Market Application Background
Busbar welding is a mid-stage processing technology for photovoltaic solar panels. Its preceding process is string welding, in which multiple solder strips are welded in parallel on the surfaces of multiple solar cells to form a battery string. The multiple strings of cells are then arranged and transported to the busbar welding worktable, where machine vision is used to perform overall panel positioning and correction operations to ensure welding accuracy.
Subsequently, these battery strings are interconnected by welding strips (busbars). In this step, welding torches are used to weld at the extended ends of the battery strings on both sides to achieve current collection between the battery strings and form a complete solar cell module.
Finally, these components will be transferred to the next process for lamination, frame mounting, junction box mounting, and other encapsulation processes, ultimately forming a durable, safe, and easy-to-install complete solar panel.
Problems with manual bus soldering:
Traditional manual busbar soldering solutions often face problems such as low production efficiency, unstable yield, large fluctuations in soldering quality, and limited flexibility. Ultimately, these not only affect product performance and reliability but also increase production costs and restrict the expansion of production scale.
Positive motion technology solutions:
In response to this market demand, Zheng Motion has developed a battery cell busbar soldering solution based on the VPLC711 vision motion control all-in-one machine combined with a SCARA robot and machine vision.
It can solve the string welding needs of photovoltaic solar panels with different angles and specifications, and achieve a significant improvement in production efficiency and precision. At the same time, it reduces the scrap rate to only 12%, significantly speeds up data processing, and improves the flexibility and automation level of the production line.
Furthermore, our solutions effectively reduce energy consumption by lowering scrap rates, contributing to environmental and sustainable development goals. Leveraging our highly integrated hardware and user-friendly RTFuse robotic system platform, customers enjoy a rapid return on investment, truly achieving efficient and environmentally friendly smart manufacturing.
01. Application of VPLC711-based robot system in photovoltaic busbar welding
Schematic diagram of a robot system based on VPLC711 in photovoltaic busbar welding.
Pain points of traditional busbar soldering solutions
Traditional solutions include components such as robot arm drive control, PLC, vision industrial computer, display, and touch screen. These solutions suffer from high hardware costs, long development cycles, low functional integration, low hardware-software integration, and unsatisfactory data interaction speeds.
Positive motion busbar welding solution design
●20DI: Connects to origin, limit, and other sensors, as well as switch signals, encoders, etc.
●20DO: Connects to a vacuum chuck; the high-speed output port connects to the hard trigger input of an industrial camera.
●EtherCAT Interface: Connects to the EtherCAT bus driver to control the movement of the SCRAR robot, the strip drawing axis, the welding axis, and other axes;
● 4-channel single-ended pulse output: connects to a stepper/pulse driver to control the soldering tape reel and conveyor belt;
●RS232 communication interface: Connected to the light source controller;
●EtherNET interface: Gigabit Ethernet port, for connecting area scan cameras that support the Gige protocol to achieve visual positioning and correction applications.
VPLC711 Machine Vision and Motion Control All-in-One Machine
The VPLC711 is a high-performance machine vision EtherCAT motion controller based on the x86 platform and Windows operating system. It can operate offline and supports a wide range of vision and motion control functions, greatly simplifying the configuration process for vision and motion control projects.
It also incorporates the MotionRT7 real-time motion control kernel, forming an open IPC-type real-time soft controller/soft PLC, providing users with a flexible and integrated motion control + vision solution.
The VPLC series machine vision motion control integrated machine is easy to install and remove, occupies little space, and can be seamlessly integrated with other control unit components (such as servo drives, sensors, encoders, control valves, etc.) to provide a complete end-to-end vision motion control solution.
●Optional 6-64 axis motion control (pulse + EtherCAT bus);
● Built-in real-time kernel MotionRT7, supporting third-party vision software;
● Onboard 20 general purpose inputs (10 of which are high-speed inputs), 20 high-speed outputs;
● Multi-core parallel computing enables efficient processing of core tasks in automated equipment such as motion control and machine vision;
● Open IPC form factor real-time soft controller/soft PLC, which can be flexibly integrated with motion control + vision integrated solution.
Solution Hardware Configuration
Motion control and machine vision implementation process
Machine vision
In the automated welding process of photovoltaic busbar welding, the machine vision system first performs coarse positioning through template matching, then uses double-line measurement to determine the corner position of the cell, and calculates the midpoint to achieve precise positioning, with accuracy meeting customer requirements.
The SCARA robot arm corrects its deviation based on the offset provided by the machine vision system, making it easier for the battery string to reach the processing area. The special long welding head presses precisely on the preset welding points at the ends of the battery string on both sides, completing a high-speed and high-precision welding operation.
Top camera substrate visual positioning
Motion control
The SCARA robotic arm operates along a pre-planned path, enabling point-to-point motion control. Throughout the process, the control system adjusts the joint speeds of the robotic arm to ensure it reaches the target position on time along the predetermined trajectory.
Once the material reaches the loading point, the robotic arm picks up the material and moves it to the vision inspection position. The system then performs coordinate offset calculations, enabling the SCARA robotic arm to dynamically adjust the position of the battery string in real time to complete the busbar welding on one side. After welding, the robotic arm transfers the product to a transfer platform for flipping, and then performs coordinate offset calculations again to complete the welding on the other side. Finally, the complete solar cell module is moved to the unloading area.
System Action Flow
1. Robotic arm material handling:
The robotic arm removes the product from the incoming conveyor belt, moves it to the vision imaging point, performs visual measurement and positioning, and then sends it to the welding position.
2. The feeding motor delivers the welding strip:
The feeding motor delivers the welding strip to the cutting position near the welding strip clamping cylinder and clamps the welding strip.
3. Start the flux pump:
Turn on the flux pump and simultaneously pull the solder strip motor to the preset length, then stop the flux pump.
4. Press and cut the welding strip:
The clamping cylinder clamps the welding strip, the vacuum is turned on, the welding strip is sucked up, and then the cutting cylinder cuts the welding strip.
5. Welding ribbon feeding:
The welding strip motor moves the welding strip to the welding start position, and the SCARA robot delivers the product into the welding position.
6. Visual positioning and correction:
The battery substrate is located using a vision system, and the welding positions are corrected.
7. Perform welding:
The welding head descends to the designated position, the welding process begins, welding is completed, the welding head returns to the position to be welded, and the robot arm removes the product.
8. Product transshipment:
After the robotic arm rotates 180 degrees, it disconnects the vacuum and places the product into the transfer platform. After returning to 0 degrees, it retrieves the product.
9. Repeat the welding process once:
After moving to the visual imaging point and performing visual positioning correction, the device is sent to the welding position, and steps 2 to 7 are repeated to complete the welding operation on the other side.
10. Product cutting:
After welding is completed, the robotic arm removes the product and places it on the unloading platform to prepare for the next round of welding operations.
Advantages of the solution
● Integrated control system: A single controller integrates machine vision, motion control, IO control, and robotic arm control, significantly saving equipment costs, shortening the development cycle, and simplifying installation and wiring.
● Built-in MotionRT7 real-time motion control kernel: Data interaction within the kernel, instruction call speed can reach microsecond level, which can greatly improve processing efficiency.
● Wide support for various robot types: Supports 30+ robot algorithm models, including SCARA, Delta, 6-joint, palletizing, etc., making robot control more open and flexible.
● Visual flying shot function: By outputting PSO through hardware position comparison, visual flying shot can be realized, improving the instantaneous triggering speed and accuracy of the vision system.
● Smooth motion control: Employs continuous S-curve acceleration/SS-curve acceleration technology to ensure a smoother motion control process.
● Unified API function interface: Compatible with various PC host computer high-level language development, simplifying the system integration and application development process for engineers.
02. Provides an easy-to-use visual RTFuse robot system platform.
RTFuse Robot System is a system-level software designed for the robotic arm market, supporting various mainstream robotic arm types such as Scana, Delta, six-joint, assisted, and Cartesian coordinate systems.
The software integrates functions such as visual motion control, IO logic control, communication interaction, and machine vision. Users can perform purely graphical programming on the teach pendant using the rich tools within the system, easily achieving one-stop programming development for Chinese teaching without writing code.
RTFuse Robotics System Platform Product Advantages
Low technical threshold
The drag-and-drop Chinese configuration system programming is easy for application engineers to learn after simple training. It executes project control processes from top to bottom, with manual teaching of robot arm positions.
The system is highly open
It supports multi-threaded control, and in addition to controlling the robotic arm, it can also control other auxiliary axes, IO logic control, communication interaction, etc., all of which can be accomplished by a single controller.
Strong integration of software and hardware
It integrates EtherCAT bus, pulse hybrid control, machine vision, and motion control, combining hardware and software for easy equipment debugging and troubleshooting.
Low labor costs for businesses
One person can debug the motion control, vision, and IO logic control of the equipment, solving problems such as the loss of engineering personnel and high labor costs.
