Calculation method of gravitational vector in robot coordinate system

Abstract

The invention relates to the field of dynamics computation of robots, and specifically relates to a calculation method of a gravitational vector in a robot coordinate system. The method specifically comprises the following steps: S1, positioning a marker; and marking in gravity direction; S2, affirming P1; S3, affirmingP2; S4, calculating unit vector; and S5, calculating the gravitational vector. According to the method, the gravitational vector direction is converted into a visible straight line through a fine rope hanging a heavy matter; coordinates of points on the straight line are measured through a robot treated as a position sensor, and the unit vector of the straight line is calculated based on the coordinates of the points; and finally, the gravitational vector can be calculated based on the unit vector direction of the straight line and local gravitational acceleration. Compared with a traditional method which depends on user given mounting type, the method has the advantages that the gravitational vector can be recognized at any mounting angle; the coordinates of two or a plurality of points are measured to recognize the gravitational vector; the operation is simple; and a movement model of which the accuracy is beyond that of a dynamic model is selected for recognizing the gravitational vector, so that the accuracy is improved.

Description

technical field [0001] The invention relates to the field of robot dynamics calculation, in particular to a calculation method of a gravity vector in a robot coordinate system. Background technique [0002] With the development of robotics, related functions based on dynamics such as collision detection, dragging and teaching have been widely used. In these applications, it is necessary to set the description of the gravity vector in the robot coordinate system. Whether the gravity vector is set accurately will have a great influence on the effect of these dynamic applications, so how to accurately measure the gravity vector is very important. [0003] In the existing related technologies, the following two schemes are usually used to determine the gravity vector: [0004] Option 1: Determined by the installation method selected by the user: when using the dynamics function, the user will select the installation method in the teach pendant according to the installation met...

AI Technical Summary

Problems solved by technology

The algorithm of this scheme is relatively complicated, requires accurate model parameters and establishes a dynamic model, and cannot be applied to robots without accurate dynamic model parameters

[0006] The determination of the direction of the gravity vector in Scheme 1 can only be determined by user input, and the gravity vector cannot be identified independently, while Scheme 2 establishes the mathematical relationship between the gravity vector and the torque of each axis, and then solves the gravity vector based on this relationship. The scheme algorithm is relatively complicated, and the identification accuracy depends on the accuracy of the model, but due to the existence of friction, etc., the dynamic model generally has a large error, so it is not practical

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