Pneumatically Assisted Automatic Spinning Yarn Piecing Robot With Tension Control Method

Ring spinning is a critical process in yarn manufacturing, during which yarn breakage frequently occurs in actual production. To achieve yarn piecing after breakage, an automatic spinning yarn piecing robot which can complete the piecing operation precisely within 30 s is proposed. This article innovatively employs the asymmetric conical tubes to achieve yarn motion control and utilizes pneumatic differential nozzles for the positioning of the steel traveler. The structural parameters of the above two types of nozzles are optimized by refining the operating conditions. Meanwhile, the tension acting on the yarn is analyzed, and a tension control model is established for the drafting process. An online tuning method for the admittance control parameters based on tension prediction is proposed to achieve precise tension control of the yarn. Finally, a prototype of the robot is developed and the functions of the robot are thoroughly tested. The coordinated actions of the pneumatic nozzles and the robotic arm enable precise yarn leading and threading processes. During the drafting process, the proposed tension control method effectively reduces the tension fluctuations on the yarn. The robot can complete the piecing operation, achieving a success rate of 98% and exhibiting excellent automation and operational stability.