Error Compensation Approach Research Articles

Sub-aperture algorithm for motion compensationimprovement inwide-beam SAR data processing

The effects of strong motion errors in wide-beam azimuth synthetic aperture radar (SAR) processing are analysed and discussed, using simulated data, as well as data collected by the airborne experimental SAR system of the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) (E-SAR). A new sub-aperture approach for residual motion error compensation in wide-beam azimuth processing is proposed.

Dynamic Modeling Based on Real-Time Deflection Measurement and Compensation Control for Flexible Multi-Link Manipulators

The problem of tip trajectory tracking control is considered in this paper for flexible multi-link manipulators. An integrated optical laser sensor system is utilized to measure the tip deformations of the flexible links. The Lagrangian assumed-mode method incorporating the measured linear displacements and angular deflections of flexible links is used to derive the dynamic model of the flexible manipulator. To reduce as far as possible the tip tracking/positioning errors caused by the link flexibility, an error compensation approach is proposed. The additional compensation amounts of joint variables are calculated kinematically in terms of the measured deformations, and are added to the nominal commands generated by the computed torque controller. The simulation results demonstrate the effectiveness of the proposed approach.

A Simple yet Effective Approach for Error Compensation of a Tripod-Based Parallel Kinematic Machine

This paper presents a simple yet effective approach for the error compensation of a tripod-based parallel kinematic machine. In this approach, the forward kinematics is formulated in such a way that the coordinate of the tool tip in z direction can be explicitly represented by the dimensional parameters and actuated variables. This enables one to implement the linear least square method to estimate the kinematic parameter errors. This approach has been successfully used for the error compensation of a prototype. The measurements of a test workpiece show that once the error in the z direction is properly compensated, the errors in x and y directions can be automatically compensated.

Optimal temperature variable selection by grouping approach for thermal error modeling and compensation

One of the difficult issues in a thermal error compensation scheme is to select appropriate temperature variables as well as to obtain accurate thermal error component models. In this research, an optimization method is presented to overcome this difficulty. The optimization objective function is formulated by a modified model adequacy criterion based on the Mallows' C p statistic. A new search method is developed for discrete search domains with non-directional or unknown-order variables. The search process includes correlation grouping, representative searching, group searching and variable searching. It not only ensures optimal results but also reduces computational time greatly. One modeling example is presented. The optimal model is found with a 0.982 R 2-value using four temperature variables selected from 46 candidates of temperature variables. The largest error residual is reduced down to 2.2 microns from 20.0 microns. The comparison of modeling results from the proposed approach and three other modeling methods is addressed as well.

A functional approach of error compensation in a two-dimensional measuring device with lower stiffness.

A functional approach of error compensation in a two-dimensional measuring device with lower stiffness.