# Research of Flexible Assembly of Miniature Circuit Breakers Based on Robot Trajectory Optimization
## 2 Construction of MCB Flexible Assembly Platform
### Process of Robotic Flexible Assembly  
A flexible switch control method is proposed. An auxiliary adjustment rack for all parts is designed. The work platform that adjusts random postures of the parts to the specified postures is shown in Figure 3, including a six-axis robot, a flexible multi-gripper claw, an MCB assembly platform, a loading carrier, a positioning carrier, and an auxiliary adjustment rack.  
Figure 4 shows the designed flexible multi-gripper claw on the robot. Four grippers with different strokes (11-17 mm, 16-22 mm, 3-9 mm and 0-6 mm, respectively) are designed to match different sizes and assembly requirements of the parts. To effectively hold parts of different sizes and shapes, the ends of the grippers are in specified shapes. The width of the clamping position for the yoke and the magnetic system rack is 1 mm, and that for the big-U rod is 1.2 mm. The connections between the end effector, slider cylinder, and gripper cylinder are also designed. In an adjustment process, the robot automatically chooses a gripper whose stroke range matches the size of the part.  
Figure 1: Internal structure of an MCB.  
Figure 2: Models of the parts to be assembled.  
The auxiliary adjustment rack which fixes the parts in specified postures are shown in Figure 5.  
It is composed of a set of slots as transits to help the part posture adjustment.  
Based on the robot assembly platform and the corresponding mechanism shown in Figures 3-5, this paper proposes the following flexible assembly method and process of the MCB. Specifically, the arc extinguisher is adjusted by the gripper 1 and 2, the magnetic yoke is adjusted by gripper 3 and 4, the big-U rod is adjusted by gripper 4, and the magnetic system is adjusted by gripper 3 and 4, and the handle is coordinated by gripper 3 and 4. Taking the posture adjustment of the arc extinguisher as an example, the postures are categorized into three situations. The specified process that uses gripper 1 and 2 to adjust  
Figure 4: Robot flexible multi-gripper claw.  
Figure 5: Auxiliary adjustment rack for the parts.  
Figure 3: Posture adjustment platform.  
the arc extinguisher is shown in Figure 6a. In the case of posture 1, it is rotated around the Z axis by a certain angle by gripper 2, and then placed in the arc extinguisher slot on the positioning carrier. In the case of posture 2, it is clamped by gripper 1 and rotated counterclockwise around the Y-axis and clockwise around Z-axis, and then placed into the auxiliary adjustment rack. Finally, gripper 2 is applied to put it into the arc extinguisher slot. In the case of posture 3, it is clamped by the gripper 1, rotated clockwise around the Y-axis and counterclockwise around the Z-axis, and then placed into the auxiliary adjustment rack. Finally, gripper 2 is applied to put it in the arc extinguisher slot after rotating it around the Z axis.  
Figure 6b shows the schematic diagram of posture adjustment of the yoke, big-U rod, magnetic system, and handle. The postures are similarly adjusted as the arc extinguisher in Figure 6a, and finally all the parts are placed in the positioning carrier in specified postures, as shown in Figure 7.