**5. Conclusions**

This chapter introduces a novel method for measuring 6DOF variations of the robotic arms end effector using regional surface area descriptors and variant ICP to monitor accurate positioning and orientation. Experimental test results confirmed that the proposed method can accurately position and detect three angular errors, namely pitch, yaw, and roll angle, without referencing any known artifact for system alignment. A comprehensive measurement uncertainty was also performed to identify possible measured sources. From the measurement results, it reveals that the 3D optical probe can achieve 60 μm measurement accuracy and 100 μm depth resolution within the entire measurement range of 100 mm. On the other hand, for the automatic detection of the position and orientation on the robot arm end-effector, the experimental results show that it achieves the positioning accuracy of 100 um in the X, Y, and Z positions within the entire measurement range. Most importantly, it was also verified that the angular detection accuracy can be kept within 0.01 degrees for the pitch, yaw, and roll angular motions. The developed method can be widely applied to precise 6DOF detection of arbitrary objects moving dynamically in 3D space. Its high-accuracy 6DOF monitoring with target-free 3D image registration capability is a significant technical breakthrough in automated optical inspection (AOI) and precision metrology in manufacturing.
