Clearance effected accuracy and error sensitivity analysis: A new nonlinear equivalent method for spatial parallel robot

Dai, Yuanxing; Fu, Yanming; Li, Baichun; Wang, Xuezhi; Yu, Tianbiao; Wang, Wanshan

doi:10.1007/s12206-017-1044-x

Cited by 8 publications

(4 citation statements)

References 24 publications

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“…According to Table 3, the Type II singularity was expected to appear at 2.8 s. However, the proposed sensor-based procedure identified the Type II singularity at 2.4 s. |J D | verified that the proposed sensor-based procedure anticipated the Type II singularity (see Figure 12). This is because non-modelled effects, such as clearances in joints, generate regions with singularities in actual PKMs [34]. The degeneracy of the end-effector motion with non-sudden changes in actuator currents was observed again towards the end of TM4 (Figure 13).…”

Section: Resultsmentioning

confidence: 92%

Sensor-Based Identification of Singularities in Parallel Manipulators

Pulloquinga,

Ceccarelli,

Mata

et al. 2024

Actuators

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Singularities are configurations where the number of degrees of freedom of a robot changes instantaneously. In parallel manipulators, a singularity could reduce the mobility of the end-effector or produce uncontrolled motions of the mobile platform. Thus, a singularity is a critical problem for mechanical design and model-based control. This paper presents a general sensor-based method to identify singularities in the workspace of parallel manipulators with low computational cost. The proposed experimental method identifies a singularity by measuring sudden changes in the end-effector movements and huge increments in the forces applied by the actuators. This paper uses an inertial measurement unit and a 3D tracking system for measuring the end-effector movements, and current sensors for the forces exerted by the actuators. The proposed sensor-based identification of singularities is adjusted and implemented in three different robots to validate its effectiveness and feasibility for identifying singularities. The case studies are two prototypes for educational purposes—a five-bar mechanism and an L-CaPaMan parallel robot—and a four-degree-of-freedom robot for rehabilitation purposes. The tests showcase its potential as a practical solution for singularity identification in educational and industrial robots.

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Section: Resultsmentioning

confidence: 92%

Sensor-Based Identification of Singularities in Parallel Manipulators

Pulloquinga,

Ceccarelli,

Mata

et al. 2024

Actuators

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“…Generally, the singularities of a PR are analyzed without modeling manufacturing errors because of their random behavior. Dali et al, in [25], showed that the actual position of the mobile platform of a PR has errors caused by manufacturing errors in links and joints. Chen et al [26] model the position error due to joint clearances and input uncertainties in different joints of a planar PR.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of Type II singularities and assembly change points in a 3UPS+RPU parallel robot

Pulloquinga

Mata

Valera

et al. 2021

Mechanism and Machine Theory

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“…Taking the Pa-Quad parallel mechanism as an example, Sun et al 20 proposed the accuracy improvement strategy by geometric accuracy design and error compensation. Dai et al 21 adopted a nonlinear method for evaluating the pose error source. Kong et al 22 identified the kinematic parameters based on the modified DH kinematics model.…”

Section: Introductionmentioning

confidence: 99%

Accuracy analysis and synthesis of asymmetric parallel mechanism based on Sobol-QMC

Yue

Chen

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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Aiming at the aircraft composite skin grinding, a new three degree-of-freedom (DOF) parallel mechanism with asymmetrical structure (TAM) is proposed to replace manual grinding. The TAM is achieved by integrating one of active limbs into the passive limb while keeping the required DOF unchanged, which is divided into two closed-loop chains: telescopic rod and parallelogram. The inverse kinematics models of the two chains are established according to closed-loop vector method. Thus, the actuation and the constraint Jacobian matrix are obtained. Based on the perturbation principle, the error modeling of the TAM is built. Adopting the constraint Jacobian matrix, 15 uncompensated errors are distinguished from the error model. In order to improve the working accuracy of the TAM, accuracy analysis and synthesis are necessary for all the uncompensated errors. The mapping function reflects the influence of uncompensated errors on the pose accuracy. The global sensitivity evaluation indexes are established by mapping function. Since Sobol sequences are superior in uniformity and convergence, the Quasi-Monte Carlo method based on Sobol sequences (Sobol-QMC) is introduced for sensitivity analysis. Taking the minimum manufacturing and installation costs as the optimization target, the objective function of accuracy synthesis is constructed. Ultimately, the reasonable tolerance zone of each uncompensated error is calculated by genetic algorithm. Simulation is performed by Sobol-QMC to verify the rationality of the optimization. The results show the probability is above 97% where most pose errors are in [[Formula: see text], [Formula: see text]] within the workspace. Therefore, accuracy synthesis is correct and practical.

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Clearance effected accuracy and error sensitivity analysis: A new nonlinear equivalent method for spatial parallel robot

Cited by 8 publications

References 24 publications

Sensor-Based Identification of Singularities in Parallel Manipulators

Sensor-Based Identification of Singularities in Parallel Manipulators

Experimental analysis of Type II singularities and assembly change points in a 3UPS+RPU parallel robot

Accuracy analysis and synthesis of asymmetric parallel mechanism based on Sobol-QMC

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