A closed-loop control system for heavy-duty industrial robots based on indoor infrared positioning technology was proposed to solve the problem of low positioning accuracy and unsatisfactory machining accuracy caused by insufficient stiffness of some heavy-duty industrial robots. The system consists of five parts: infrared emission diode, infrared irradiancy sensors, signal transmission and reception processing device, positioning service device, and heavy-duty robot. The positioning principle and method of the system were analyzed. The infrared emission diode is the most critical electronic component of the system. Due to the inability of ordinary infrared emission diodes to emit infrared rays with circumferential uniform intensity, luminous part of ordinary infrared emission diodes and packaging structure were redesigned to obtain an infrared emission diode which can emit infrared rays with circumferential uniform intensity. The simulation analysis of the light irradiancy intensity of the redesigned infrared emission diode proves that the structure can meet the design requirements. The proposed closed-loop control system for heavy-duty industrial robots can to some extent overcome the problems caused by insufficient stiffness without changing the existing robot structure, maintain the machining accuracy of the robot within an acceptable range, and provide a solution for the implementation of the next heavy-duty industrial robot system.
A heavy-duty industrial robot with a load of 3.5kn and a positioning accuracy of 0.05mm was combined with the end effector of friction stir welding and refitted into a robot friction stir welding system. In the friction stir welding machining test, it was found that although the structural strength of the robot met the use requirements, its stiffness under some working conditions didn’t meet the requirements, resulting in low positioning accuracy and unsatisfactory machining accuracy of the friction stir welding robot. To solve this problem, a closed-loop controlled heavy-duty friction stir welding robot system based on ultrasonic positioning technology was designed. The system was composed of dual ultrasonic transmitters, multiple ultrasonic receivers, positioning processor. Two ultrasonic transmitters with different transmission frequencies were arranged at two different positions of the end effector, and then two groups of receivers that could distinguish the ultrasonic frequency were used to receive the ultrasonic signal. The real-time coordinates of the two ultrasonic transmitters in the positioning space were calculated by the positioning system to determine the position and posture of the end effector. The end effector was controlled to track the predetermined trajectory in real time to realize the closed-loop control of the robot. Based on the three-point positioning principle, the relevant calculation and analysis were carried out, which proved the rationality and feasibility of the system in theory. The experimental results show that the positioning accuracy of the system is within 1mm and the posture error is within 0.01˚.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.