Search results for "Loader"
showing 10 items of 14 documents
Minimal-model for robust control design of large-scale hydraulic machines
2018
Hydraulic machines are in use where the large forces, at relatively low velocities, are required by varying loads and often hazardous and hard-to-reach environments, like e.g. offshore, mining, forestry, cargo logistics, and others industries. Cranes and excavators equipped with multiple hydraulic cylinders are typical examples for that. For design of the robust feedback controls of hydraulic cylinders, already installed into large-scale machines, there is a general lack of reliable dynamic models. Also the suitable and feasible identification techniques, especially in frequency domain, yield limited. This paper proposes a minimal-modeling approach for determining the most relevant open-lo…
Anti-swing control of a hydraulic loader crane with a hanging load
2021
Abstract In this paper, anti-swing control for a hydraulic loader crane is presented. The difference between hydraulic and electric cranes are discussed to show the challenges associated with hydraulic actuation. The hanging load dynamics and relevant kinematics of the crane are derived to create the 2-DOF anti-swing controller. The anti-swing controller is added to the electro-hydraulic motion controller via feedforward. A dynamic simulation model of the crane is made, and the control system is evaluated in simulations with a path controller in actuator space. Simulation results show significant reduction in the load swing angle during motion. Experiments are carried out to verify the perf…
Identification and control design for path tracking of hydraulic loader crane
2017
The controlled operation of hydraulic machines with multiple degrees of freedom is challenging due to complex nonlinear dynamics of cylinder actuators, in addition to multibody dynamics like in the case of hydraulic manipulators. This paper addresses the system identification and control design for path tracking of a standard hydraulic loader crane. The kinematics of the crane is solved for operation in the vertical plane and generation of trajectories for the tool tip to be followed. A frequency response measurements and analysis have been done for dynamics modeling of both hydraulic cylinders actuating main boom and jib. The static dead-zone type input non-linearity has been identified an…
Datorikas fakultātes docētaju slodžu uzskaites sistēma
2018
Kvalifikācijas darbā tiek iekļauta programmatūras prasību specifikācija (PPS) un programmatūras projektējuma apraksts (PPA) Datorikas fakultātes docētāju slodžu uzskaites sistēmai. Sistēma tika izstrādāta izmantojot Oracle datubāzi un Oracle SQL Developer , Sqlplus kā arī SQL*Loader . Sistēmas mērķis ir atvieglot to kā tiek aprēķinātas pasniedzēju slodzes, pēc kurām arī nosaka, kāds ir konkrētā docētāja atalgojums atkarība no izdarītā darba. Šajā sistēmā ir iespējams arī izmantot meklētaju, lai atrastu informāciju par konkrētu docētāju, kādus kursus pasniedz, cik studentiem māca, cik stundas ir nostrādāts. Autentificētiem lietotājiem arī ir iespējams pievienot jaunus datus, vai nu tas būtu …
Development of 3D Anti-Swing Control for Hydraulic Knuckle Boom Crane
2021
In this paper, 3D anti-swing control for a hydraulic loader crane is presented. The difference between hydraulic and electric cranes are discussed to show the challenges associated with hydraulic actuation. The hanging load dynamics and relevant kinematics of the crane are derived to model the system and create the 3D anti-swing controller. The anti-swing controller generates a set of tool point velocities which are added to the electro-hydraulic motion controller via feedforward. A dynamic simulation model of the crane is made, and the control system is evaluated in simulations with a path controller in actuator space. Simulation results show significant reduction in the load swing angles …
Using input shaping and pressure feedback to suppress oscillations in slewing motion of lightweight flexible hydraulic crane
2015
This paper presents a method to actively reduce vibrations in the flexible mechanical structure of a hydraulically actuated vehicle loader crane. Based on information on the natural frequency and damping of a simplified model of the crane an input shaping scheme is set up to control the proportional valve leading to substantially reductions in oscillations. The method is compared and combined with a pressure feedback control of the proportional valve that actively suppresses transient variations in pressure. A full scale vehicle loader crane is used in the experimental verification of the method, and the motion of the tool point of the crane is measured by a high precision laser tracker. Th…
Considerations on oversized transportation in the UE(Community)
2017
The transportation problem is becoming increasingly complex at a national, European and global level. Achieving an efficient and safe transportation system with low environmental pollution, with a quick delivery is a requirement for any carrier in the 21 st century. When talking about oversized transport, the challenge is even greater. Making a low loader go through several European countries has proved to be more complicated than we expected, due to the lack of uniformity of laws in this field. This paper seeks to find these different regularities characteristics from one European country to another and to propose developing procedures leading to the design and implementation of cheaper an…
Clinical effectiveness and safety of a distraction-rotation knee brace for medial knee osteoarthritis
2015
Abstract Objective Evaluation of the clinical effectiveness and safety of a new custom-made valgus knee brace (OdrA) in medial knee osteoarthritis (OA) in terms of pain and secondary symptoms. Methods Open-label prospective study of patients with symptomatic medial knee OA with clinical evaluation at 6 and 52 weeks (W6, W52). We systematically assessed pain on a visual analog scale (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), spatio-temporal gait variables, use of nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesic-sparing effects of the brace and tolerance. Mean scores were compared at baseline, W6 and W52 and the effect size (ES) and 95% confidence intervals (95% CI…
Muzeja pamatkrājuma elektroniskais katalogs
2019
Kvalifikācijas darbā ir izstrādāts Latvijas Universitātes muzeja pamatkrājuma elektroniskais katalogs. Sākotnēji, muzeja darbinieki muzeja eksponenta uzskaiti veidoja excel formātā, kur bija apkopoti dati par priekšmetu autoriem, izmēriem, topogrāfijas novietojumiem utt.. Tomēr šie dokumenti bija tikai redzami muzeja darbiniekiem, un nebija saskarsmes ar lietotāju. Tādēļ tika nolemts, ka nepieciešams datus konvertēt uz jaunu datubāzi, kurai tiek veidota lietotāju saskarsme caur Latvijas Universitāti. Pēc sistēmu ievades, lietotāji varēs apskatīt kuri priekšmeti un kurā vietā no katra muzeja kataloga ir izlikti kā eksponenti, savukārt muzeja darbinieki ir vienīgie kuri varēs rediģēt vai piev…
From ship loader to port city. The case of Porto Empedocle (Da caricatore a città portuale. Il caso di Porto Empedocle)
2014
Porto Empedocle was, for many centuries, the port of the nearby city of Agrigento, imposing itself for exceptional locational qualities as maritime crossroads between all the seaports on the south coast of Sicily, albeit with ups and downs. Thanks to its strategic location, facing the north African coast and connections to the inner areas, the simple warehouse and provisioner became crucial for the economy of the island so as to be called the "most active warehouse and provisioner of the kingdom". Were performed a series of measures aimed at achieving real port facilities which would transform the original glade in functional landing place for boats of any size. Due its history, Porto Emped…