This paper presents a new family of fully-parallel robots producing motions of the Schoenflies displacements subgroup (three translations and one rotation about a given axis in world coordinates) for high-speed handli...
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This paper presents a new family of fully-parallel robots producing motions of the Schoenflies displacements subgroup (three translations and one rotation about a given axis in world coordinates) for high-speed handling and machining. First, the structure's ability to provide this four-degrees-of-freedom motion is presented. Then, two of its possible designs are analyzed: the symmetrical and the asymmetrical one. Constructive designs are then presented. Some of the prototype's preliminary control results are given to prove the H4 robot's efficiency.
In this paper we present a particular architecture of parallel robots which has six-degrees-of-freedom (6-DOF) with only three limbs. The particular properties of the geometric and kinematic models with respect to tha...
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In this paper we present a particular architecture of parallel robots which has six-degrees-of-freedom (6-DOF) with only three limbs. The particular properties of the geometric and kinematic models with respect to that of a classical parallel robot are presented. We show that inverse problems have an analytical solution. However, to solve the direct problems, an efficient numerical procedure which needs to inverse only a 3 x 3 passive Jacobian matrix is proposed. In a second step, dynamic equations are derived using the Lagrangian formalism where the joint variables are passive and active joint coordinates. Based on the geometrical properties of the robot, the equations of motion are derived in terms of only nine coordinates related by three kinematic constraints instead of 18 joint coordinates. The computational cost of the dynamic model obtained is reduced by using a minimum set of base inertial parameters.
This paper presents an approach for the optimal design of a 2-DOF translational pick-and-place parallel robot. By taking account of the normalized inertial and centrifugal/Coriolis torques of a single actuated joint, ...
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This paper presents an approach for the optimal design of a 2-DOF translational pick-and-place parallel robot. By taking account of the normalized inertial and centrifugal/Coriolis torques of a single actuated joint, two global dynamic performance indices are proposed for minimization. The pressure angles within a limb and between two limbs are considered as the kinematic constraints to prevent direct and indirect singularities. These considerations together form a multi-objective optimization problem that can then be solved by the modified goal attainment method. A numerical example is discussed. A number of robots designed by this approach have been integrated into production lines for carton packing in the pharmaceutical industry. (C) 2013 Elsevier Ltd. All rights reserved.
Cancer represents one of the main causes of the death. Huge efforts have been made by the scientific community to provide better cancer treatment solutions. An innovative option is the brachytherapy (BT), a local radi...
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Cancer represents one of the main causes of the death. Huge efforts have been made by the scientific community to provide better cancer treatment solutions. An innovative option is the brachytherapy (BT), a local radiation technique for cancer treatment, which enables the delivery of high doses of radiation inside the tumors. BT usage is limited by the insufficient accuracy of the radioactive seeds placement. In order to eliminate these limitations, the authors propose an innovative modular structure which would enable the precise positioning of the BT needles in any part of the patient body. The paper presents the kinematic modeling of the new 5-DOF robotic structure. The workspace analysis and the singularities are studied and the dexterous workspace for a given insertion point inside the patient is also shown. Finally, some numerical simulations of different BT needle trajectories are included. (C) 2014 Elsevier Ltd. All rights reserved.
In this paper, analytic singularity analysis of a 4-DOF parallel robot H4 is addressed. Since a parallel manipulator consisting of several serial chains has complex singularities in the workspace, the determination of...
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In this paper, analytic singularity analysis of a 4-DOF parallel robot H4 is addressed. Since a parallel manipulator consisting of several serial chains has complex singularities in the workspace, the determination of singular configurations is very important in design, trajectory planning, and control. The classical method to determine singular configurations is to find the determinant of the Jacobian matrix. However, the Jacobian matrix of a parallel manipulator is complex in general and thus it is not easy to find the determinant of the Jacobian matrix. Therefore, we focus on the analytic singularity analysis of a 4-DOF parallel robot H4 using Jacobian deficiencies. A subset of the whole singularities and the intuitively predictable ones are only derived using Jacobian matrix deficiency. Three type singularities, i.e., overmobility, undermobility and combined singularities, have been presented.
Based on a novel six-degree-of-freedom (DOF) parallel manipulator mechanism, the forward and inverse kinematics have been worked out. This paper addresses the kinematics accuracy problem of the proposed new parallel r...
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Based on a novel six-degree-of-freedom (DOF) parallel manipulator mechanism, the forward and inverse kinematics have been worked out. This paper addresses the kinematics accuracy problem of the proposed new parallel robot with three legs (TLPM) due to the location of the U joint errors, clearance and driving errors. According to the generalized kinematic mapping of motions in the workspace, the end-effector's exact output error bound for a standard deviation of the components can have a great influence on the pose (position and orientation) error. The stochastic results are presented;for considering both the location errors clearance and driving in the total simultaneous effect of the errors, the superposition principle is not suitable when any of the errors is considerably larger than the last two errors. The accuracy is intensively studied, a laser tracker is applied to calibrate the errors. The models can be built into the controller and used to compensate for the location of the U joint errors, clearance and driving errors. Experimental results show that the robot accuracy is improved and demonstrated the effectiveness of the proposed method. (C) 2016 Elsevier Ltd. All rights reserved.
The trajectory tracking control of parallel robots is challenging due to their complicated dynamics and kinematics. This paper proposes a position -based visual servoing (PBVS) approach for a 6-Revolute-SphericalSpher...
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The trajectory tracking control of parallel robots is challenging due to their complicated dynamics and kinematics. This paper proposes a position -based visual servoing (PBVS) approach for a 6-Revolute-SphericalSpherical (6-RSS) parallel robot using adaptive sliding mode control in Cartesian space. A photogrammetry sensor C -Track 780 in the eye -to -hand configuration is adopted to measure the real-time pose of the robot end -effector, which can avoid the calculation of robot forward kinematics and provide more flexibility for controller design. An adaptive Kalman filter is utilized to deal with uncertain noises in visual measurements to increase the pose estimation accuracy. A sliding mode controller with strong robustness is designed to cope with system uncertainties, and a radial basis function (RBF) neural network is incorporated to realize the auto -tuning of the control gains, which make the robot effectively track different trajectories with time -varying conditions in real applications. Based on Lyapunov theorem, the stability analysis of the controller has been done. Experiments have been conducted to validate the effectiveness of the proposed strategy and illustrate the of the controller.
This paper is devoted to improving the synchronization and robustness performance of a parallel robot used for automobile electro-coating conveying via a novel synchronous robust sliding mode control (SMC). A sliding ...
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This paper is devoted to improving the synchronization and robustness performance of a parallel robot used for automobile electro-coating conveying via a novel synchronous robust sliding mode control (SMC). A sliding surface is designed based on a composite error, which is composed of the tracking error of each joint and the synchronization errors among the joints. By incorporating a nonlinear disturbance observer into the finite-time SMC based on the composite error, the synchronous robust SMC of the parallel robot is realized. The finite-time Lyapunov stability of the sliding variable and the asymptotic convergence of the tracking error and synchronization error have been proved theoretically. The lumped disturbance in the system is estimated by the proposed scheme, and restriction on the change rate of the lumped disturbance has been relaxed. Due to the feedforward compensation with the disturbance estimation value, the switching gain of SMC required is merely larger than the upper bound of the disturbance estimation error, rather than the upper bound of the disturbance, resulting in chattering attenuation. Finally, the numerical simulation and experiment on the prototype system of the parallel robot are implemented to validate the effectiveness of the synchronous robust SMC.
By taking a 2-DOF high-speed translational parallel manipulator as an object of study, this paper presents an approach that enables the servomotor parameters of parallel robots for pick-and-place operations to be esti...
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By taking a 2-DOF high-speed translational parallel manipulator as an object of study, this paper presents an approach that enables the servomotor parameters of parallel robots for pick-and-place operations to be estimated in an effective manner using the singular value decomposition. These parameters include the moment of inertia, speed, torque, and power of the motor required for producing the specified velocity and acceleration of the end effector An example is given to determine these parameters of a device for the rechargeable battery quality inspection.
This paper presents a novel mobile parallel robot, which is able to carry welding and machining processes from inside the international thermonuclear experimental reactor (ITER) vacuum vessel (VV). The kinematics desi...
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This paper presents a novel mobile parallel robot, which is able to carry welding and machining processes from inside the international thermonuclear experimental reactor (ITER) vacuum vessel (VV). The kinematics design of the robot has been optimized for ITER access. To improve the accuracy of the parallel robot, the errors caused by the stiffness and manufacture process have to be compensated or limited to a minimum value. In this paper kinematics errors and stiffness modeling are given. The simulation results are presented. (C) 2008 Elsevier B.V. All rights reserved.
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