Linear System Identification and Vibration Control of End-Effector for Industrial Robots

Abstract

This paper presents the discrete state space mathematical model of the end-effector in industrial robots and designs the linear-quadratic-Gaussian controller, called LQG controller for short, to solve the low frequency vibration problem. Though simplifying the end-effector as the cantilever beam, this paper uses the subspace identification method to determine the output dynamic response data and establishes the state space model. Experimentally comparing the influences of different input excitation signals, Chirp sequences from 0 Hz to 100 Hz are used as the final estimation signal and the excitation signal. The LQG controller is designed and simulated to achieve the low frequency vibration suppression of the structure. The results show that the suppression system can effectively suppress the fundamental natural frequency and lower vibration of end-effector. The vibration suppression percentage is 95%, and the vibration amplitude is successfully reduced from ±20 μm to ±1 μm. The present work provides an effective method to suppress the low frequency vibration of the end-effector for industrial robots.

A suppress-excite approach for online trajectory generation of uncertain motion systems

“…The chirp or swept sinusoidal signals are widely used in applications like synthetic sounds, mechanical vibration [60], radar and system identification [61,62]. Consider the overall transfer function of the parallel connection of 𝑚 transfer functions given as (15) where 𝛾 𝑓 𝑖 ∈ R is the gain that reflects the importance of the excitation band associated with the frequency 𝜔 𝑠 𝑖 , and 𝜃 𝑠 𝑖 ∈ [−𝜋, 𝜋] is its associated shift angle.…”

Procedure Proposal for Minimising the Dynamic Error of Second-Order Sensors

“…We chose to focus on second-order sensors in this paper because a significant proportion of real sensors are defined by this dynamic order, such as vibration and pressure sensors [28][29][30][31][32], and the mechanical construction of a wide variety of other measurement instruments [33]. The proposed procedure can be applied in both the time and frequency domains [34][35][36], which are used in practical implementations of procedures intended for sensor modelling. The solutions proposed in this study consists of three main steps:…”

“…where f r denotes the resonant frequency [Hz] [35,36]. Equations ( 7) and ( 8) form the basis for applying the MC method in the frequency domain.…”

Vibration Isolation of a Surveillance System Equipped in a Drone with Mode Decoupling

“…A method to identify a nonlinear system [6] and proper model selection procedure was also suggested [7]. A vibration of the end-effector for industrial robots was recently identified through a linear system identification method; after that, a vibration was reduced with the linear quadratic-Gaussian controller [8]. Moreover, an active vibration isolation system was presented for vibration isolation of a surveillance system [9].…”