Market Application Background
In the complex surface dispensing process of various 3C consumer electronics products such as mobile phone frames, VR/AR bezels, irregular/curved screens, and smartwatches and bracelets, the commonly available Cartesian coordinate dispensing machines can no longer meet the requirements for precise dispensing operations on inclined, curved, or edge surfaces of workpieces that are obscured by other components. This results in the dispensing head being unable to reach the fixed processing area or failing to complete the dispensing task in one go, thus affecting the overall dispensing quality of the product.
To address the interference issue between the dispensing valve and the workpiece in complex surface dispensing paths, the dispensing valve must form a specific angle with the product surface to ensure it is perpendicular to the tangent of the dispensing path and maintains a constant relative linear velocity. Adapting to irregularly shaped workpieces requires multi-dimensional adjustments to the relative posture of the dispensing valve.
The five-axis linkage dispensing machine combines linear axes X, Y, and Z and rotary axes A and B to achieve spatial control of the dispensing valve reaching complex surface machining, and performs high-precision dispensing tasks, making it the best choice for products with complex dispensing paths.
Limitations of three-axis and four-axis dispensing machine solutions:
These types of dispensing machines move based on a Cartesian coordinate system, making them suitable for dispensing tasks on straight lines or slightly curved surfaces. They are not suitable for processing workpieces with complex shapes such as narrow cavities or inclined surfaces.
Flexibility and adaptability: During the dispensing process, the position and angle of the dispensing valve relative to the workpiece cannot be dynamically adjusted, so it is generally only suitable for processing tasks with basic shapes and geometries. However, its flexibility and adaptability are limited for workpieces with complex surfaces.
Accuracy and efficiency: When dealing with tasks requiring dispensing on multiple spatial curves or complex surfaces, multiple machines and multiple positioning and installation steps may be necessary. This not only increases production costs and processing steps but also reduces overall dispensing efficiency. Furthermore, multiple parameter settings and calibrations may result in a loss of dispensing accuracy.
Positive motion technology solutions:
In response to existing market demands, Zheng Motion Technology has developed a five-axis linkage dispensing solution based on the VPLC series machine vision motion control integrated machine, which is suitable for high-precision dispensing of various complex surface workpieces and various adhesives.
The solution employs the RTCP tool center point following technology algorithm, which can achieve tracking control of various spatial trajectories. It enables the dispensing valve or workpiece to tilt and adjust its angle while dispensing, and the dispensing trajectory path always remains consistent with the product's flipping posture. This ensures the continuity and smoothness of the dispensing process and significantly improves the accuracy, quality, and efficiency of dispensing on spatial curved surfaces.
The solution also reduces the dispensing process for complex-shaped workpieces. By centralizing multiple processes, it enables high-speed and high-precision dispensing, simplifies the production process, and better adapts to the dispensing production needs of complex-shaped workpieces.
01. Application of Machine Vision Motion Control Integrated Machine in Five-Axis Linkage Dispensing
Design of a five-axis linkage dispensing solution for positive motion
• 24DI: Connects to origin, limit, and height sensors, as well as switch signals, encoders, etc.
• 12DO: High-speed output port for connecting to the hard trigger input of industrial cameras and dispensing valves;
• EtherCAT interface: Connects to the EtherCAT bus driver to control the movement of other axes;
• 6-channel differential pulse output: Connects to a pulse driver to control the X, Y, Z, A, and C axes;
• 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 applications.
Motion control and machine vision implementation process
(1) Machine vision
The machine vision system is responsible for automatically detecting the dispensing position on the workpiece. The process includes image acquisition, visual positioning, and position coordinate output. The controller processes the acquired images and fits template features of the dispensing area contour. Based on the relative position of the glue dot center and the dispensing area contour, the system automatically calculates and compensates for the coordinate values of the dispensing head offset caused by the rotation axis, ensuring that the dispensing head accurately moves to the predetermined dispensing position.
(2) Motion control
The system features RTCP (Rotary Tool Center Point Control) to ensure that the dispensing head is always precisely aligned with a specific position on the workpiece during multi-axis linkage operation, maintaining a constant relative posture and angle even when the workpiece or tool itself is rotating.
During motion control, ensure the C-axis remains at zero during calibration. Calibrate the A-axis using the horizontal angle calibration of the mechanical platform, and then calibrate the rotation center. Manually teach the three-point coordinates and record the angles at different postures, then calculate and execute the linkage path.
When establishing the five-axis linkage commands for the forward motion robot, the mechanical structure parameters are configured first. After completing the motion point programming, the dispensing path is taught through the camera center or needle tip, and the spatial angles and attitudes are adjusted based on the XYZ three-axis points. At the same time, the height of the working area is measured by a laser height sensor, and the relative distance between the dispensing head and the surface of the working area is kept constant by means of Z-axis coordinate compensation.
Five-axis linkage dispensing process
Core advantages of the solution
• The RTCP tool center point following technology algorithm can achieve tracking control of various spatial trajectories;
• Features five-axis application camera calibration, probe compensation, and position acquisition in various orientations;
• Combining vision and motion control eliminates the need for an additional industrial PC, thus saving hardware costs and reducing installation space;
• Processing speed can be set in segments to ensure smooth dispensing for different adhesive types and processing requirements;
• Supports dual rotary stage horizontal calibration and offset calibration;
• Smooth control of small line segments ensures both accuracy and efficiency in interpolation trajectory.
• Features include pre-open/close glue control, position comparison triggering, and coordinate transformation of spatial trajectory, optimizing the glue dispensing process and reducing glue waste;
• It integrates a miniaturized configuration platform, which supports the development and programming of user-defined human-machine interfaces, improving user-friendliness and ease of operation.
Solution Hardware Configuration
02. VPLC532E Machine Vision and Motion Control All-in-One Machine
The VPLC series machine vision motion control all-in-one machine is an EtherCAT bus vision motion controller based on the Linux system. It can operate offline and has rich built-in vision and motion control functions, which greatly simplifies the configuration process of vision and motion control projects. The core data interaction is fast, which can significantly reduce time and cost investment.
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.
The VPLC532E machine vision motion control all-in-one machine supports up to 32 axes, 24+6 digital inputs, 12+6 digital outputs, 4 high-speed latch inputs, 4 high-speed PWM and PSO hardware outputs, and comes with 6 high-speed pulse axes + encoder feedback, with a speed of up to 10M.
03. Provides easy-to-use visual dispensing development and debugging software.
Zheng Motion Technology continuously deepens and expands the application of its VPLC series vision motion control all-in-one machines in the dispensing industry, providing users with easy-to-use vision dispensing development and debugging software. This software combines a visual interface with rich vision and motion control functions; with simple parameter settings, vision dispensing project programs can be built, significantly shortening project development cycles and reducing development costs.
Introduction to the Functionality of Visual Dispensing Development and Debugging Software
Fully functional
It supports dispensing trajectory dot, line, circle, arc, continuous line segment, array, pre-opening and closing of dispensing, manual teaching, camera teaching, and dispensing process functions.
Machine vision correction
The product can be placed at any position and angle, and the visual system will automatically recognize and complete the dispensing and spraying of adhesive.
User-friendly interface with comprehensive functions
The debugging and programming operations are simple and convenient, and support teaching and jogging motion on visual images.
