A Position-Based Explicit Force Control Strategy Based on Online Trajectory Prediction

4SPRR-SPR parallel robot is a novel closed-loop mechanism. The research of kinematics is the basis of real-time and robust robot control. This paper aims to proposing a method to address a surrogate model of forward kinematics for PMs (Parallel Mechanisms). Herein, the forward kinematics model is derived by training the VQTAM (Vector-Quantified Temporal Associative Memory) network, which originates from a SOM (Self-Organized Mapping). During the processes of training, testing and estimating this neural network, the priority K-means tree search algorithm is utilized, thus improving the training efficacy. Furthermore, LLR (Local Linear Regression), LWR (Local Weighted Linear Regression) and LLE (Local Linear Embedding) algorithms are respectively combined with VQTAM to get three improvement algorithms, aiming to further optimize the prediction accuracy of the networks. To speed up solving the least squared equation in the three algorithms, SVD (Singular Value Decomposition) is introduced. Finally, Data from inverse kinematics by geometric method is obtained, which is for constructing and validating the VQTAM neural network. Results show that the prediction effect of LLE algorithm is better than others, which could be a potential surrogate model to estimate the output of forward kinematics.

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“…The establishment of the mapping process is shown in Figure 4. The definitions of X in and X out are shown in equations (10) and (11).…”

Section: System Identification Of Non-linear Dynamical System Using Vmentioning

confidence: 99%

Kinematic of 4SPRR-SPR parallel robots based on VQTAM

Luo

Hou

et al. 2020

Advances in Mechanical Engineering

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“…The explicit force control selects the directions in which the end-effector position should be controlled and those directions in which the forces controlled by the end-effector are applied on some environment, for a given task. This type of control strategies has two feedback loops for separated, position, and force control and is referred to as hybrid force/position control [1,[21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

Section: Journal Of Roboticsmentioning

confidence: 99%

“…Recently, in [16] a double active observer control is proposed to control the desired interaction and motion compensation under contact with the heart, relying on robot force control techniques. In [34], a position-based force explicit control strategy based on online trajectory prediction, with proportional-integral-type control structure, is presented. In this work, the experimental results show that the proposed method has a good control effect on the contact force.…”

Section: Journal Of Roboticsmentioning

confidence: 99%

A Family of Hyperbolic-Type Explicit Force Regulators with Active Velocity Damping for Robot Manipulators

Reyes-Cortés

Chávez-Olivares

González-Galván

2018

Journal of Robotics

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This paper addresses the explicit force regulation problem for robot manipulators in interaction tasks. A new family of explicit force-control schemes is presented, which includes a term driven by a large class of saturated-type hyperbolic functions to handle the force error. Also, an active velocity damping term with the purpose of obtaining energy dissipation on the contact surface is incorporated plus compensation for gravity. In order to ensure asymptotic stability of the closed-loop system equilibrium point in Cartesian space, we propose a strict Lyapunov function. A force sensor placed at the end-effector of the robot manipulator is used in order to feed back the measure of the force error in the closed-loop, and an experimental comparison of the performanceL2-norm between 5 explicit force control schemes, which are the classical proportional-derivative (PD), arctangent, and square-root controls and two members of the proposed control family, on a two-degree-of-freedom, direct-drive robot manipulator, is presented.

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“…Xie et al [4], Huang et al [5], and Joshi et al [6] studied type synthesis for different types of lower-mobility PMs. Typical lower-mobility PMs such as 2-UPR-SPR PM [7] and 3-UPS-UP PM [8,9] have been used as position adjusters (R, P, U, S stand for revolute, prismatic, universal and spherical joints, respectively). To the best of our knowledge, researchers have mainly focused on studying the type synthesis of 5-DOF PMs [5,[10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Kinematics and workspace analysis of 4SPRR-SPR parallel robots

et al. 2021

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The 4SPRR-SPR parallel robot, which has considerable potential for application in the field of machining, is a novel closed-loop mechanism with a high rigid-weight ratio. Kinematics and workspace analyses of the 4SPRR-SPR parallel robot are key requirements for its application in machining. In this study, the inverse kinematics of the 4SPRR-SPR parallel robot is analyzed using a geometric method based on the mechanism arrangement of the robot. The forward kinematics model is derived by training the vector-quantified temporal associative memory (VQTAM) network, which originates from a self-organizing map (SOM). Furthermore, an improved algorithm is obtained by combining the locally linear embedding (LLE) and VQTAM methods. A boundary extraction algorithm for the workspace analysis of the parallel robot is proposed. The performance of the boundary extraction algorithm is analyzed and compared with that of a global search algorithm; the result indicates that the novel algorithm has the same computational accuracy in addition to higher efficiency. The workspace of the 4SPRR-SPR parallel robot is analyzed using the boundary extraction algorithm. Finally, the 3D model of the 4SPRR-SPR parallel robot is simulated using the ADAMS software to verify the reliability of the proposed algorithms. The simulation results demonstrate the effectiveness of the methods proposed in this study. In addition, the robot kinematics and workspace analysis methods described herein can be extended to other serial and parallel robots. This research provides a theoretical framework for trajectory planning of mechanisms, workspace optimization of robots, and robotic control.

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A Position-Based Explicit Force Control Strategy Based on Online Trajectory Prediction

Abstract: In the mirror milling process of large thin-walled parts, maintaining a constant supporting force is crucial for improving the workpiece local

Cited by 12 publications

References 16 publications

Kinematic of 4SPRR-SPR parallel robots based on VQTAM

Kinematic of 4SPRR-SPR parallel robots based on VQTAM

A Family of Hyperbolic-Type Explicit Force Regulators with Active Velocity Damping for Robot Manipulators

Kinematics and workspace analysis of 4SPRR-SPR parallel robots

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