Study on optic fiber sensor technology for pose warp in robot screw flexible assembly

摘要

Screw assembly takes certain proportion in assembly work, and to achieve automatic screw flexible assembly is a difficulty in automatic flexible assembly system. In view of special requirements in robot screw flexible assembly, the paper proposes a new optic fiber sensing structure which detects the orientation and position errors of screws. The paper proposes a novel multi-optic-fiber-sensor measurement and treatment method based on SSPA that works under photoelectric diode electrical charge storage style and has high detecting sensitivity. At the same time, the multi-route signals going through the same SSPA apparatus make the system have higher capability/price ratio. As the signals are serially sampled in an instant by the same apparatus (SSPA), the measured object's actual situation is reflected and the influent factors such as changes caused in different time by light path and measured object are eliminated. And the precision of the sensor is also increased. A new method by changing clock frequency of SSPA and controlling the output of light source power is proposed to enlarge SSPA's detecting range. Through the treatment method of partitioning the multi-output BP network into several single-output ones and the subsection of variables' value between input and output, the dynamic capability is improved consumedly; At the experimental platform based on the optic-fiber-sensing-technology the experiment successively accomplishes the initial screwing process of M8 screw and bolt with orientation warp of 0～10° and position error of 4～12mm. When the orientation warp is 9.24° and initial position error is 8.72mm, the time spent at initial screwing process is 20 seconds. If the pose warp is smaller, the time will be shorter.