Dissertations / Theses on the topic 'Forklift truck'

Today’s demand on forklift trucks performance and efficiency is high. The productivity is important but also the experience while handling the forklift. The handling has to be simple and genuine to make the driver feel confident and safe. To achieve high performance steering in articulated trucks, a hydraulic power system is often used.Simulation software are a powerful tool in development processes. The program gives the industry a possibility to develop, analyze and evaluate constructions and models more efficient.The purpose of this master thesis is to identify and increase the knowledge about the main challenges in the hydraulic steering system in an articulated forklift. The hydraulic system has been modelled in the simulation software Hopsan and validated against data from measurements performed on the forklift. The different challenges have been identified based on tests and the simulation results. For a deeper understanding of the system a literature study, mainly about the key components, has been done during the master thesis. A number of suggestions for improvement have been developed with focus on increasing the steering performance. The concepts and ideas have been evaluated and tested in the simulation model.The project resulted in a validated simulation model of the articulation and a number of suggested improvements on the hydraulic steering system.

The prevention of incidents and injuries is fundamental for any industry activity since those events may result in serious economic, environmental, and human losses. Due to the centralization of Linde filling operations within Sweden, several of their plants are being phased out to move the production to Enköping. The elevated raise of Linde's production led to a high increase of forklift drivers and stock levels and consequently brought up the number of incidents related to forklift driving. This thesis aims to obtain knowledge to mitigate forklift truck related safety hazards as well as understand how to eliminate risks and unsafe situations at this type of operation. This project was divided into 3 phases. Phase I consisted of understanding operations routines and its safety risks, assessing Enköping site internal state (with a safety survey, and several visits and interviews), and benchmarking the most common practices based on other companies' forklift-related processes (with visits and interviews). In phase II, parallelly to ISite software implementation, studies utilizing different engineering tools (Spaghetti Diagram, VSM, Fishbone Diagram, and FMEA) were performed in order to gather information and understand how to optimize the site's forklift-related safety. In this phase, a tailored observational KPI was developed in order to assess the site independently of incident measurement regarding four groups: Site, Pedestrian activity, Forklift operation, and Forklift operator behavior. In phase III, all data acquired was discussed, and conclusions were made based on the data analysis and discussions of the results of Phase II implementation allied with the theoretical references. The survey findings showed the high degree of importance given to safety at Linde in Enköping. It also revealed, in addition to all engineering tools applied, which elements should be focused in order to optimize the forklift trucks operational safety (mainly related to Technology dimension). Based on the benchmark comparison, it is possible to allege that the absence of a maintenance facility is the main disadvantage of Linde in Enköping. In contrast, the usage of I-Site fleet management software represents an important step towards safety. The I-Site knowledge and the awareness of its benefits grew among management and operators as setup issues, and technical malfunctioning was eliminated. The observational KPI has obtained preliminary overall values above 0,82 for all groups (on a scale of 0 to 1), proving itself capable of measuring the safety performance and identifying risks and unsafe situations.
Att förebygga incidenter och skador är grundläggande för all branschaktivitet eftersom dessa händelser kan leda till allvarliga ekonomiska, miljömässiga och mänskliga förluster. På grund av centraliseringen av Lindes fyllningsverksamheten inom Sverige har flera av deras anläggningar fasats ut för att flytta produktionen till Enköping. Den utökade produktionen på Linde Enköping skapade behov av fler truckförare, högre lagernivåer och ökade följaktligen antalet incidenter relaterade till gaffeltruck. Avhandlingen syftar till att få kunskap för att mildra säkerhetsrisker för gaffeltruckar samt förstå hur man kan eliminera risker och osäkra situationer vid denna typ av verksamhet. Detta projekt delades in i tre faser. Fas I bestod av att förstå driftsrutiner och dess säkerhetsrisker, utvärdera det interna tillståndet på Linde Enköpings arbetsplats (med en säkerhetsundersökning, flera besök och olika intervjuer) och benchmarka de vanligaste metoderna baserat på andra företags gaffeltruckrelaterade processer (med besök och intervjuer). I fas II, parallellt med I-Site-programvaruimplementering, utfördes studier med olika tekniska verktyg (Spaghetti Diagram, VSM, Fishbone Diagram och FMEA) för att undersöka och förstå hur man optimerar verksamhetens gaffeltruckrelaterade säkerhet. I denna fas utvecklades en skräddarsydd observations-KPI för att utvärdera verksamheten oberoende av att mäta incidenter avseende fyra grupper: Plats, fotgängare, gaffeltruck och beteende för gaffeltruck. I fas III diskuterades alla förvärvade data, slutsatser gjordes baserade på dataanalysen och diskussionerna om resultaten av fas II-implementering tillsammans med teoretiska referenser. Undersökningsresultaten visade hur högt säkerhet prioriteras vid Linde Enköping. Den avslöjade också, utöver alla tillämpade konstruktionsverktyg, vilka element som bör fokuseras på för att optimera truckens driftssäkerhet (främst relaterad till teknikdimension). Baserat på den benchmarking som genomfördes är det möjligt att hävda att frånvaron av underhållsanläggning är den största nackdelen med Linde i Enköping. Däremot är användningen av mjukvara för I-Site-flottanhantering ett viktigt steg mot säkerheten. Kunskapen om I-SITE och medvetenheten om dess fördelar växte bland ledningen och operatörerna när installationsproblem och tekniska funktionsfel eliminerades. Utfallen för observations-KPI har erhållit preliminära totalvärden över 0,82 för alla grupper (i en skala från 0 till 1), och visar sig kapabel att mäta säkerhet i genomförande samt att identifiera risker och osäkra situationer.

Fuel economy has become an important consideration in forklift truck design, particularly in Europe. A simulation of the fuel consumption and performance of a forklift truck has been developed, validated and subsequently used to determine the energy consumed by individual powertrain components during drive cycles. The forklift truck used in this study has a rated lifting capacity of 2500kg, and is powered by a 2.6 litre naturally aspirated diesel engine with a fuel pump containing a mechanical variable-speed governor. The drivetrain consisted of a torque convertor, hydraulic clutch and single speed transmission. AVL Cruise software was used to simulate the vehicle powertrain, with coupled Mathworks Simulink models used to simulate the hydraulic and control systems, and fuel pump governor. The vehicle has been simulated on several performance and fuel consumption drive cycles with the main focus being the VDI 2198 fuel consumption drive cycle. To validate the model, a truck was instrumented and measurements taken to compare the performance and instantaneous fuel consumption to simulated values. The fuel injector pump was modified and calibrated to enable instantaneous fuel flow to be measured. The model has been validated to within acceptable limits and demonstrates how the model can be used to compare the fuel consumption and performance trade-offs when selecting drivetrain components.

This thesis evaluates different controllers for traction control on an electric forklift truck and has been done in cooperation with Toyota Material Handling Manufacturing Sweden. The need for a traction control system has increased with the introduction of lithium-ion batteries replacing the older lead-acid batteries, reducing the battery weight and therefore the downward force on the driving wheel increasing the risk for slip. The forklift truck was modelled using Simulink and validated by experiment. Different possible control strategies were investigated and three were chosen for implementation in simulation. These were controllers based on Model Following Control, Maximum Transmissible Torque Estimation and Sliding Mode Control. Model Following Control makes use of a nominal model to compare actual wheel speed values with nominal wheel speed values to determine if slip is occurring, Maximum Transmissible Torque Estimation makes use of a closed-loop disturbance observer to compute the maximum transmissible torque possible without inducing slip and using it as a limitation on the input signal, and Sliding Mode Control uses different functions to \say{slide} along a sliding surface to stay around a specific slip value. All three controller types were developed both as speed controlled and torque controlled. All of the controllers could reduce slip heavily in simulation. The Maximum Transmissible Torque Estimation controller reduced slip the most and kept oscillations at a minimum, but was not as responsive as the others to driver commands. The conclusion was that the controller of choice would depend on the working environment of the forklift truck. In a low friction environment where slip is expected to occur often, the Maximum Transmissible Torque Estimation controller is advisable, while the other two would be a better choice for environment with low slip occurrence. The use of torque control, while often better with regards to decreasing slip, could not be advised due to a perceived increase in implementation cost.

Reach truck masts are subjected to oscillations, which have significant impacts on the dynamics of the entire vehicle. Mast oscillations can cause undesirable outcomes in extreme situations and therefore it is desirable to be able to predict these outcomes before they occur. A forklift manufacturer in Mjölby initiated a thesis with the intention to obtain a model that can simulate mast sway for situations where oscillations occur. The objective of the thesis was to create a model of Triplex masts and find dependencies between model parameters and variables such as fork height and load. The thesis was conducted modelling the mast with a rigid multibody approach where torsion springs and dampers were used between mast parts to simulate mast elasticity. Clearance at the connections were considered and included in the model. The obtained model constitutes of 8 parameters that could be tuned to attain different oscillation characteristics. Parametric optimisation was carried out to find optimal sets of parameters for compliance with sway measurement tests with different load and fork height cases.  The thesis has resulted in a model that is able to simulate mast sway with different oscillation characteristics depending on model parameters. Performed parametric optimisation resulted in parameters that reveal useful information about how model parameters depend on load and fork height. The method used for obtaining optimal parameters can likewise be applied to other mast models in order to gain insight into model parameters as functions of load and fork height.

The purpose of this thesis is to describe the steps undertaken in a “proof-of-concept” project aimed at improving the fuel efficiency of forklift trucks. In this study, a prototype forklift truck was developed which employs a continuously variable hydrostatic transmission in place of the traditional torque converter drivetrain. Through the application of backward- and forward-facing simulation techniques, a novel vehicle control system was created to target maximum drivetrain efficiency, while still working within the constraints of the prototype hardware and the demands of the driver. Different control strategies were designed to optimise the efficiency of the drivetrain in both steady-state and transient conditions, while several performance mode settings were included to allow the driver to adjust the trade-off between fuel consumption and maximum productivity. The prototype truck was tested in accordance with both VDI 2198 and VDI Turnover tests. When the quantity of work was fixed (i.e. during the VDI 2198 test), the control system and its various strategies proved to be functioning as desired by minimising the amount of fuel consumed to complete the task, regardless of the selected performance mode. When the quantity of work was not fixed (i.e. during the VDI Turnover test), a clear trend was demonstrated between fuel consumption and productivity depending on the selected performance mode, again proving that the control system was functioning as desired When compared to the current production truck of the same rated capacity, the prototype truck consumed an average of 36% less fuel over the VDI 2198 cycle. Additionally, the prototype vehicle also showed a 35% increase in effectivity (i.e. the number of loads moved per kilogram of fuel consumed) during the VDI Turnover test Finally, a forward-facing model of the prototype truck was created and partially validated using an industry-standard automotive simulation package with a view to allowing for future developments to be made through detailed vehicle simulation.

ABSTRACT Carton Clamp Test Methodologies and the Effects on Load Containment and Retention Tyler Don Blumer A carton clamp is an alternative device for moving packages and material. Instead of using iron tines like that of a conventional forklift, a carton clamp uses two large aluminum platens to slightly compress and secure the load for handling. This is advantageous as it allows operators to move layers of a unitized load individually, and eliminates the need for a pallet when handling full unitized loads. When using a carton clamp attachment, it is often difficult for operators to accurately gauge the amount of force being applied to the load. The required clamping force changes depending on the size, shape, and weight of the load. This creates the potential for under-clamping (slippage) and over-clamping (compressive damage). Seeing a market need for a reliable means of testing, two organizations set out to develop a testing protocol. A rift formed between schools of thought regarding the correct testing procedure. ISTA provides a sterile, calculated, and stationary simulation of carton clamp handling in its ISTA 6-SAMS test protocol. ASTM offers a more holistic, dynamic, observational approach in its mobile ASTM 6055 standard protocol. One school of thought is suggested to imply that a package should be developed to be handled by the carton clamp (ASTM). The other school of thought is that the carton clamp attachment should be properly adjusted to the package specimen (ISTA). Previous studies have been performed citing the ISTA standard and using a specialized carton clamping device vibration device that is calibrated for laboratory research. Arguably, this method, though repeatable in nature, does not accurately simulate carton clamp handling found in industry. Likewise, the equipment investment is cost prohibitive for those in industry wishing to duplicate such a study. ASTM uses a carton clamp truck as used in industry, but does not specify any specific parameters making repeatability between laboratories and practitioners ambiguous. This study examined whether or not a common ground can be reached; implementing a carton clamp lift truck as found in industry allowing for mobile (hazard course) testing. A modified version of ISTA 3B will be paired off against ASTM 6055 for evaluating both column and cross stack pallet patterns with a variety of treatments. This study attempted to determine if carton clamps as found in industry are capable and repeatable enough to provide consistent data. Similarly, this study examined the test methodologies effect on load containment via stretch film force, load retention via unitized load slippage, and the effects of ride height and driver interaction. The study sought to understand if these effects are uniform across the unitized load, or if particular layers of the load more affected than others.

The project elaborated proposal of comprehensive monitoring of the forklift reconditioning process at the regional refurbishment center for central and east Europe. The proposal aims to increase overall customer satisfaction. The choice of the specific form of monitoring was based on theoretical background and process analysis. Monitoring of process activities is carried out on the basis of barcodes and scanning devices, which are able to distinguish the date and specific time. The proposal results are an overall customer overview increase within process, customer satisfaction increase and support improvement of managing and decision making.

The currently low requirements on sound emissions for industrial trucks are expected to be raised in the near future. The company Kalmar Industries AB, which develop, produce and market industrial trucks, want to improve their truck silencers as a precaution to the future harder restrictions and also to improve their competitiveness. The sound emission produced by a vehicle depends on type and range of application it is designed for but the dominant part of the sound is usually produced by the engine and silencer.

A new measuring method is developed for studying sound emanating through the silencer system. The analysis of the measurement data establishes that the silencers are not working well. The simulations made with SIDLAB, which is a computer programme for calculating the propagation of sound in ducts, confirms that the silencers are inefficient and that they are simply too small.

A simulation which implements a parallel resonator in the main silencer shows that it is possible to make great improvements in reducing the noise from the truck as well as meeting requirements on space.

Mathematical modelling based on linearity and one-dimensional interaction between the silencer elementsis advantageous and gives very good results when understanding, analysing and simulating the silencer. The simulation tool SIDLAB works well and saves a lot of time by its fast modelling and easy interface.

This master thesisinvestigates the possibilities to implement a digital filter for wire guidancein a truck. The analog circuits in the truck, today, are analyzed to understandtheir signal processing. The component MAX261 is especially interesting and itis analyzed in a special Section to make sure that all needed details, todevelop a digital filter, are available. When all theoretical calculation wasfinished, all the circuits were simulated to make sure that the calculationsare correct.   The digital filter is based onan analog filter which is expensive and not so easy to purchase. A requirementspecification was developed by analysis of the properties of the analog filterand how it is currently used. The analog filter is a part of a chain of analogsignal processing which mostly can be performed digitally instead.   The special type of the analogfilter makes the requirements, on the digital filter, very tough and anextensive analysis of digital filter structures was performed in order to finda suitable filter. The digital filter is of WDF (Wave Digital Filter)-type andit is very special, because it has two variable coefficients, one for thesteepness and one for the center frequency. The digital filter consists of anumber of first order filters, because a higher order filter with desiredproperties has coefficient values that are large which makes the stabilityproperties worse.   The best type ofimplementation of this filter and the signal processing are also analyzed.Finally, a prototype was developed on a development board where the maincomponent is a DSP (Digital Signal Processor). The program for the prototype iswritten in C-code and the performance of the system was verified by differenttests and measurements.

Wireless technologies and networks are a part of our daily lives and we are surrounded by a constant stream of wireless signals. Unfortunately, there are a lot of limitations. At Toyota Material Handling Europe, future demands and expectations are raising but the technologies available today are not adapting fast enough. Indoor factory environments, moving network nodes and rapidly changing topologies are demanding situations. In this new Internet of Things day and age, transferring information in these challenging environments, the standard master and slave configuration is not enough. This report looks at the specific challenges establishing a wireless communication link between trucks in an indoor factory and warehouse environment. There are many factors to consider. Antennas, noise, frequency bands, different network technologies, propagation and path loss modeling to mention a few. Antennas and on-the-truck antenna positioning require design choices to be made. If we want to benefit from using high gain antennas, positioning is an important factor. Noise, in the highly congested 2.4 GHz band is a problem, especially considering safety critical applications. The license free ISM frequency bands have all different advantages in range, available communication protocols and amount of other technologies sharing the spectrum. The Wi-Fi, Bluetooth, ZigBee and V2X technologies looked at, tailored to the particular case of a warehouse environment like the Toyota factory, and the final selection relates to potential use case scenarios. Prioritizing, scalability, ad hoc network topologies, low latencies and short connection times together with long range, the new V2X technology building upon the IEEE 802.11p standard stands out. This report evaluates the IEEE 802.11p wireless standard running the ETSI ITS G5 V2X protocol in an indoor factory and warehouse environment. Thanks to Kapsch and their EVK-3300 V2X Evaluation Kit it was possible to evaluate transferring information between nodes, the PSR, and looking at how useful different path loss models are for estimating relative distances between trucks.

This is a final thesis done at BT, considering one of their forklift truck models called Reflex. The first part of this report is about a preliminary investigation investigating what kind of diagnostic systems BTwants to use, and also which demands there are to meet all expectations on such system. Secondly a diagnostic system, which will show if the drive wheel is worn out, will be presented.

In the preliminary investigation, two kinds of diagnostic systems were mentioned. These were Model based diagnosis and Predictive analysis. Model based diagnosis is based on measurements made by sensors at the truck, while predictive analysis is based more on statistics and retrieved data about the lifetime of a truck in specific environments.

The diagnosis system for the drive wheel is based on a model made in Matlab's Simulink. Due to poor documentation, rough simplifications in the model have been made. However, one can still see the differences of principle.

The main thought was detecting a difference in the lowest torque level from the engine, varying the diameter of the drive wheel. By measurements made directly at the truck, different torques could be observed with varying diameter of the drive wheel, varying load on the truck and varying friction in the gearbox. Using hypothesis tests, it is possible to say whether the drive wheel is worn out or not.

Results show that if the drive wheel diameter is reduced by 25 mm, torque is reduced by 7% and if the drive wheel diameter is reduced as much as 50 mm, a torque reduction of 11% would be achieved.

This thesis explains the model-based design of a fork control system in a turret head operated Very Narrow Aisle forklift in order to evaluate and push the limits of the current hardware architecture. The turret head movement consists of two separate motions, traversing and rotation, which both are hydraulically actuated. The plant is thoroughly modeled in the Mathworks softwares Simulink/Simscape to assist in the design of the control system. The control system is designed in Simulink/Stateflow and code-generated to be evaluated in the actual forklift. Optimal control theory is used to generate a minimum-jerk trajectory for auto-rotation, that is simultaneous traversing and rotation with the load kept in centre. The new control system is able to control the system within the positioning requirements of +/- 10 mm and +/- 9 mrad for traversing and rotation, respectively. It also shows good overall performance in terms of robustness since it has been tested and validated with different loads and on different versions of the forklift. However, the study also shows that the non-linearities of the system, especially in the hydraulic proportional valves, causes problems in a closed-loop control system. The work serves as a proof of concept for model-based development at the company since the development time of the new control system was significantly lower than for the original control system.

Syftet med examensarbetet var att översiktligt undersöka vilka hälsofarliga luftföroreningarsom medarbetarna vid hamnmagasinen eventuellt exponeras föroch huruvida något hygieniskt gränsvärde riskerade att överskridas samt att seom de skyddsåtgärder som vidtagits kan förbättras. Resultatet från studien visaratt det finns vissa exponeringsrisker för de som arbetar vid hamnen både frångods, dieselavgaser samt rester av gasbehandlingsmedel i containrar.Arbetsmomenten där truckföraren befinner sig inne i trucken bedöms somrelativt skyddat både från partiklar och gaser, men det finns andra arbetsuppgifterdär arbetaren inte är lika skyddad. Mätningarna av kvävedioxid visadeatt exponeringen av dieselavgaser för den medarbetare som öppnadecontainrarna inte översteg några hygieniska gränsvärden, under de dagar sommätningarna genomfördes, men var något högre än för truckföraren som satt ihytten. Huruvida exponeringen av damm från gods riskerar att utvecklas tillhälsoproblem är omöjligt att avgöra utan en grundlig riskbedömning, därdammätningar kan ge en fingervisning om hur riskfylld situationen är för desom eventuellt exponeras.Organisationen bör implementera säkrare rutiner och genomföra åtgärder sommotiverar medarbetarna att använda befintlig skyddsutrustning. Det gäller intebara för exponering av dieselavgaser och damm från lossning och lastning avgods utan även vid öppnandet av containrar där rester av gasbehandlingsmedelkan finnas kvar i containern och där några ämnen misstänkts varacancerframkallande.Slutsatser: Genomföra en grundlig riskbedömning och kartlägga möjliga hälsoriskerkring luftföroreningar. Upprätta skriftliga arbetsbeskrivningar där eventuella risker föreligger. Installera ventilation i magasinen som styrs av halten kvävedioxid för attsäkerställa att höga halter av dieselavgaser inte uppstår. Behov av motivationshöjande insatser kring säkerhetskultur ochanvändningen av skyddsutrustning. Implementera fungerande rutiner som följer lagstiftningen förhanteringen av damm och gaser som gäller för cancerframkallandeämnen.
The purpose of this thesis was to examine the risk of hazardous air pollutantsthat employees at the harbor may be exposed to and assess whether anyexposure limits might be exceeded, and to review if the security measures taken,can be improved. The results of the study show that there is some risk ofexposure for those working in the harbor from both the cargo, diesel exhaustand residues from fumigants in the containers. The operations when the truckdriver is inside the forklift is considered relatively protected from both particlesand gases, but there are other tasks where the worker is not as protected.Measurements of nitrogen dioxide showed that exposure to diesel exhaust forthe employee who opened the containers during the days that the measurementswere performed did not exceed some critical values, but was slightly higherthan for the driver who was sitting in the forklift. Whether the exposure to dust,from the cargo, constitutes a risk for health effects is impossible to determinewithout a thorough risk assessment, where measurements of dust can give anindication of how risky the situation is for the exposed workers.The organization should implement safer practices and implementing measuresthat motivates employees to use existing protective equipment. This applies notonly for exposure to diesel exhaust and dust from loading and unloading ofgoods, but also at the opening the doors on the containers in which residues offumigants, in which some are suspected to be carcinogenic, can remain in thecontainer.Conclusions: Conduct a thorough risk assessment and identify potential health riskswith air pollution. Establish written work instructions where potential hazards exist. Install ventilation in the warehouses, which is controlled by the levels ofnitrogen dioxide, to ensure that high levels of diesel exhaust does notoccur. Need to increase motivation for safety and the use of protectiveequipment. Implement procedures to comply with the legislation for the managementof dust and gases that applies to carcinogens substances.

Vehicles are becoming increasingly autonomous, as automotive industries are investing in innovative technology. Therefore the technology becomes more available and affordable, making it possible for Toyota Material Handling Europe (TMHE) to introduce automated features in their trucks. Vehicles that have a forward collision warning system, and thus are partly autonomous, are involved in less accidents than those without. In manufacturing industries there is currently a problem with truck collisions and an automated solution might be a suitable way to prevent these. When implementing an automation device, human machine interaction and user-friendliness are aspects to keep in mind during the development. The thesis concerns how autonomous features can assist the truck driver, and how to provide the driver with intuitive feedback. The purpose was to ensure the drivers’ and surrounding personnel’s safety as well as increase the productivity. Research was performed regarding in what situation an assisting device is needed and how to communicate information in an intuitive manner to help the driver in this situation. A conceptual interface was developed that allows communication between the driver and a future all-knowing system, that tracks all objects and personnel in a warehouse. The drivers have had a central role in the process. The observations were performed in the TMHE warehouse to identify situations. The most perilous and frequent situation was when drivers need to focus both in the fork and drive wheel directions simultaneously. This either puts the surroundings or the driver in danger. A conceptual interface was developed to help the driver in this situation. This resulted in a concept implementable in both current and future trucks, to harmonise the solution and ensure a safe warehouse environment. A lo-fi prototype was constructed and evaluated iteratively with drivers to ensure the quality and usability of the concept. The resulting feedback solution consists of sounds from speakers mounted in the headrest and a display interface with warning symbols. The sounds are directional to notify the driver if the danger is to the left or right behind his back. If the danger is only semi-close, the driver receives a warning, but if it is very close, the truck is stopped autonomously. The symbols appear on the display simultaneously as the sounds are heard, to provide further feedback. Additionally, an Autonomous Positioning feature has been developed, that consists of symbols and buttons on the display interface, as well as an alert sound from the display to indicate the system’s activation and deactivation. Safety is enhanced since neither personnel nor trucks are in risk of collision when implementing the concept. As the concept helps the driver position the truck effortlessly towards the pallet the productivity is also improved.

Unique customizations (options) of features in forklifts are often requested by customers. When new options are created or existing options have to be modified in the main software the complexity increases, the firmware revision pool gets large and with the increasing code size the memory limit is threatened. This affects the software development since the frequent modification of the option handler software is very resource consuming. Therefore it is desirable to have a highly modular system for the option handler to simplify the development process. Although the market value of this improvement is negligible the possible long term savings is the desirable effect. This thesis explores the possibility of migrating the option handling software to a dedicated hardware module. This helps the development process by increasing the modularity of the system architecture and thus reducing the development scope. The tools and the approach to accomplish this option handler is analyzed. A system model of the resulting approach is designed and a prototype is developed to validate the result.

Master thesis concerns with a design of forklift truck. The result proposed in the thesis uses existing technologies but combines them in new context to gain better qualities of a lift truck especially in relation to user-friendliness and ergonomics. Shaping works on functional demands which are understood as a basis for further developments towards the aesthetical outcome.

Standup forklift trucks are extensively used primarily for material handling in high density warehouses. These forklifts over the years have been involved in severe accidents causing injuries and taking lives of the operator and that of people on the floor. The major accidents involving these trucks are tip-over, off the dock accidents, compartment intrusions and under the rack injuries. The objective of the work is to analyze the accident data and to provide a conceptual design to ensure safety of the operator riding the standup forklift trucks. The operator is assumed to be safe when retained within the compartment similar to that of the safe space environment of a sit down forklift truck or tractors. Thus a door on the standup forklift would provide a safer compartment. This design would help in preventing severe injuries to the operator in case of any accidents. The important criterion of this design is to provide a door with latch and slide mechanism to ensure easy egress and ingress of the operator. The compartment is designed ergonomically for 95th percentile industrial male population. The accident data is studied by performing statistical and failure analysis. Weibull plots are fitted for life time distribution data and are found to be of increasing rate. This suggests that present safety precautions are increasingly ineffective.

碩士
國立交通大學
控制工程系
85
Over recent years, there has been an increase in the number of overturn accidents of fork-lift trucks. In most case, the driver was killed or seriously injured. To protect the operator, the Inst. of occupational Safety and Health has initiated a project of a suitable warning device to prevent these accidents. This thesis is the third year project. The goal of this thesis is to made a model of a fork-lift truck using few parameters. Special attention will be paid in realization of the overturning conditions from both software and hardware point of view. Secondly, a warning device based on the consideration of cost effectiveness will be made with proper sensor signals. These signals are processed through a microprocessor using fuzzy logic to give out warning signals, both in lighting and voice forms. A scaled fork-lift model will be built to verify and improve the capability of the device.

碩士
南臺科技大學
電機工程系
105
In this thesis, an algorithm is proposed for line tracking and object recognition by using an Arduino controller and a Pixy camera. With the application of a differential-driven wheeled robot, it is possible to track lines and recognize objects which can all be implemented in the industry such as unmanned forklift trucks. The proposed algorithm takes central points by a forward facing pixy camera, in order to perform the movement of tracking successfully with the correlation of a wheeled robot. By tracking the red color, the pixy camera can identify which path to follow, distinguishing the bright hue over the contrast color of the floor which avoids confusions. Labeling the objects with a specific color allows pixy camera to understand which object is the target one. Dynamics of the wheeled robot are also studied to avoid any unbalance or problem with the different maneuvers that can be present during line tracking. Basing the studies on articulated vehicles, the research is developed in order to be implemented in many other scenarios in automated vehicles. Keywords: line tracking, object recognition, pixy camera, differential-driven wheeled robot

There has recently been an increased interest in hydrogen, both as a solution for seasonal energy storage but also for implementations in various industries and as fuel for vehicles. The transition to a society less dependent on fossil fuels highlights the need for new solutions where hydrogen is predicted to play a key role. This project aims to investigate technical and economic outcomes of different strategies for production and storage of hydrogen based on hydrogen demand and source of electricity. This is done by simulating the operation of different systems over a year, mapping the storage level, the source of electricity, and calculating the levelized cost of hydrogen (LCOH). The study examines two main cases. The first case is a system integrated with offshore wind power for production of hydrogen to fuel the operations in the industrial port Gävle Hamn. The second case examines a system for independent refueling stations where two locations with different electricity prices and traffic flows are analyzed. Factors such as demand, electricity prices, and component costs are investigated through simulating cases as well as a sensitivity analysis. Future potential sources of income are also analyzed and discussed. The results show that using an alkaline electrolyzer (AEL) achieves the lowest LCOH while PEM electrolyzer is more flexible in its operation which enables the system to utilize more electricity from the offshore wind power. When the cost of wind electricity exceeds the average electricity price on the grid, a higher share of wind electricity relative to electricity from the grid being utilized in the production results in a higher LCOH. The optimal design of the storage depends on the demand, where using vessels above ground is the most beneficial option for smaller systems and larger systems benefit financially from using a lined rock cavern (LRC). Hence, the optimal design of a system depends on the demand, electricity source, and ultimately on the purpose of the system. The results show great potential for future implementation of hydrogen systems integrated with wind power. Considering the increased share of wind electricity in the energy system and the expected growth of the hydrogen market, these are results worth acknowledging in future projects.