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Dynamic motion primitives (DMPs) is a motion planning method based on the concept of teaching a robot how to move based on human demonstration. To this end, DMPs use a machine learning framework that tunes stable non-linear differential equations according to data sets from demonstrated motions. Consequently, the numerical solution of these differential equations represent the desired motions. The purpose of this article is to present the steps to apply the DMPs framework and analyse its application for automating motions of forestry cranes. Our study considers an example of a forwarder crane that has been equipped with sensors to record motion data while performing standard work in the forest with expert operators. The objective of our motion planner is to automatically retract the logs back into the machine once the operator has grabbed them manually using joysticks. The results show that the final motion planner has the ability of reproducing the demonstrated action with above 95% accuracy. In addition, it has also the versatility to plan motions and perform similar action from other positions around the workspace, different than the ones used during the training stage. Thus, this initial study concludes that DMPs gives the means to develop a new generation of dynamic motion planners for forestry cranes that readily allow merging the operator’s experience in the development process.
Pedro La Hera; Daniel Ortiz Morales; Omar Mendoza-Trejo. A study case of Dynamic Motion Primitives as a motion planning method to automate the work of forestry cranes. Computers and Electronics in Agriculture 2021, 183, 106037 .
AMA StylePedro La Hera, Daniel Ortiz Morales, Omar Mendoza-Trejo. A study case of Dynamic Motion Primitives as a motion planning method to automate the work of forestry cranes. Computers and Electronics in Agriculture. 2021; 183 ():106037.
Chicago/Turabian StylePedro La Hera; Daniel Ortiz Morales; Omar Mendoza-Trejo. 2021. "A study case of Dynamic Motion Primitives as a motion planning method to automate the work of forestry cranes." Computers and Electronics in Agriculture 183, no. : 106037.
The rising throughput of log-yards imposes new constraints on existing equipment and increases the complexity of delivering an optimal and uninterrupted supply of pulpwood to pulp mills. To find ways of addressing these problems by reducing log cycle times, this work uses a discrete-event mathematics model to simulate operations at a log-yard and study the impact of three different log-yard inventory strategies and two alternative machine systems for log transportation between main log-yard and buffer storage. The yard’s existing inventory strategy of last load in and first out limits access to older logs at the main storage site. By allocating space for 89,000 m3 and 99,000 m3 of pulpwood at the buffer storage it is possible to keep the log cycle time at the main storage to a maximum of 12 and 6 months. Additionally, the use of an alternative log transportation machine system comprising a material handler with a trailer increased the work time capacity utilization relative to the yard’s current machine system of two shuttle trucks and a material handler for transporting logs between the main and buffer storage areas. Compared to the currently-used last in first out inventory strategy and purposely emptying the main storage area once or twice per year did reduce the total work time of both machine systems by 14% and 30%. Consequently, the volume delivered from the buffer to the log-yard decreased on average by 17% and 37% when emptying the main storage area once and twice per year. Even with reduced work time when emptying the main storage area, both machine systems could fulfil given work load for transporting logs from the buffer storage to the main log-yard without interrupting operations of the log-yard.
Kalvis Kons; Pedro La Hera; Dan Bergström. Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations. Forests 2020, 11, 373 .
AMA StyleKalvis Kons, Pedro La Hera, Dan Bergström. Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations. Forests. 2020; 11 (4):373.
Chicago/Turabian StyleKalvis Kons; Pedro La Hera; Dan Bergström. 2020. "Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations." Forests 11, no. 4: 373.
This article deals with the topic of modelling the log-yard of one of our industry partners. To this end, our framework is based on discrete-events modelling (DEM), as consequence that many stages of the process run as a sequence of events. The sequence starts when trucks, trains or ships arrive loaded with logs to the log-yard. A machine unloads these logs and accumulates them in different storage areas. Consequently, a machine transports logs from these areas to the pulp mill, thus finishing the process. As using probability density functions is the core concept of DEM, the necessary process data to build these PDFs have been partly provided by the company. Other necessary data have been acquired through time studies, and by defining operational requirements. The company data tell when trucks, trains, or ships arrive to the log-yard, and the amount of volume they carry. The objective is to develop the necessary formulations, model calibration techniques, and software, such that computer simulations reproduce the quantities observed in these data. To this end, this work suggests two alternatives to analyse the data itself. These two alternatives lead to two different models: (1) The first being a hybrid model, in the sense that it involves the events in the process, and the logic decisions taken by machine operators for handling the incoming load, and (2) the second containing only the main mathematical essence of the process. After running 100 simulations, both mathematical models show that the simulated values for input and output, in terms of transport units and their volume, differ only by less than 3% compared to company data. The first model has also shown the ability to replicate the decision making that a machine operator undergoes for driving the logs to the storage areas, and from there to the mill. Therefore, the framework adopted provides the necessary mathematical tools and data analysis to model the log-yard and obtain highly reliable results via simulations.
Kalvis Kons; Pedro La Hera; Dan Bergström. Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics. Forests 2020, 11, 155 .
AMA StyleKalvis Kons, Pedro La Hera, Dan Bergström. Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics. Forests. 2020; 11 (2):155.
Chicago/Turabian StyleKalvis Kons; Pedro La Hera; Dan Bergström. 2020. "Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics." Forests 11, no. 2: 155.
Performing work for extended periods of time while using the lowest amount of resources is an important aspect for productivity in many industries. In forestry, the productivity of a forwarder is seen as the volume of material it can extract to a roadside landing in a certain amount of time, where the process of loading and unloading logs represents a large part of the work. During this process, the esnergy consumed by the machine is directly related to the speed of the crane. Thus, increasing productivity implies increasing the operating velocity of cranes. But according to current design of forestry cranes, this conversely leads to an undesired increase in consumption of resources (e.g. fuel). A second method is to alter the machine’s design, such as rotating the log bunk. This article considers both methods through a simulation-based comparison aiming to evaluate the energy consumption of two crane-bunk systems when loading. The first simulation system considers a forestry crane with a fixed log bunk (forwarder-like crane). The second simulation system takes into account a forestry crane and a rotating log bunk (harwarder-like crane). The analysis presented considers the fundamental mathematics required to analyze the dynamics of forestry cranes and the principles required to plan energy-optimal motions. The simulation results show that energy savings of 43% to 61% can be obtained by determining energy-optimal motions and using a harwarder-like crane architecture.
Xiaowei Dong; Omar Mendoza-Trejo; Daniel Ortiz Morales; Ola Lindroos; Pedro La Hera. Simulation-based comparison between two crane-bunk systems for loading work when considering energy-optimal motion planning. International Journal of Forest Engineering 2019, 31, 70 -77.
AMA StyleXiaowei Dong, Omar Mendoza-Trejo, Daniel Ortiz Morales, Ola Lindroos, Pedro La Hera. Simulation-based comparison between two crane-bunk systems for loading work when considering energy-optimal motion planning. International Journal of Forest Engineering. 2019; 31 (1):70-77.
Chicago/Turabian StyleXiaowei Dong; Omar Mendoza-Trejo; Daniel Ortiz Morales; Ola Lindroos; Pedro La Hera. 2019. "Simulation-based comparison between two crane-bunk systems for loading work when considering energy-optimal motion planning." International Journal of Forest Engineering 31, no. 1: 70-77.
Forestry machines have the power to efficiently move very heavy loads, but they are not very smart at communicating information, especially information regarding motion. Understanding how a system produces motion is one of the main stepping stones towards the world of automation. However, to acquire motion data requires sensor hardware that is not largely available in forestry machines today. As a result, at the moment there is no motion data analysis for forestry machines. Therefore, the objective of this article is to present this data, and discuss how we can use such data in regards to technology development. To this end, we have equipped a commercial forestry machine with state-of-the-art sensors and a data acquisition unit. Our aim is to understand what possibilities exist for automation, when we analyze how machine operators control forestry cranes. Among our objectives is to show how motion data can: a) give a better comprehension of the way forestry operators control cranes, b) be useful to analyze crane motion patterns, and c) show additional information that can be estimated via mathematical algorithms. The topics we cover only touch the surface of future applications, where sensor data analysis will be able to team up with other technologies to improve operator’s work, including automation, decision making, motion optimization, and operators’ training, just to mention some.
Pedro Xavier Miranda La Hera; Daniel Ortiz Morales. What Do We Observe When We Equip a Forestry Crane with Motion Sensors? Croatian journal of forest engineering 2019, 40, 259 -280.
AMA StylePedro Xavier Miranda La Hera, Daniel Ortiz Morales. What Do We Observe When We Equip a Forestry Crane with Motion Sensors? Croatian journal of forest engineering. 2019; 40 (2):259-280.
Chicago/Turabian StylePedro Xavier Miranda La Hera; Daniel Ortiz Morales. 2019. "What Do We Observe When We Equip a Forestry Crane with Motion Sensors?" Croatian journal of forest engineering 40, no. 2: 259-280.
Ola Lindroos; Omar Mendoza-Trejo; Pedro Xavier Miranda La Hera; Daniel Ortiz Morales; Sweden Cranab. Advances in using robots in forestry operations. Managing soil health for sustainable agriculture Volume 1 2019, 233 -260.
AMA StyleOla Lindroos, Omar Mendoza-Trejo, Pedro Xavier Miranda La Hera, Daniel Ortiz Morales, Sweden Cranab. Advances in using robots in forestry operations. Managing soil health for sustainable agriculture Volume 1. 2019; ():233-260.
Chicago/Turabian StyleOla Lindroos; Omar Mendoza-Trejo; Pedro Xavier Miranda La Hera; Daniel Ortiz Morales; Sweden Cranab. 2019. "Advances in using robots in forestry operations." Managing soil health for sustainable agriculture Volume 1 , no. : 233-260.
Model-based methods are used in industry for prototyping concepts based on mathematical models. With our forest industry partners, we have established a model-based workflow for rapid development of motion control systems for forestry cranes. Applying this working method, we can verify control algorithms, both theoretically and practically. This paper is an example of this workflow and presents four topics related to the application of nonlinear control theory. The first topic presents the system of differential equations describing the motion dynamics. The second topic presents nonlinear control laws formulated according to sliding mode control theory. The third topic presents a procedure for model calibration and control tuning that are a prerequisite to realize experimental tests. The fourth topic presents the results of tests performed on an experimental crane specifically equipped for these tasks. Results of these studies show the advantages and disadvantages of these control algorithms, and they highlight their performance in terms of robustness and smoothness.
Pedro Xavier Miranda La Hera; Daniel Ortíz Morales. Model-Based Development of Control Systems for Forestry Cranes. Journal of Control Science and Engineering 2015, 2015, 1 -15.
AMA StylePedro Xavier Miranda La Hera, Daniel Ortíz Morales. Model-Based Development of Control Systems for Forestry Cranes. Journal of Control Science and Engineering. 2015; 2015 ():1-15.
Chicago/Turabian StylePedro Xavier Miranda La Hera; Daniel Ortíz Morales. 2015. "Model-Based Development of Control Systems for Forestry Cranes." Journal of Control Science and Engineering 2015, no. : 1-15.
In this work we present an interactive video conferencing system specifically designed for enhancing the experience of video teleconferencing for a pilot user. We have used an Embodied Telepresence System (ETS) which was previously designed to enhance the experience of video teleconferencing for the collaborators. In this work we have deployed an ETS in a novel scenario to improve the experience of pilot user during distance communication. The ETS is used to adjust the view of the pilot user at the distance location (e.g. distance located conference/meeting). The velocity profile control for the ETS is developed which is implicitly controlled by the head of the pilot user. The experiment was conducted to test whether the view adjustment capability of an ETS increases the collaboration experience of video conferencing for the pilot user or not. The user study was conducted in which participants (pilot users) performed interaction using ETS and with traditional computer based video conferencing tool. Overall, the user study suggests the effectiveness of our approach and hence results in enhancing the experience of video conferencing for the pilot user.
M.S.L. Khan; Shafiq Ur Rehman; Pedro Xavier Miranda La Hera; Feng Liu; Haibo Li. A pilot user's prospective in mobile robotic telepresence system. Signal and Information Processing Association Annual Summit and Conference (APSIPA), 2014 Asia-Pacific 2014, 1 -4.
AMA StyleM.S.L. Khan, Shafiq Ur Rehman, Pedro Xavier Miranda La Hera, Feng Liu, Haibo Li. A pilot user's prospective in mobile robotic telepresence system. Signal and Information Processing Association Annual Summit and Conference (APSIPA), 2014 Asia-Pacific. 2014; ():1-4.
Chicago/Turabian StyleM.S.L. Khan; Shafiq Ur Rehman; Pedro Xavier Miranda La Hera; Feng Liu; Haibo Li. 2014. "A pilot user's prospective in mobile robotic telepresence system." Signal and Information Processing Association Annual Summit and Conference (APSIPA), 2014 Asia-Pacific , no. : 1-4.
We propose a novel method to analyze how human operators use hydraulic manipulators of heavy-duty equipment. The approach is novel in the sense that it applies knowledge of motion planning and optimization techniques used in robotics. As an example, we consider the case of operating a forestry crane. To that end, we use motion data that has been recorded during standard operation with the help of sensors and a data acquisition unit. The data backs up the notion that operators work by performing repeatable patterns observed in the trajectories of the manipulator's joints. We show how this nominal behavior is computed, and consequently, this allows us to present the following: 1) an analytical procedure to analyze motions, 2) how to represent the “performance” of the operator in a 2-D plot, 3) an example of how to use this information to suggest customized control settings, and 4) some complementary ideas needed for improving efficiency through automation.
Daniel Ortiz Morales; Pedro Xavier Miranda La Hera; Simon Westerberg; Leonid B. Freidovich; Anton S. Shiriaev. Path-Constrained Motion Analysis: An Algorithm to Understand Human Performance on Hydraulic Manipulators. IEEE Transactions on Human-Machine Systems 2014, 45, 187 -199.
AMA StyleDaniel Ortiz Morales, Pedro Xavier Miranda La Hera, Simon Westerberg, Leonid B. Freidovich, Anton S. Shiriaev. Path-Constrained Motion Analysis: An Algorithm to Understand Human Performance on Hydraulic Manipulators. IEEE Transactions on Human-Machine Systems. 2014; 45 (2):187-199.
Chicago/Turabian StyleDaniel Ortiz Morales; Pedro Xavier Miranda La Hera; Simon Westerberg; Leonid B. Freidovich; Anton S. Shiriaev. 2014. "Path-Constrained Motion Analysis: An Algorithm to Understand Human Performance on Hydraulic Manipulators." IEEE Transactions on Human-Machine Systems 45, no. 2: 187-199.
Working with forestry machines requires a great deal of training to be sufficiently skilled to operate forestry cranes. In view of this, it would be desirable within the forestry industry to introduce automated motions, such as those seen in robotic arms, to shorten the training time and make the work of the operator easier. Motivated by this fact, we have developed two experimental platforms for testing control systems and motion‐planning algorithms in real time. They correspond to a laboratory setup and a commercial version of a hydraulic manipulator used in forwarder machines. The aim of this article is to present the results of this development by providing an overview of our trajectory‐planning algorithm and motion‐control method, with a subsequent view of the experimental results. For motion control, we design feedback controllers that are able to track reference trajectories based on sensor measurements. Likewise, we provide arguments to design controllers in an open‐loop for machines that lack sensing devices. Relying on the tracking efficiency of these controllers, we design time‐efficient reference trajectories of motions that correspond to logging tasks. To demonstrate performance, we provide an overview of extensive testing done on these machines.
Daniel Ortiz Morales; Simon Westerberg; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid Freidovich; Anton S. Shiriaev. Increasing the Level of Automation in the Forestry Logging Process with Crane Trajectory Planning and Control. Journal of Field Robotics 2014, 31, 343 -363.
AMA StyleDaniel Ortiz Morales, Simon Westerberg, Pedro Xavier Miranda La Hera, Uwe Mettin, Leonid Freidovich, Anton S. Shiriaev. Increasing the Level of Automation in the Forestry Logging Process with Crane Trajectory Planning and Control. Journal of Field Robotics. 2014; 31 (3):343-363.
Chicago/Turabian StyleDaniel Ortiz Morales; Simon Westerberg; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid Freidovich; Anton S. Shiriaev. 2014. "Increasing the Level of Automation in the Forestry Logging Process with Crane Trajectory Planning and Control." Journal of Field Robotics 31, no. 3: 343-363.
Model-based design is a standard framework widely adopted in modern industry. It is used for designing multi-domain engineering solutions based on computer-aided simulation technology. Currently, this approach is also being considered as a tentative method for designing modern heavy-duty machine technology. Under this motivation, our aim is to present how modelling techniques can be used for simulating dynamics of forestry machines. To this end, we consider a forestry crane, and propose mathematical models and calibration techniques, such that model-based methods can subsequently be applied. The complexity of the machine is represented by first principle laws, in which the mechanical system is modelled by Euler-Lagrange formulations, and the hydraulic system is modelled by principles of fluid dynamics. The calibration algorithms are performed by statistical algorithms based on linear and non-linear least-squares methods. The results of simulation show a significant correspondence between the simulated and observed variables, validating our procedures.
Pedro Xavier Miranda La Hera; Daniel Ortíz Morales. Non-linear dynamics modelling description for simulating the behaviour of forestry cranes. International Journal of Modelling, Identification and Control 2014, 21, 125 .
AMA StylePedro Xavier Miranda La Hera, Daniel Ortíz Morales. Non-linear dynamics modelling description for simulating the behaviour of forestry cranes. International Journal of Modelling, Identification and Control. 2014; 21 (2):125.
Chicago/Turabian StylePedro Xavier Miranda La Hera; Daniel Ortíz Morales. 2014. "Non-linear dynamics modelling description for simulating the behaviour of forestry cranes." International Journal of Modelling, Identification and Control 21, no. 2: 125.
We analyze the problem of dynamic non-prehensile manipulation by considering the example of the butterfly robot. Our main objective is to study the problem of stabilizing periodic motions, which resemble some form of juggling acrobatics. To this end, we approach the problem by considering the framework of virtual holonomic constraints. Under this basis, we provide an analytical and systematic solution to the problems of trajectory planning and design of feedback controllers to guarantee orbital exponential stability. Results are presented in the form of simulation tests.
Daniel Ortíz Morales; Pedro Xavier Miranda La Hera; Shafiq Ur Rehman; Saif Ur Rehman. Generating periodic motions for the butterfly robot. 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems 2013, 2527 -2532.
AMA StyleDaniel Ortíz Morales, Pedro Xavier Miranda La Hera, Shafiq Ur Rehman, Saif Ur Rehman. Generating periodic motions for the butterfly robot. 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems. 2013; ():2527-2532.
Chicago/Turabian StyleDaniel Ortíz Morales; Pedro Xavier Miranda La Hera; Shafiq Ur Rehman; Saif Ur Rehman. 2013. "Generating periodic motions for the butterfly robot." 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems , no. : 2527-2532.
We consider a benchmark example of a three-link planar biped walker with torso, which is actuated in between the legs. The torso is thought to be kept upright by two identical torsional springs. The mathematical model reflects a three-degree-of-freedom mechanical system with impulse effects, which describe the impacts of the swing leg with the ground, and the aim is to induce stable limit-cycle walking on level ground. The main contribution is a novel systematic trajectory planning procedure for solving the problem of gait synthesis. The key idea is to find a system of ordinary differential equations for the functions describing a synchronization pattern for the time evolution of the generalized coordinates along a periodic motion. These functions, which are known as virtual holonomic constraints, are also used to compute an impulsive linear system that approximates the time evolution of the subset of coordinates that are transverse to the orbit of the continuous part of the periodic solution. This auxiliary system, which is known as transverse linearization, is used to design a nonlinear exponentially orbitally stabilizing feedback controller. The performance of the closed-loop system and its robustness with respect to various perturbations and uncertainties are illustrated via numerical simulations.
Pedro X. Miranda La Hera; Anton S. Shiriaev; Leonid B. Freidovich; Uwe Mettin; Sergey V. Gusev. Stable Walking Gaits for a Three-Link Planar Biped Robot With One Actuator. IEEE Transactions on Robotics 2013, 29, 589 -601.
AMA StylePedro X. Miranda La Hera, Anton S. Shiriaev, Leonid B. Freidovich, Uwe Mettin, Sergey V. Gusev. Stable Walking Gaits for a Three-Link Planar Biped Robot With One Actuator. IEEE Transactions on Robotics. 2013; 29 (3):589-601.
Chicago/Turabian StylePedro X. Miranda La Hera; Anton S. Shiriaev; Leonid B. Freidovich; Uwe Mettin; Sergey V. Gusev. 2013. "Stable Walking Gaits for a Three-Link Planar Biped Robot With One Actuator." IEEE Transactions on Robotics 29, no. 3: 589-601.
We present results of modeling dynamics of a forestry manipulator, in which we consider its mechanics, as well as its hydraulic actuation system. The mathematical model of its mechanics is formulated by Euler-Lagrange equations, for which the addition of friction forces is straightforward. Dynamics of the hydraulic system is modeled upon first principle laws, which concern flow through orifices and fluid compressibility. These models lead to a set of equations with various unknown parameters, which are related to the inertias, masses, location of center of masses, friction forces, and valve coefficients. The numerical values of these parameters are estimated by the use of least-square methods, which is made feasible by transforming the models into linear representations. The results of simulation tests show a significant correspondence between measured and estimated variables, validating our modeling and identification approach.
Pedro Xavier Miranda La Hera; Bilal Ur Rehman; Daniel Ortiz Morales. Electro-hydraulically actuated forestry manipulator: Modeling and Identification. 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems 2012, 3399 -3404.
AMA StylePedro Xavier Miranda La Hera, Bilal Ur Rehman, Daniel Ortiz Morales. Electro-hydraulically actuated forestry manipulator: Modeling and Identification. 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems. 2012; ():3399-3404.
Chicago/Turabian StylePedro Xavier Miranda La Hera; Bilal Ur Rehman; Daniel Ortiz Morales. 2012. "Electro-hydraulically actuated forestry manipulator: Modeling and Identification." 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems , no. : 3399-3404.
We consider the example of a three-link planar biped walker with two passive links. The main objective is to design symmetric periodic gaits in flat ground, that can be exponentially stabilized by feedback control. To this end, we apply recent advances in nonlinear control, to propose a systematic procedure to the problems of gait synthesis and control design. The core of the method lays on a nontrivial coordinate transformation, in order to approach the problem in a state-dependent form. For gait synthesis, such procedure allows a reduction of the search space, with the feasibility of considering energetic performance for optimization. For control design, this allows to apply concepts of transverse linearization, to design a nonlinear feedback control law, which performance is studied by numerical simulations.
Daniel Ortíz Morales; Pedro X. La Hera. Design of energy efficient walking gaits for a three-link planar biped walker with two unactuated degrees of freedom. 2012 IEEE International Conference on Robotics and Automation 2012, 148 -153.
AMA StyleDaniel Ortíz Morales, Pedro X. La Hera. Design of energy efficient walking gaits for a three-link planar biped walker with two unactuated degrees of freedom. 2012 IEEE International Conference on Robotics and Automation. 2012; ():148-153.
Chicago/Turabian StyleDaniel Ortíz Morales; Pedro X. La Hera. 2012. "Design of energy efficient walking gaits for a three-link planar biped walker with two unactuated degrees of freedom." 2012 IEEE International Conference on Robotics and Automation , no. : 148-153.
A short term goal in the forest industry is semi-automation of existing machines for the tasks of logging and harvesting. One way to assist drivers is to provide a set of predefined trajectories that can be used repeatedly in the process. In recent years much effort has been directed to the design of control strategies and task planning as part of this solution. However, commercialization of such automatic schemes requires the installation of various sensing devices, computers and most of all a redesign of the machine itself, which is currently undesired by manufacturers. Here we present an approach of implementing predefined trajectories in an open-loop fashion, which avoids the complexity of sensor and computer integration. The experimental results are carried out on a commercial hydraulic crane to demonstrate that this solution is feasible in practice.
Daniel Ortiz Morales; Simon Westerberg; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid Freidovich; Anton Shiriaev. Open-loop control experiments on driver assistance for crane forestry machines. 2011 IEEE International Conference on Robotics and Automation 2011, 1797 -1802.
AMA StyleDaniel Ortiz Morales, Simon Westerberg, Pedro Xavier Miranda La Hera, Uwe Mettin, Leonid Freidovich, Anton Shiriaev. Open-loop control experiments on driver assistance for crane forestry machines. 2011 IEEE International Conference on Robotics and Automation. 2011; ():1797-1802.
Chicago/Turabian StyleDaniel Ortiz Morales; Simon Westerberg; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid Freidovich; Anton Shiriaev. 2011. "Open-loop control experiments on driver assistance for crane forestry machines." 2011 IEEE International Conference on Robotics and Automation , no. : 1797-1802.
In the forest industry, trees are logged and harvested by human-operated hydraulic manipulators. Eventually, these tasks are expected to be automated with optimal performance. However, with todays technology the main problem is implementation. While prototypes may have rich sensing information, real cranes lack certain sensing devices, such as encoders for position sensing. Automating these machines requires unconventional solutions. In this paper, we consider the motion planning problem, which involves a redesign of optimal trajectories, so that open loop control strategies can be applied using feed-forward control signals whenever sensing information is not available.
Daniel Ortíz Morales; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid B. Freidovich; Anton S. Shiriaev; Simon Westerberg. Steps in trajectory planning and controller design for a hydraulically driven crane with limited sensing. 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems 2010, 3836 -3841.
AMA StyleDaniel Ortíz Morales, Pedro Xavier Miranda La Hera, Uwe Mettin, Leonid B. Freidovich, Anton S. Shiriaev, Simon Westerberg. Steps in trajectory planning and controller design for a hydraulically driven crane with limited sensing. 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems. 2010; ():3836-3841.
Chicago/Turabian StyleDaniel Ortíz Morales; Pedro Xavier Miranda La Hera; Uwe Mettin; Leonid B. Freidovich; Anton S. Shiriaev; Simon Westerberg. 2010. "Steps in trajectory planning and controller design for a hydraulically driven crane with limited sensing." 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems , no. : 3836-3841.
The planar motion to traverse from point to point with a ballbot is discussed. Our aim is to propose an analytical method to plan motions that can be robustly executed by feedback control. The approach is based on defining geometric virtual relations among the generalized coordinates. These relations form the basis of a reparametrization of the system dynamics for motion planning, and an introduction of coordinates transverse to the desired trajectories useful for controller design. Results of numerical simulation are presented to illustrate the performance and robustness of the closed-loop system.
Pedro Xavier Miranda La Hera; Leonid Freidovich; Anton Shiriaev; Uwe Mettin. Traversing from point-to-point along a straight line with a ballbot. IFAC Proceedings Volumes 2010, 43, 125 -130.
AMA StylePedro Xavier Miranda La Hera, Leonid Freidovich, Anton Shiriaev, Uwe Mettin. Traversing from point-to-point along a straight line with a ballbot. IFAC Proceedings Volumes. 2010; 43 (14):125-130.
Chicago/Turabian StylePedro Xavier Miranda La Hera; Leonid Freidovich; Anton Shiriaev; Uwe Mettin. 2010. "Traversing from point-to-point along a straight line with a ballbot." IFAC Proceedings Volumes 43, no. 14: 125-130.
We consider a 3-link planar walker with two legs and an upper body. An actuator is introduced between the legs, and the torso is kept upright by torsional springs. The model is a 3-DOF impulsive mechanical system, and the aim is to induce stable limit-cycle walking in level ground. To solve the problem, the ideas of the virtual holonomic constraints approach are explored, used and extended. The contribution is a novel systematic motion planning procedure for solving the problem of gait synthesis, which is challenging for non-feedback linearizable mechanical systems with two or more passive degrees of freedom. For a preplanned gait we compute an impulsive linear system that approximates dynamics transversal to the periodic solution. This linear system is used for the design of a stabilizing feedback controller. Results of numerical simulations are presented to illustrate the performance of the closed loop system.
Pedro X. La Hera; Anton S. Shiriaev; Leonid B. Freidovich; Uwe Mettin. Gait synthesis for a three-link planar biped walker with one actuator. 2010 IEEE International Conference on Robotics and Automation 2010, 1715 -1720.
AMA StylePedro X. La Hera, Anton S. Shiriaev, Leonid B. Freidovich, Uwe Mettin. Gait synthesis for a three-link planar biped walker with one actuator. 2010 IEEE International Conference on Robotics and Automation. 2010; ():1715-1720.
Chicago/Turabian StylePedro X. La Hera; Anton S. Shiriaev; Leonid B. Freidovich; Uwe Mettin. 2010. "Gait synthesis for a three-link planar biped walker with one actuator." 2010 IEEE International Conference on Robotics and Automation , no. : 1715-1720.
Pedro X. La Hera; Leonid B. Freidovich; Anton S. Shiriaev; Uwe Mettin. New approach for swinging up the Furuta pendulum: Theory and experiments. Mechatronics 2009, 19, 1240 -1250.
AMA StylePedro X. La Hera, Leonid B. Freidovich, Anton S. Shiriaev, Uwe Mettin. New approach for swinging up the Furuta pendulum: Theory and experiments. Mechatronics. 2009; 19 (8):1240-1250.
Chicago/Turabian StylePedro X. La Hera; Leonid B. Freidovich; Anton S. Shiriaev; Uwe Mettin. 2009. "New approach for swinging up the Furuta pendulum: Theory and experiments." Mechatronics 19, no. 8: 1240-1250.