Logistics Industry | Logistics sorting system

Author: DAHENG IMAGING Date: 2017-11-14

Industry: Logistics Industry

Project: Logistics sorting system

Background

During the whole supply chain, sorting is the most cumbersome work, which takes a long time and the sorting error rate will directly affect the work efficiency.

In the automated production line, there are multiple goods of the same type in each basket on the conveyor belt The goods are usually sorted, read barcode and recorded by manual operation, and then they are sent to the picking area.  Because the types of goods, the shapes and materials are different, a large amount of manpower are required for the sorting. It not only takes a long time and have a high sorting error rate, but also has a high labor cost, thus greatly slow down the delivery speed. DAHENG IMAGING's self-developed vision guided system, equipped with DAHENG IMAGING industrial camera, professional and reliable technical team, opens a new chapter in the application of 3D technology for machine vision inspection in logistics industry.

Challenge

1)  Currently on the market is mostly used a single camera to guide the robot picking, which can only get the object's 2D position, still there are many limitations on the placement of objects. But the cost of 3D cameras guiding robot picking system is very high.

2)  Spatial interference problem: Calibration of the spatial coordinate system between the camera and the robot in different fields of view is diverse.

Solution

The intelligent vision-guided system developed by DAHENG IMAGING can rapidly classify the objects and get the position of the objects. This system is composed of DAHENG IMAGING MERCURY digital camera, which equipped with a USB3.0 interface to transfer data to the PC controller for analysis and processing. A GigE interface is used to transfer the processed data to the robot to guide picking. This sorting system can be used not only for automatic sorting in the logistics industry, but also for various industrial applications such as positioning, inspection, measurement, etc. (as shown in figure 1).

Figure 1: Vision sorting system based on 3D vision

The logistics vision sorting system is built by DAHENG IMAGING MERCURY camera and a delta robot. This 3D vision inspection system mainly consists of 3D image acquisition module, 3D image processing module, image coordinates to robot coordinates module, hand-eye calibration module and robot control module, the flow chart is shown as Figure 2.

Figure 2: Components of robot vision-guided system

Procedure

1)  The 3D vision system is used to capture the high-speed moving goods baskets on the conveyor line and get the 2D and 3D information of the goods.

2)  Reconstruct the 3D geometric information (3D contour and position) of the object by Stereo vision method.

3)  After obtaining the 3D geometric information of the object, "3D image processing module" divides each piece of goods independently on the basis of its 3D features and derives the most suitable picking posture of the goods, so that the robot can pick the goods quickly and accurately.

4)  Using the "image coordinates to robot coordinates" module, the suitable picking position of the goods is converted into the coordinates, and the coordinate data is transmitted to the robot through the vision communication protocol, and the robot control module controls the robot to execute the picking action. As shown in Figure 3.

Figure 3: Robotic positioning and grasping

The image acquisition system is composed of two Mercury area scan cameras and a laser light source. The field of view (FOV) and measurement range (MR) cover the whole basket. The system uses the DAHENG IMAGING MER-U3 series cameras, which are compliant with the USB3 Vision standard. The host driver adopts a "zero-copy" mechanism, and the CPU occupancy is very low under the real time high bandwidth, which comparable to the 1394 bus.

Advantages

1)  Higher sorting speed. And with the features of fast, accurate and adaptable, it can reach a goal of 2,000 to 3,000 items per hour, which greatly improves the efficiency of logistics automation and satisfy the high demand even at the peak of orders.

2)  Upgrade the grasping position from 2D to 3D and reduce the cost.

3)  Breakthrough in coordinate calibration of 3D vision and robot grasping in terms of different fields of view. The technical team of DAHENG IMAGING has developed a set of calibration methods to tackle this problem, so that the installation position of vision system and robot is no longer restricted, which solves the difficulties of space obstacle in actual project construction.

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