An inertial parameter identification method of eliminating system damping effect for a six-degree-of-freedom parallel manipulator

Abstract

A new simple and effective inertial parameter identification method based on sinusoidal vibrations of a six-degree-of-freedom parallel manipulator is proposed. Compared with previously known identification algorithms, the advantages of the new approach are there is no need to design the excitation trajectory to consider the condition number of the observation matrix and the inertial matrix can be accurately defined regardless of the effect of viscous friction. In addition, the use of a sinusoidal exciting trajectory allows calculation of the velocities and accelerations from the measured position response. Simulations show that the new approach has acceptable tolerance of dry friction when using a simple coupling parameter modified formula. The experimental application to the hydraulically driven Stewart platform demonstrates the capability and efficiency of the proposed identification method.

Modeling and Analysis of a Multi-Degree-of-Freedom Micro-Vibration Simulator

“…Pedrammehr et al [16] produced the improved dynamic equations of the GSP, which took into account the rotational degree of the pods around the axial direction. Similar efforts can be found in [17][18][19][20]. Generally in the literature, many researches focused on the influence of the inertia forces, Coriolis forces, and the frictional forces on the dynamics control of the GSP.…”

A Parameter Identification Method for Stewart Manipulator Based on Wavelet Transform

“…The method based on Fourier transform is proposed by Tian et al [11] by solving the coefficient equations of Fourier transform. For identification of the inertial parameters, this method has high accuracy, and the identification process is simple and effective.…”

“…The manipulator has a total of six degrees of freedom, including three degrees of freedom of motion and three degrees of freedom of rotation around the axis. The equations of motion of Stewart manipulator are derived using Kane's method [11,19] and are written as: In order to reduce the independent variables and to identify the parameters easily, the movement of the platform is limited to a small range of motion; thus, the dynamic model of the Stewart manipulator can be expressed as: In order to reduce the independent variables and to identify the parameters easily, the movement of the platform is limited to a small range of motion; thus, the dynamic model of the Stewart manipulator can be expressed as:…”

“…For the Stewart manipulator, Koekebakker proposed a method to identify by extracting the first-order coefficients of Fourier transform after six degrees of freedom exciting respectively, but this method did not take the phase lag caused by viscous friction into consideration, which had a relatively big influence on the identification [10]. Tian et al improved the method above by solving the coefficient equations of Fourier transform [11], but it is important to note that this method can not accurately identify the viscous parameters influenced by Coulomb friction; at the same time, relative high-frequency motion is needed in this method. The identification method of structural parameters based on wavelet transform was widely used in the identification of time-varying or time-invariant structural dynamics because of its good identification accuracy and simple identification process [12][13][14].…”

“…The manipulator has a total of six degrees of freedom, including three degrees of freedom of motion and three degrees of freedom of rotation around the axis. The equations of motion of Stewart manipulator are derived using Kane's method [11,19] and are written as:…”