Mechanical arm kinematics MDH parameter calibration method based on self-adaptive gradient descent

Abstract

The invention discloses a mechanical arm kinematics MDH parameter calibration method based on self-adaptive gradient descent. A kinematics parameter model of the mechanical arm is established by utilizing the MDH parameters, and a reference coordinate transformation matrix between the tail end coordinate system of the mechanical arm and the basic coordinate system is obtained; the mechanical arm is controlled to move to a specified posture, all joint rotation angles controlled and set by the controller are recorded, actual coordinates of a mechanical arm tail end coordinate system relative to a basic coordinate system are obtained through measurement of a laser tracker, and an actual coordinate transformation matrix of the mechanical arm tail end coordinate system relative to the basic coordinate system is calculated; a target function which takes the MDH parameter as an independent variable and reflects the deviation between the actual pose and the theoretical pose of the tail end coordinate system of the mechanical arm is built; and the ideal MDH parameter is taken as an initial value, and optimizing is conducted by utilizing a self-adaptive gradient descent method to obtain an MDH parameter which enables the target function to take a minimum value, namely an actual MDH parameter. According to the method, the kinematics MDH parameters of the mechanical arm are calibrated, the defect that a traditional method is sensitive to sensor measurement errors is overcome, and the method is more stable and reliable.

Description

technical field [0001] The invention belongs to the field of kinematics error identification of a manipulator, and in particular relates to a MDH parameter calibration method for manipulator kinematics based on adaptive gradient descent. Background technique [0002] Based on the MDH (Modified Denavit-Hartenberg) parameter definition, the kinematics model of the manipulator can be obtained, which describes the correspondence between the MDH parameters of the manipulator joints and the pose of the end coordinate system in the base coordinate system. With the rapid development of intelligent manufacturing in the world, the demand for robotic arms is getting higher and higher, and the requirements for positioning accuracy of robotic arms are also getting higher and higher. The accuracy of the kinematic parameters of the robotic arm is the most important factor affecting the accurate positioning An important factor of control. [0003] During the manufacturing, assembly, and us...

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Problems solved by technology

[0006] In the above-mentioned MDH parameter calibration technology, the mapping relationship matrix J is usually a singular matrix, so the condition number of J is very large, and the measurement error disturbance δe p A small change of MDH parameters will produce a large error value δq, making the parameter identification process sensitive to external interference signals and affecting the accuracy of the calibration results

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