the ability to simulate extreme dynamic conditions such as a tracked vehicle is induced, and also to optimize the model with the purpose of finding springs and shock absorbers capable of adequate alternative answers cost functions developed. These are the goals defined as a linear combination of acceleration and displacement, vertical and rotational, together imposed constraints, aiming to find an ideal combination for mobility, time and precision in the shots and, finally, springs and dampers suitable as logistics conditions To propose this study, a 2D and 3D mathematical model of a tracked vehicle were developed. The model allows the evaluation of the degrees of freedom of vertical displacement of the non-suspended masses and the vertical displacement, pitch and roll of the suspended mass. The effects of the track are modeled as linear vertical springs exerting a restoring force to align the road wheels, proportional to the relative displacement between these wheels. The optimization is done through numerical tools present in Simulink software, and it is necessary to develop cost functions that characterize the ideal objectives for each type of analysis. The results of numerical simulations in the form of displacement courses of characteristic hull points and wheel axle displacements in an assumed reference coordinate system are also included, as well as the RMS value quantities of each of the responses, comparing a standard vehicle with the optimized suspension.
15

Vehicle-terrain parameter estimation for small-scale robotic tracked vehicle

Dar, Tehmoor Mehmoud 02 August 2011 (has links)
Methods for estimating vehicle-terrain interaction parameters for small scale robotic vehicles have been formulated and evaluated using both simulation and experimental studies. A model basis was developed, guided by experimental studies with an iRobot PackBot. The intention was to demonstrate whether a nominally instrumented robotic vehicle could be used as a test platform for generating data for vehicle-terrain parameter estimation. A comprehensive skid-steered model was found to be sensitive enough to distinguish between various forms of unknown terrains. This simulation study also verified that the Bekker model for large scale vehicles adopted for this research was applicable to the small scale robotic vehicle used in this work. This fact was also confirmed by estimating coefficients of friction and establishing their dependence on forward velocity and turning radius as the vehicle traverses different terrains. On establishing that mobility measurements for this robotic were sufficiently sensitive, it was found that estimates could be made of key dynamic variables and vehicle-terrain interaction parameters. Four main contributions are described for reliably and robustly using PackBot data for vehicle-terrain property estimation. These estimation methods should contribute to efforts in improving mobility of small scale tracked vehicles on uncertain terrains. The approach is embodied in a multi-tiered algorithm based on the dynamic and kinematic models for skid-steering as well as tractive force models parameterized by key vehicle-terrain parameters. In order to estimate and characterize the key parameters, nonlinear estimation techniques such as the Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), and a General Newton Raphson (GNR) method are integrated into this multi-tiered algorithm. A unique idea in using an EKF with an added State Noise Compensation algorithm is presented which shows its robustness and consistency in estimating slip variables and other parameters for deformable terrains. In the multi-tiered algorithm, a kinematic model of the robotic vehicle is used to estimate slip variables and turning radius. These estimated variables are stored in a truth table and used in a skid-steered dynamic model to estimate the coefficients of friction. The total estimated slip on the left and right track, along with the total tractive force computed using a motor model, are then used in the GNR algorithm to estimate the key vehicle-terrain parameters. These estimated parameters are cross-checked and confirmed with EKF estimation results. Further, these simulation results verify that the tracked vehicle tractive force is not dependent on cohesion for frictional soils. This sequential algorithm is shown to be effective in estimating vehicle-terrain interaction properties with relatively good accuracy. The estimated results obtained from UKF and EKF are verified and compared with available experimental data, and tested on a PackBot traversing specified terrains at the Southwest Research Institute (SwRI), Small Robotics Testbed in San Antonio, Texas. In the end, based on the development and evaluation of small scale vehicle testing, the effectiveness of on-board sensing methods and estimation techniques are also discussed for potential use in real time estimation of vehicle-terrain parameters. / text
16

Elhybridteknik i bandvagnssystemet : Den militära nyttan i logistikfunktionen / Hybrid electric technology in tracked vehicles : Effects on military logistics

Andersson, Tobias January 2014 (has links)
Fossila bränslen är ändliga resurser och FMV menar i sin Tekniska Prognos 2013 att Försvarsmakten redan nu bör planera för en omställning till alternativa tekniker till dagens förbränningsmotor. Den teknik som verkar mest lämplig som interimslösning mellan framtidens vision om ren eldrift och förbränningsmotorn är elhybridteknik. Uppsatsen undersöker hur Försvarsmaktens logistikfunktion påverkas om bandvagnssystemet skulle övergå till seriehybridteknik. Uppsatsens ansats är kvalitativ med en kombination av textstudier, intervjuer samt ett frågeformulär som besvaras av totalt tre personer fördelat på Amf1, FMTS och I19 där samtliga innehar mångårig erfarenhet av bandvagnssystemet. Formulären kompletteras med intervjuer med dessa personer samt personer på BAE Systems som bidrar med teknisk expertis. Slutsatsen är att seriehybridtekniken har potential att både direkt och indirekt påverka logistikfunktionen positivt, men att konkreta vinster är svåra att bedöma med hänsyn till osäkerheter kopplat både mot tekniska faktorer och att tekniken inte är prövad i strid. / Fossil fuels are finite resources and in a report from 2013, the Swedish Defence Material Administration encourages the Swedish Armed Forces to start planning for the transition to alternative propulsion systems to reduce its dependency of fossil fuels. The most promising technology to bridge the gap between pure electric propulsion and today’s internal combustion engine is hybrid electric technology. This essay examines the implications a series hybrid solution would have on military logistics. The method used includes analysis of both scientific reports and of survey answers from personnel in the SAF with several years of experience working with the tracked vehicle Bandvagn 309. The analysis of the survey answers is completed with interviews with these people and others working at BAE Systems who contributes with technical expertise. The essay will conclude that a series hybrid solution would have a positive impact on military logistics even though it is hard to specify how great the effect would be due to technical uncertainties and the fact that the technology is yet to be tested in combat.
17

Metodologia para simulação dinâmica e otimização de veículos de esteira

Mezacasa, Nathan January 2018 (has links)
Devido as severas condições as quais veículos militares blindados de esteira são submetidos, o desenvolvimento de modelos que representam o comportamento dinâmico destes veículos torna-se imprescindível, para além da possibilidade de avaliação das intensidades das vibrações ocorrendo na cabine, ser possível criar veículos que tenham vantagens na mobilidade, fator esse que engloba tanto a transposição de obstáculos, como a rodagem em condições menos severas, e por fim, no tempo e na exatidão dos disparos, afetada pelas respostas dinâmicas que o veículo fornece. Para ser possível encontrar um veículo que desempenhe tais condições de forma satisfatória, apenas modelos que representem adequadamente as suas propriedades, apresentando respostas das acelerações e deslocamentos, não são suficientes. O objetivo deste trabalho é o desenvolvimento de um modelo numérico que tenha a capacidade de simular as condições dinâmicas extremas as quais um veículo de esteira é induzido, e também, otimizar o modelo, com a finalidade de encontrar molas e amortecedores capazes de proporcionar respostas adequadas às funções custo desenvolvidas. Estas funções objetivo são definidas como a combinação linear da aceleração e deslocamento, verticais e rotacionais, em conjunto de restrições impostas, objetivando encontrar uma combinação ideal para mobilidade, tempo e exatidão nos disparos e por fim, molas e amortecedores adequados as condições de logística Para proposta deste estudo, um modelo matemático 2D e um 3D, de um veículo de esteira, foi desenvolvido. O modelo possibilita a avaliação dos graus de liberdade de deslocamento vertical das massas não suspensas e do deslocamento vertical, arfagem e rolagem da massa suspensa. Os efeitos da esteira são modelados como molas verticais lineares exercendo uma força de restauração para alinhar as rodas de rodagem, proporcional ao deslocamento relativo entre essas rodas. A otimização é feita através de ferramentas numéricas presentes no software comercial Simulink, sendo necessário o desenvolvimento das funções custo que caracterizem os objetivos ideais para cada tipo de análise. Os resultados de simulações numéricas sob a forma de cursos de deslocamento de pontos característicos do casco e deslocamentos dos eixos de rodas em um sistema de coordenadas de referência assumido, também estão incluídos, bem como as quantidades de valor RMS de cada uma das respostas, comparando um veículo padrão, com o veículo com a suspensão otimizada. / Due to the severe conditions in which armored military vehicles are submitted, the development of models that represent the dynamic behavior of these vehicles becomes essential, besides the possibility of evaluating the vibration intensities occurring in the cabin, to be possible to create vehicles that have mobility a factor that encompasses both the transposition of obstacles, and the shooting in less severe conditions, and finally, in the time and accuracy of the shots, affected by the dynamic responses that the vehicle provides. In order to be able to find a vehicle that fulfills these conditions satisfactorily, only models that adequately represent its properties, presenting responses of the accelerations and displacements, are not enough. The objective of this work is the development of a numerical model that has the ability to simulate extreme dynamic conditions such as a tracked vehicle is induced, and also to optimize the model with the purpose of finding springs and shock absorbers capable of adequate alternative answers cost functions developed. These are the goals defined as a linear combination of acceleration and displacement, vertical and rotational, together imposed constraints, aiming to find an ideal combination for mobility, time and precision in the shots and, finally, springs and dampers suitable as logistics conditions To propose this study, a 2D and 3D mathematical model of a tracked vehicle were developed. The model allows the evaluation of the degrees of freedom of vertical displacement of the non-suspended masses and the vertical displacement, pitch and roll of the suspended mass. The effects of the track are modeled as linear vertical springs exerting a restoring force to align the road wheels, proportional to the relative displacement between these wheels. The optimization is done through numerical tools present in Simulink software, and it is necessary to develop cost functions that characterize the ideal objectives for each type of analysis. The results of numerical simulations in the form of displacement courses of characteristic hull points and wheel axle displacements in an assumed reference coordinate system are also included, as well as the RMS value quantities of each of the responses, comparing a standard vehicle with the optimized suspension.
18

Metodologia para simulação dinâmica e otimização de veículos de esteira

Mezacasa, Nathan January 2018 (has links)
Devido as severas condições as quais veículos militares blindados de esteira são submetidos, o desenvolvimento de modelos que representam o comportamento dinâmico destes veículos torna-se imprescindível, para além da possibilidade de avaliação das intensidades das vibrações ocorrendo na cabine, ser possível criar veículos que tenham vantagens na mobilidade, fator esse que engloba tanto a transposição de obstáculos, como a rodagem em condições menos severas, e por fim, no tempo e na exatidão dos disparos, afetada pelas respostas dinâmicas que o veículo fornece. Para ser possível encontrar um veículo que desempenhe tais condições de forma satisfatória, apenas modelos que representem adequadamente as suas propriedades, apresentando respostas das acelerações e deslocamentos, não são suficientes. O objetivo deste trabalho é o desenvolvimento de um modelo numérico que tenha a capacidade de simular as condições dinâmicas extremas as quais um veículo de esteira é induzido, e também, otimizar o modelo, com a finalidade de encontrar molas e amortecedores capazes de proporcionar respostas adequadas às funções custo desenvolvidas. Estas funções objetivo são definidas como a combinação linear da aceleração e deslocamento, verticais e rotacionais, em conjunto de restrições impostas, objetivando encontrar uma combinação ideal para mobilidade, tempo e exatidão nos disparos e por fim, molas e amortecedores adequados as condições de logística Para proposta deste estudo, um modelo matemático 2D e um 3D, de um veículo de esteira, foi desenvolvido. O modelo possibilita a avaliação dos graus de liberdade de deslocamento vertical das massas não suspensas e do deslocamento vertical, arfagem e rolagem da massa suspensa. Os efeitos da esteira são modelados como molas verticais lineares exercendo uma força de restauração para alinhar as rodas de rodagem, proporcional ao deslocamento relativo entre essas rodas. A otimização é feita através de ferramentas numéricas presentes no software comercial Simulink, sendo necessário o desenvolvimento das funções custo que caracterizem os objetivos ideais para cada tipo de análise. Os resultados de simulações numéricas sob a forma de cursos de deslocamento de pontos característicos do casco e deslocamentos dos eixos de rodas em um sistema de coordenadas de referência assumido, também estão incluídos, bem como as quantidades de valor RMS de cada uma das respostas, comparando um veículo padrão, com o veículo com a suspensão otimizada. / Due to the severe conditions in which armored military vehicles are submitted, the development of models that represent the dynamic behavior of these vehicles becomes essential, besides the possibility of evaluating the vibration intensities occurring in the cabin, to be possible to create vehicles that have mobility a factor that encompasses both the transposition of obstacles, and the shooting in less severe conditions, and finally, in the time and accuracy of the shots, affected by the dynamic responses that the vehicle provides. In order to be able to find a vehicle that fulfills these conditions satisfactorily, only models that adequately represent its properties, presenting responses of the accelerations and displacements, are not enough. The objective of this work is the development of a numerical model that has the ability to simulate extreme dynamic conditions such as a tracked vehicle is induced, and also to optimize the model with the purpose of finding springs and shock absorbers capable of adequate alternative answers cost functions developed. These are the goals defined as a linear combination of acceleration and displacement, vertical and rotational, together imposed constraints, aiming to find an ideal combination for mobility, time and precision in the shots and, finally, springs and dampers suitable as logistics conditions To propose this study, a 2D and 3D mathematical model of a tracked vehicle were developed. The model allows the evaluation of the degrees of freedom of vertical displacement of the non-suspended masses and the vertical displacement, pitch and roll of the suspended mass. The effects of the track are modeled as linear vertical springs exerting a restoring force to align the road wheels, proportional to the relative displacement between these wheels. The optimization is done through numerical tools present in Simulink software, and it is necessary to develop cost functions that characterize the ideal objectives for each type of analysis. The results of numerical simulations in the form of displacement courses of characteristic hull points and wheel axle displacements in an assumed reference coordinate system are also included, as well as the RMS value quantities of each of the responses, comparing a standard vehicle with the optimized suspension.
19

Forest Machine Track-Soil Interaction / Spår-mark interaktion hos skogmaskiner

Revathi Palaniappan, Natchammai January 2013 (has links)
I många västeuropeiska länder har metoden för skogsavverkning ändrats från användning av motorsåg till ett mekaniserat skogsavverkningssystem känt som kortvirkesmetoden. Denna metod är baserad på en tvåmaskinslösning – en skördare som fäller, grenar och sågar träden enlig fördefinierade längder, och en skotare som transporterar stockarna till en lastplats för vidare transport till en bearbetningsanläggning. För att utveckla skogsmaskiner som är skonsammare för marken behövs en djupare förståelse av interaktionen mellan terrängen och dragfordonet. Huvudfokus i detta projekt ligger på bandgående skotare.Inom detta projekt, innefattar interaktionen mellan bandet och marken spårbildning, sammanpressning, marktryck, skjuvning, grepp och dragkraft. Spårdjupet är en av de viktiga faktorerna för att bestämma fordonets prestanda och skadeåverkan på mark och vegetation. Mätning och karakterisering av de mekaniska egenskaperna för flersiktade jordlager är en komplex uppgift. De två oftast använda metoderna för att mäta jordens mekaniska egenskaper är Bevametertekniken och Konpenetrometertekniken, där Bevametertekniken är jämförelsevis mindre effektiv för att karakterisera den nordiska skogsträngen eftersom skogsjorden inte är homogen.Olika semiempiriska WES-modeller och parametriska modeller används för bestämmandet av marktryck, spårdjup, dragkraft, rörelsemotstånd och kraften i dragkroken för hjul- och bandfordonen. Beräkningarna utfördes för en skotare av mediumstorlek utrustad med tre olika typer av band monterade på boggihjulen. Detta gjordes för tre olika typer av terrängförhållanden och både med och utan last. Även en jämförelse mellan hjul- och bandfordon gjordes. Resultatet från de teoretiska beräkningarna jämfördes med testdata från ett fullskaligt fältprov. Fältprovet inkluderade data för marktryck, nerträngning i jorden och spårdjup mätt på en skotare, både med och utan last.Adams for Tracked Vehicles (ATV) plugin är ett verktyg primärt utvecklat för dynamiska simuleringar av bandfordon. Fördelar och nackdelar med mjukvaran och dess lämplighet för användning för modellering av interaktionen mellan band och jord for skogsmaskiner diskuteras i denna rapport. / In many Western European countries, the method of timber harvesting has changed from the use of chain saws to a mechanized harvesting system known as Cut-To-Length method. This cut to length method is based on a two-machine solution – a harvester that folds, branches and cuts trees according to pre-defined lengths, and a forwarder that transports logs to a loading area from where it is further transported to a processing facility. In order to develop forest machines that is gentler to the ground, a thorough understanding of the terrain and the vehicle’s traction unit is required. The main focus of this project is on the tracked forest forwarders.In this project, the track soil interaction covers issues like rutting, compaction, ground pressure, shearing, traction and drawbar pull. The rut depth is one of the important factors to determine the vehicle performance and damages caused to the ground and vegetation. Measurement and characterization of the mechanical properties of a multilayer soil is quite a complex task. The two most commonly used methods to measure the soil mechanical properties are the Bevameter technique and the Cone penetrometer technique, of which the Bevameter technique is comparatively less efficient for characterizing the Nordic forest terrain as the forest soil is not homogenous.Different semi-empirical WES models and parametric models are used for the determining the ground pressure, rut depth, tractive force, motion resistance and drawbar pull for the wheeled and tracked vehicles. The calculations were performed for a medium sized forwarder equipped with three different types of tracks mounted on bogie wheels on three types of terrain conditions under loaded and unloaded conditions. A comparison of the wheeled and tracked vehicle performance is also made. The results obtained from the theoretical calculations are compared with the test data from a full scale field test. The field test data include ground pressure, soil penetration and rut depth data measured on the forwarder with and without load.Adams for Tracked vehicles (ATV) plugin is a tool primarily developed for performing dynamic simulations of tracked equipment. The pros and cons of the software and it’s suitability to be used for the track soil interaction modeling of forestry machines is discussed in this report.
20

RC-TMV : Remote Controlled Tracked Multipurpose Vehicle / RC-TMV : Fjärrstyrt Banddrivet Multi Användnings Fordon

Karlén, Anton January 2021 (has links)
This project seeks to design and construct a track-driven radio controlled vehicle and controller. The purpose is to research if radio can be effectively used to control the robot remotely, as well as research to what extent a tracked design increases the mobility when compared to a wheel-design. The prototype consists of two parts: Vehicle and controller. The vehicle is track-driven with two DC-engines connected by H-bridge. A receiver is fitted to the vehicle. The controller consists of two joysticks, a linear potentiometer as well as a transmitter. Testing was performed by driving the vehicle on different terrain.The results show that it is possible to control via RC and that the vehicle had increased mobility compared to wheeled designs. Two problems were identified: Firstly, the tracks used lacks friction, causing the vehicle to glide when attempting to climb certain objects. Secondly, due to the design of the chassis, objects contact the chassis body instead of the tracks. Causing the vehicle to stall. / Detta projekt menar att designa samt konstruera ett banddrivet radiostyrt fordon och tillhörande kontroll. Syftet med detta är att forska om radiostyrning kan effektivt användas för fjärrstyrning och för att undersöka om band-drift ökar fordonets rörlighet jämfört med hjuldrivna motsvarigheter. Prototypen består av två delar; fordon och kontroll. Fordonet är band-drivet med två DC-motorer med högt drivmoment kopplade till en H-brygga. En mottagare är monterad på fordonet. Kontrollen består av två joysticks, en linjärpotentiometer samt en sändare. Testen genomfördes genom att låta fordonet köra över olika terräng. Resultaten av testerna visade att det är möjligt att fjärrstyra med RC samt att fordonet hade ökad rörlighet jämfört med hjuldrivna motsvarigheter. Två problem identifierades under testen. Banden saknar friktion och glider ibland i stället för att klättra över hinder. På grund av chassits form kolliderade ibland objekt med chassit före banden vilket stoppade fordonet.

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