1. Research on hierarchical decoupling compensation method for positioning error of parallel industrial robot:

There are many factors that cause positioning errors of parallel industrial robots, and the coupling relationship is complex. A single calibration method cannot achieve high-precision error compensation. Relying on simple hierarchical and multi-level error compensation strategies will lead to redundant calibration of robot positioning errors, which cannot maximize the accuracy performance of industrial robots. Therefore, it is urgent to study how to scientifically hierarchically calibrate and decouple the mutual coupling degree of errors, so as to realize the hierarchical decoupling compensation of industrial robot positioning errors.

2. Research on high-precision compensation method for stiffness error of parallel industrial robot:

Compared with serial industrial robots, parallel industrial robots have better structural rigidity. Under the same load, the parallel robot is less affected by the load. However, when the load is large or the change is large, it will still cause a non-negligible positioning error. The joint stiffness error model of serial industrial robots cannot be directly used to calibrate parallel industrial robots. Therefore, how to realize the positioning error detection and compensation of parallel industrial robots under variable load conditions is one of the key technologies to promote its wide application in high-end manufacturing fields.

3. Research on high-precision compensation methods for position-sensitive errors of parallel industrial robots:

It is generally believed that the joint parameter error, geometric parameter error, flexibility error and other error factors of industrial robots have nothing to do with the joint position of the robot. However, the study found that the hysteresis error of the strut, the flexibility error caused by the robot's own weight, and the clearance of the kinematic pair all have a great correlation with the position of the strut of the robot. Therefore, how to realize reasonable modeling, high-precision identification and high-efficiency compensation for position-sensitive errors is also one of the key problems to be solved in robot calibration technology.