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Introduction
Publications
Publications (96)
A load sensing (LS) supply in combination with control valves is one of the most common solutions for the actuation of implements on heavy-duty mobile machines (HDMMs). A major drawback of this approach is its relatively low energy efficiency due to metering losses—especially for multi-actuator operation and load braking. Several novel, more effici...
Rethinking Autonomy and Safety: SAAN White Paper
In this paper, we propose a new algorithm for data extraction from time-series data, and furthermore automatic calculation of highly informative deep features to be used in fault detection. In data extraction, elevator start and stop events are extracted from sensor data including both acceleration and magnetic signals. In addition, a generic deep...
The optimisation of load shares between parallel power sources is essential for fuel-efficient propulsion systems. A more complete power management problem can be formulated by including the propeller and its propulsion control. Not only does this allow for a reduction in the propeller load under the changing operating conditions of the vessel, but...
In the early stages of the ship design process, the system designer must choose which type of machinery system will be used to power the ship. Hybrid power systems, which are familiar in the automotive industry, have started making a breakthrough in the marine industry. However, defining the length of the financial payback period is not trivial for...
A novel hydraulic-mechanic damper was designed and dimensioned for damping of ice loads of a steerable thruster. The system consists of inertia masses and four hydraulic cylinders acting as spring and damping elements. The system is energy self-sufficient and fail-safe. Simulation model is used to study the damping potential and applicability of th...
The conventional marine vessel power systems typically have the potential to improve their fuel consumption and their emissions. This can be done by redesigning the system configuration, the machinery and the power management strategy. The addition of options in power management allows for the running of individual power sources closer to their opt...
In this paper, we study the diagnostics and identification of injection duration of common rail (CR) diesel pilot injectors of dual-fuel engines. In these pilot injectors, the injected volume is small and the repeatability of the injections and identification of the drifts of the injectors are important factors, which need to be taken into account...
In this paper, we address the problem of identification of injection duration of common rail (CR) diesel pilot injectors of dual-fuel engines. In these pilot injectors, the injected volume is small and the repeatability of injections and identification of drifts of injectors are important factors, which need to be taken into account in order to ach...
Steerable thrusters are used to maneuver a vessel in open sea environment. The harsh environment of arctic seas introduces certain challenges with propellers hitting ice and decreasing lifetime of the system, as the loads generated by ice impacts are significantly higher than nominal loads. Damping of an ice impact load is a difficult task since th...
The decentralisation of hydraulic systems is a recent trend in industrial hydraulics. Speed variable drive is one concept where an actuator is driven by an integrated pump, thus removing the need for control valves or complex centralised variable displacement hydraulic units and long pipelines. The motivation for the development is the need to impr...
In this paper, a velocity tracking controller for hydrostatic drive transmissions is developed. The solution is based on a state-dependent model that incorporates nonlinear characteristics of the system. A full state feedback controller is devised and the gains are scheduled on measured speed and pressures, together with approximated volumetric flo...
The work behind this paper took place in the Eurofusion remote maintenance system project (WPRM) for the EU Demonstration Fusion Power Reactor (DEMO). Following ITER, the aim of DEMO is to demonstrate the capability of generating several hundreds of MW of net electricity by 2050. The main objective of this paper was the study of the most efficient...
In this study, we design a fuel optimal controller for hydrostatic drive transmissions (HSD) that significantly improves their fuel economy. Contrary to great proportion of the literature, efficacy of the controller is demonstrated by real machine implementation equipped with online fuel consumption measurement system. The main control objective of...
This paper presents a model-based control solution for large inertia systems controlled by a fast digital hydraulic valve. The solution is based on model-based force control and it is shown that the cylinder chamber pressures have first order dynamics with the proper parameter selection. The robust stability is analyzed under unknown load mass, bul...
Energy efficiency of hydraulic machinery is an important trend. Another trend is more automatic machines, which sets new demands for the controllability of hydraulic actuators. High-performance distributed valve systems can satisfy these requirements. Recently, the authors have developed a new high performance digital hydraulic tracking control sol...
The Digital Hydraulic Power Management System (DHPMS) is a multi-outlet alternative for conventional variable displacement pump/motors. Based on the digital pump/motor technology, the DHPMS have the potential for good efficiency; the valve timing can be optimised for each pressure level and displacement is controlled by leaving some of the pumping...
The automation of hydraulic mobile machinery, such as excavators, requires high performance control solutions. In hydraulics, this means fast and accurate force, velocity and position control of hydraulic cylinder. Especially the force control is known to be difficult with traditional servo valves. Fast digital hydraulic valves together with modern...
In this paper, we address the problem of diagnostics of mobile hydraulic work machines. A diagnostics method based on the comparison of measurement data of a HIL-simulator and a real mobile work machine using a real time simulation model of an articulated-frame-steered wheel loader is presented. The proposed method includes two phases: training and...
Hybridization of heavy off-highway working vehicles brings considerable energy savings in the form of a downsized internal combustion engine (ICE) by means of reduced no-load losses. In this paper, a novel energy saving opportunity in working hydraulics at the end of long booms of working vehicles is proposed. In traditional off-highway working veh...
Digital hydraulic valve system is a new kind of hydraulic control valve assembly, which has potential to save energy and improve performance of valve controlled actuators. The typical digital valve system has 4-6 parallel connected on/off valves per control edge totaling 16-24 valves in the four-way valve configuration. The flow capacities of the p...
Previous research on digital fluid power indicates down-scaling to be beneficial to the characteristics of digital valves. This theoretical aspect yields to use equal size on/off valves in digital hydraulic valve systems. A simple miniaturized on/off valve, having orifice diameter of 0.7 mm, have been developed to study the feasibility of this appr...
Diesel engines are widely used due to their high reliability, high thermal efficiency, fuel availability, and low consumption. They are used to generate power, e.g., in passenger cars, ships, power plants, marine offshore platforms, and mining and construction machines. The engine is at heart of these applications, so keeping it in good working con...
Digital design and virtual engineering are nowadays the means for efficient machine design and product development. However, the full potential of the simulation-based approach has not been exploited.
At the time of writing this SIMPRO project final report, Finland is going through a period of economic recession, and all the sectors are trying to...
Mobile multimachine work environments, in general, consist of varying types of machines driving across a site to complete a moving or manipulation task. As the view from the machines over the environment can be limited due to the structure of the machines, the environment, and the moved/manipulated items, there is a risk of collision between machin...
The paper describes a concept design of a remote handling (RH) system for replacing divertor cassettes and cooling pipes in future DEMO fusion power plant. In DEMO reactor design important considerations are the reactor availability and reliable maintenance operations. The proposed divertor mover is a hydraulic telescopic boom driven from the trans...
Autonomous mobile machines use onboard sensors for navigation and obstacle avoidance. The accuracy of the sensor data in global frame is however dependent on the localization accuracy of the machine. Simultaneous localization and mapping algorithms (SLAM) are widely used with 3D laser scanners for mapping the world. They use scan matching algorithm...
This paper presents and analyzes a hybrid solution, in which the hydraulic energy storage element is integrated to the hydraulic actuator. The approach results in a new system layout–a distributed hybrid system–in which only mean power is transmitted between the actuators and the high power peaks are handled locally. Three different implementations...
Model-based control algorithms of digital hydraulic valves offer optimized control performance, but are computationally heavy. Research work has been carried out using PC hardware such as dSPACE real-time systems. In order to apply digital hydraulic valve control in real, series production application, the algorithms should be redesigned such that...
This paper proposes a new efficient path-planning algorithm for articulated steering vehicles operating in semi-structured environments, in which obstacles are detected online by the vehicle's sensors. The first step of the algorithm is offline and computes a finite set of feasible motions that connect discrete robot states to construct a search sp...
In this paper, we present anomaly detection and diagnostics for articulated frame steered hydraulic wheel loader. The presented methodology is based on the analysis and comparison of the responses of a dynamic mathematical model and a real wheel loader using a joint probability distribution of correlation coefficients of multiple variables. The beh...
The Digital Hydraulic Power Management System (DHPMS) is a solution based on the digital pump-motor technology and has shown to be a promising approach to improve the energy efficiency of hydraulic systems. The DHPMS is controlled by active on/off valves, but unlike the digital pump-motors the DHPMS has multiple independent outlets; hence, the DHPMS...
This paper presents an optimal controller for fuel efficiency of a hydraulic mobile machine with hydrostatic drive (HSD). The solution is validated using a semi-empirical simulated research platform. The drive transmission of the machine includes one variable displacement hydraulic pump and four two-speed hub motors. There is no energy storage inst...
This research presents method for the online estimation and prediction of drive forces in heavy duty vehicles. The estimation is based on the measured velocity and longitudinal dynamics. The same method can be applied for the prediction but the reference velocity is given as the input of the system instead of actual velocity. The prediction and est...
Hydraulic fluid is one of the most important components in every fluid power system. Therefore, fluid properties have to be known with a good accuracy in an increasing number of applications, for example in system’s design, modelling and control. The fluid of interest may be a power transmission fluid as well as a fuel. In defining the needed fluid...
This study focused on the use of fixed displacement pumps in parallel connection to control the velocity of a multi-chamber cylinder piston. The system’s basic principle was to combine the discrete flow supply control of parallel pumps with the discrete effective area control of a multi-chamber cylinder to produce a speed control resolution high en...
Hydraulic motion control is traditionally done with servo or proportional valves. A digital hydraulic valve is based on arrays of simple on/off valves. Independent metering control is possible with digital valves since control notches are not linked together. With commonly used commercial proportional valves constant opening ratios are used. In thi...
This article suggests a novel path planning algorithm for a non-holonomic wheeled vehicle operating in a semi-structured environment. The first step of the algorithm is to compute offline a finite set of feasible motions connecting discrete robot states to construct a search graph. The motion primitives based on Bézier curves are generated by solvi...
After several years of study, a large bore diesel engine Electro-Hydraulic Valve Actuation (EHVA) system has reached a development point where the system has been successfully used for years in laboratory test engine environment too. During the evolution of the EHVA, insight of the hydraulic and control systems features has been cleared. This paper...
A combination of digital hydraulic four notch control valves and the digital hydraulic power management system (the DHPMS) has many controller levels, both parallel and series. The DHPMS is a multi-port sink/source of hydraulic power. Digital hydraulic valves are used to control the actuators. Both the DHPMS and the digital valves are based on the...
Earlier simulations as well as measurements have shown the potential of the Digital Hydraulic Power Management System (DHPMS). The machine can function as a pump, a motor and a transformer, and due to multiple independent outlets, actuators with arbitrary pressure levels can be efficiently served. In addition, pre-compression and pressure release p...
This paper presents a novel procedure for using R&D simulators to support planned maintenance of mobile work machines. R&D simulators are usually made and used during the designing phase of products. After the final product has been released to market, simulation models are not effectively utilized at later stages of the life cycle, although there...
The usage and control of combustion engines has a significant effect in the fuel consumption and controllability of mobile work machines. In general, the best efficiency region of engine is at high partial loads. In this area, the challenge is the reduced reaction speed of engine. In this paper, we present an approach to gain high fuel efficiency a...
This paper addresses a visual servoing problem for a mobile manipulator. Specifically, it investigates pallet picking by using visual feedback using afork lift truck. A manipulator with limited degrees of freedom and differential constraint mobility together with large dimensions of the machine require reliable visual feedback (pallet pose) from re...
In this paper, a second order polynomial model for predicting the pressure-temperature behaviour of the density of any hydraulic fluid is presented. The model is an extension of the previously published model by the same authors for more moderate operating temperatures. Nevertheless, for a user the extension will not add any more complexity to the...
Hydraulic systems are widely used in working actions of mobile machines. They offer good power to weight ratio, robustness and relatively good controllability. However, there has been growing interest on the energy efficiency of such machines during recent years. Load sensing proportional valve control is a typical solution for multi-actuator syste...
In this paper, the operating states of a wheel loader were studied for diagnostics purposes using a real time simulation model of an articulated-frame-steered wheel loader. Test drives were carried out to obtain measurement data, which were then analyzed. The measured time series data were analyzed to find the sequences of operating states using tw...
Dynamic properties of hydraulic fluids have to be taken into account in ever increasing fluid power applications. The main reasons are increasing accuracy demands in control and modelling, as well as increasing operating pressure and temperature ranges. Moreover, the already wide spectrum of different hydraulic fluids is also expanding all the time...
This paper discusses the general characteristics of digital hydraulic power management
system. The principle is new and studied only in few research publications.
Functionality, controllability and losses are discussed, and the conclusion is that the
technology makes almost optimal power management possible. The technology also
improves the ene...
The digital pump-motor-transformer is a new energy-efficient alternative to the fluid power system. Based on digital (stroke to stroke) control of each piston of the pumping unit, its functionality consisted of (1) an arbitrary number of independent outlets, (2) service of each outlet at arbitrary pressure levels, (3) energy recovery from each outl...
In this paper I aim to explain how important is to reach an optimal synchronization between Control Station (CS) and Mobile Machine (MM). In this research synchronize means to give a correct order to all the elements involved during data acquisition and transference in the teleoperation process. Also the synchronization process includes the policy...
This paper addresses the problem of autonomous control of a hydraulically actuated articulated-frame-steering (AFS) mobile machine- a wheel loader. Our autonomous motion control system includes a mission planning graphical user interface, an improved odometry algorithm and a GPS device for navigation purposes, together with a model based path-follo...
The variable gas exchange valve actuation systems have been developed in order to improve the efficiency of the combustion process. The electro-hydraulic valve actuation (EHVA) systems have good power to weight ratio, high maximum force and good controllability. The disadvantages are limited frequency bandwidth and energy recovery. Each component o...
This paper is the next stage in the result of my research in wireless teleoperation on hydraulic mobile machines. In this paper I aim to explain the benefits of using a multi-packet protocol versus a mono-packet protocol. During my research work the system has been updated from the mono-packet protocol to the multi-packet protocol to provide the sy...
This paper is a step forward in my research work about creating more intelligence in wireless teleoperation on hydraulics mobile machines. This paper deals with the importance of synchronization in the data transference between different elements to provide a reliable connection during the teleoperation process. A new module (G.P.S. receiver) is in...
This paper suggests second order polynomials for modeling hydraulic fluid dynamic properties — tangent bulk modulus, density and speed of sound in fluid. Model parameters can be calculated from ISO fluid characteristics data available for every commercial hydraulic fluid. The accuracy of the models is verified with measurements at pressures up to 1...
Remote control is often considered as a means of utilization when operating hydraulic mobile machines in hazardous environments. However, in some cases remote control may also improve the general usability of the machine, which is a good reason for using remote control also in normal (safe) work tasks. In this paper the effects of remote control on...
This paper is a step forward in my research work about using wireless teleoperation on hydraulics mobile machines. This paper deals with the importance of data acquisition from and to the mobile machine and the ways of displaying the information for the teleoperator in control station. The paper also explores a set of possible errors occurring duri...
Remote control of hydraulic mobile machines is often used because of safety issues. In addition to safety, remote control can be used to improve working efficiency and usability of the machine. A prototype of a hand-held remote control is designed to be used as a user interface of a mobile machine with an excavator while the machine is controlled r...
Autonomous functions are a common research topic in robotics. However, the robots typically have limited operating conditions and they can only handle relatively small loads. Many autonomous control concepts are applicable to actual construction machinery. The benefits would be considerable regarding efficiency, safety, and operator comfort. The re...
Future Worksite is a concept for robotic work machines working together in a common worksite. Newly founded GIM-Institute studies the subsystems and technologies in the area of field and service robotics. Research results are demonstrated and tested with real machines in the GIM-worksite, which is equipped with several robotic work machines, suppor...
Electro-Hydraulic Valve Actuation (EHVA) is one of the most promising ways to improve the performance and reduce the emissions of the diesel engines. The EHVA gives fully variable lift and event duration of the gas exchange valves and thus the combustion process can be better controlled in different operation points such as idle and partial load si...
This paper presents an experimental study of the correlation between rail-to-injector connection pipe geometry (3 lengths and 3 diameters) and pressure oscillation characteristics (amplitudes, mean pressure drop, frequency, damping of the oscillation) and injected volume, respectively. The injection input parameters are based on a single injection...
This article presents the measurement results of an RPM-regulated compressor transmission equipped with an overriding drive. The function principle and the construction parameters of the overriding drive is presented in part 1 of this article "CVT compressor drive". In contrast to the measurements in the first article, the transmission presented in...
This paper investigates the source of pressure fluctuations in a common rail (CR) system for high speed diesel engines as a function of injection parameters and system design (pipe between rail and injector). The pressure values are recorded experimentally at the inlet of the injector. In addition, a simulation model has been developed. The paramet...
Attachments and their controls can be connected to hydraulic mobile machines in different ways. The traditional approach is to install hydraulic valves of the attachment close to the operator. Thereby levers of the valves can be reached from the operator seat. This, however, restricts the size and number of the valves and can be inconvenient for th...
A small general-purpose teleoperated hydraulic mobile machine is studied at the Institute of Hydraulics and Automation at the Tampere University of Technology. Thanks to teleoperation, the operator of the machine is able to be in safe place during the driving when necessary. However, the actions of the machine can be dangerous for the people or the...
The goal of the paper is to study the properties of a teleoperated mobile machine and produce a simulation model of the machine for later use. In this paper there are introduced a prototype of the teleoperated mobile machine and a simulation model of that machine. The challenge in teleoperation is to have a smooth and accurate control of the machin...
The mobile machine subject to study is a skid steered loader equipped with boom and bucket. In order to teleoperate the mobile machine, two operator-machine interfaces, which take into account the special requirements of hydraulic machines, have been designed and tested. The operator-machine interfaces are implemented in a laptop computer equipped...
The purpose of this study is to develop steady-state models of the components of the hydrostatic transmission and both linear and non-linear dynamic models of a hydrostatic transmission system. The simulation models of different hydraulic components and the complete hydrostatic transmission system including diesel engine are verified with measured...
A modern hydrostatic transmission consists of three main
components, a diesel engine, a variable displacement hydraulic pump and
a variable displacement hydraulic motor. The output speed of the
hydrostatic transmission is controlled by governing the rotational speed
of the diesel engine and controlling displacements of the hydraulic
units. Traditio...
A real time simulation technique is described and illustrated with reference to a hydraulically controlled crane. This minimizes simulation time and can be further boosted by preliminary control based on estimation. Simulation of servosystems takes longer than in the case of systems of relatively high time constants. (R.Hardbottle)
A small general-purpose teleoperated hydraulic mobile machine is studied at the Institute of Hydraulics and Automation at the Tampere University of Technology. The boom and the bucket of the machine are normally controlled with a joystick. Horizontal movement of the joystick controls the bucket and vertical movement controls the boom. An angle of t...