In the paper a fast computational routines for identification algorithms for recovering nonlinearities in Hammerstein systems based on orthogonal series expansions of functions are proposed. It is ascertained that bot...
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ISBN:
(纸本)9789898111999
In the paper a fast computational routines for identification algorithms for recovering nonlinearities in Hammerstein systems based on orthogonal series expansions of functions are proposed. It is ascertained that both, convergence conditions and convergence rates of the computational algorithms are the same as their much less computationaly attractive 'theoretic' counterparts. The generic computational algorithm is derived and illustrated by three examples based on standard orthogonal series on interval, viz. Fourier, Legendre, and Haar systems. The exemplary algorithms are presented in a detailed, ready-to-implement, form and examined by means of computer simulations.
This paper deals with multi-arms fruits picking in orchards. More specifically, the goal is to control the arms to approach the fruits position. To achieve this task a VPC strategy has been designed to take into accou...
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ISBN:
(纸本)9789897583803
This paper deals with multi-arms fruits picking in orchards. More specifically, the goal is to control the arms to approach the fruits position. To achieve this task a VPC strategy has been designed to take into account the dynamic of the environment as well as the various constraints inherent to the mechanical system, visual servoing manipulation and shared workspace. Our solution has been evaluated in simulation using on PR2 arms model. Different models of visual features prediction have been tested and the entire VPC strategy has been run on various cases. The obtained results show the interest and the efficiency of this strategy to perform a fruit picking task.
Compliant mechanisms have been used in several robotics applications, including locomotion and grasping. Variable stiffness joints are part of these compliant mechanisms and generally use one passive element per joint...
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ISBN:
(纸本)9798331517519;9798331517526
Compliant mechanisms have been used in several robotics applications, including locomotion and grasping. Variable stiffness joints are part of these compliant mechanisms and generally use one passive element per joint. This paper presents the design, model, and characterization of a Variable Stiffness Multi-joint Mechanism (VSMM) using a single carbon fibre rod as its passive element. The VSMM employs a variable lever mechanism, allowing the modulation of the joints' stiffness. We present an analytical model of the mechanism, providing insights into its mechanical behaviour and enabling the prediction of stiffness variations under different design parameters. Through experimental testing, the mechanism demonstrates a stiffness range of 0.19N/ mm to 0.27N/ mm, offering variable compliance that can change to suit specific task requirements.
Robotic systems are used within a great variety of medical disciplines. A handheld robot promises a number of advantages compared to conventional (medical) robots but this approach leads to strict specifications regar...
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ISBN:
(纸本)9789898111319
Robotic systems are used within a great variety of medical disciplines. A handheld robot promises a number of advantages compared to conventional (medical) robots but this approach leads to strict specifications regarding size, weight and dynamic properties. A new hybrid kinematics - the Epizactor - seems to be advantageous and is compared to two well-known parallel kinematics regarding the ratio of workspace and volume the number of kinematic elements, the cost of computation, the stiffness the effects of clearance, actuation (weight), and accuracy using a well-described industrial method for comparison. It becomes clear that the Epizactor has advantages concerning the ratio of workspace and volume, needs a smaller number of kinematic elements and fewer computations, and has less than half the mass than the parallel kinematics. Its accuracy, stiffness and the effects of clearance are comparable. The advantages of this new kinematic set-up lead to a first deployment within the field of medical robotics.
A three dimensional localisation algorithm for a swarm of underwater vehicles is presented. The proposed approach is grounded on an extended Kalman filter (EKF) scheme used to fuse some proprioceptive data such as the...
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ISBN:
(纸本)9789898565716
A three dimensional localisation algorithm for a swarm of underwater vehicles is presented. The proposed approach is grounded on an extended Kalman filter (EKF) scheme used to fuse some proprioceptive data such as the vessel's speed and some esteroceptive measurement such as the time of flight (TOF) sonar distance of the companion vessels. The results of several simulations are presented. Some considerations about the available underwater bandwidth and the communication needed by the approach are discussed.
Vectorization is a widely used technique in many areas, mainly in robotics and image processing. Applications in these domains frequently require both speed (for real-time operation) and accuracy (for maximal informat...
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ISBN:
(纸本)9789897581984
Vectorization is a widely used technique in many areas, mainly in robotics and image processing. Applications in these domains frequently require both speed (for real-time operation) and accuracy (for maximal information gain). This paper proposes an optimization for the high speed vectorization methods, which leads to nearly optimal results. The FTLS algorithm uses the total least squares method for fitting the lines into the point cloud and the presented augmentation for the refinement of the results, is based on a modified Nelder-Mead method. As shown on several experiments, this approach leads to better utilization of the information contained in the point cloud. As a result, the quality of approximation grows steadily with the number of points being vectorized, which was not achieved before. Performance costs are still comparable to the original algorithm, so the real-time operation is not endangered.
In this research, we focus on the 6D pose estimation of known objects from the RGB image. In contrast to state of the art methods, which are based on the end-to-end neural network training, we proposed a hybrid approa...
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ISBN:
(纸本)9789897583803
In this research, we focus on the 6D pose estimation of known objects from the RGB image. In contrast to state of the art methods, which are based on the end-to-end neural network training, we proposed a hybrid approach. We use separate deep neural networks to: detect the object on the image, estimate the center of the object, and estimate the translation and "in-place" rotation of the object. Then, we use geometrical relations on the image and the camera model to recover the full 6D object pose. As a result, we avoid the direct estimation of the object orientation defined in SO3 using a neural network. We propose the 4D-NET neural network to estimate translation and "in-place" rotation of the object. Finally, we show results on the images generated from the Pascal VOC and ShapeNet datasets.
Simulation frameworks are wide-spread in the range of robotics to test algorithms and analyze system behavior beforehand - which tremendously reduces effort and time needed for conducting experiments on the real machi...
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ISBN:
(纸本)9789898565716
Simulation frameworks are wide-spread in the range of robotics to test algorithms and analyze system behavior beforehand - which tremendously reduces effort and time needed for conducting experiments on the real machines. This paper addresses a component based framework for simulating a wall-climbing robot that uses negative pressure adhesion in combination with an omnidirectional drive system. Key aspect is the adhesion system which interacts with the environmental features such as surface characteristics (e. g. roughness) or defects. An elaborate thermodynamic model provides the basis for a realistic simulation of the airflow between the virtual environment and the vacuum chambers of the robot. These features facilitate the validation of closed-loop controllers and control algorithms offline and in realtime.
This paper presents the development of an integrated strawberry harvesting robotic system tested in lab conditions in order to contribute to the automation of strawberry harvesting. The developed system consists of th...
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ISBN:
(纸本)9789897583803
This paper presents the development of an integrated strawberry harvesting robotic system tested in lab conditions in order to contribute to the automation of strawberry harvesting. The developed system consists of three main subsystems;the vision system, the manipulator and the gripper. The procedure for the strawberry identification and localization based on vision is presented in detail. The performance of the robotic system is assessed by the results of experiments that take place in the lab and they are related to the recognition of occluded strawberries, the check of the strawberries for possible bruises after the grasping and the accuracy of detection of the strawberries' location. The results show that the developed vision algorithm recognizes correctly every single strawberry and has high accuracy in recognizing occluded strawberries in which the largest part of each of them is visible. A small localization error results in a correct grasp and cut without causing damage to the fruit.
Physical rehabilitation aims to improve the condition of people with any musculoskeletal disorder. Different assistive technologies have been developed to provide support to this process. In this context, human-machin...
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ISBN:
(纸本)9789897585227
Physical rehabilitation aims to improve the condition of people with any musculoskeletal disorder. Different assistive technologies have been developed to provide support to this process. In this context, human-machine interaction has progressively improved to avoid abrupt movements and vibrations, to obtain a more natural interaction, where control strategies play a key role. In this work, a control technique based on the combination of nonlinear adaptive theory with a hybrid impedance control applied to a 7-DoF upper limb assistance robotic device is proposed. Additionally, we include the stability analysis using Lyapunov functions. Then, we validate the strategies through simulations for one rehabilitation routine test. The articular and cartesian obtained results demonstrate the effectiveness of the control to follow trajectories. The control stabilizes the trajectories in 0.9 seconds even when the initial conditions start far from the desired trajectories, without producing vibrations or overshoots, which is the desired behavior in rehabilitation applications like the one we propose.
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