Ⅰ. Application scenarios of shelf identification

Why do we need to identify the shelf?

Because the material shelf is not always fixed in a certain position. AMR performs operations such as pulling or jacking up the shelf, which requires precise positions of the shelf. The map can accurately locate the AMR, but cannot locate the position of the shelf, so the operation of shelf identification is required to determine the position of the shelf.

Standard requirements on the material shelf:

1. The four legs of the material shelf need to form a rectangle;

2. The other parts of the material shelf must be in axisymmetrical form, including the limit hole that cooperates with the jacking mechanism, and the material shelf part supported on the material shelf leg;

3. The inner width of the material shelf must be greater than the maximum width of the robot by 20cm, and there is a 10cm redundant adjustment space for the material shelf on the left and right sides;

4. The height of the material shelf is determined according to the stroke of the jacking module;

Ⅱ. The identification method selected by SEER Intelligent

1. Identification by reflective sticker

Graphical representation: Commonly used 3M reflective stickers

Principle: Reflective stickers are commonly used high-strength reflective materials. The identification of reflective stickers mainly relies on the principle that the reflectivity of the reflective sticker received by laser is much higher than that of ordinary objects in the environment, so the specific location of the reflective stickers can be easily determined according to the reflectivity.

Simple renovation required to use reflective stickers:

1. Operation method:

Cut two small pieces of reflective stickers and stick them on the leg of the material shelf on the side where the AMR will be drilled.

2. Sticking requirements:

① The center of the reflective sticker and the scanning plane of the laser radar installed on the AMR should be aligned in height

② The inner side of the reflective sticker is flush with the inner side of the material shelf leg, as shown in the figure below:

Instructions of use parameter configuration:

Use Roboshop Pro software, click the [Identification File] tab to enter the configuration interface, select a [shelf] file, and configure the parameters of the shelf description file in the properties window on the right. As shown below:

width: After renovation, the outer width of the two shelf legs in the drilling direction. The width here refers to the outermost width of the two reflective stickers after renovation;

length: the outermost width of the two shelf legs perpendicular to the drilling direction;

leg_width: the width of the reflective sticker. If a standard 3M car reflective sticker is selected, it is 0.05 (meters);

In addition to these three configuration parameters, there are also a wealth of configuration interfaces, which are the same as those in the use shape identification, such as the depth of drilling (align_depth), identification and drilling in different directions (detect_direction), and the adjusted drilling offset considering the shelf center of gravity (rec_off_x, rec_off_y, rec_off_angle) and other parameters.

2. The shape identification:

Graphical representation of laser radar shape identification: the blue coordinate system in the figure is the AMR vehicle body coordinate system, the dotted square is the configurable laser radar identification area, and the dotted line in the square is the schematic diagram of the laser radar scan.

Principle：shape identification is conducted through laser point cloud, and there is no need to paste reflective stickers. When using laser radar shape identification, it is necessary to ensure that the leg of the material shelf to be recognized is within the identification range of the laser radar, and the identification area can be configured according to the on-site environment.

Requirements for the shape and material of the legs of the shelf:

1. The surface of the shelf legs is smooth and flat;

2. The shape of the legs of the material shelf is a regular cube;

3. The surface of the legs of the material shelf cannot be made of specular reflective materials, semi-transparent materials, and black materials.

Graphical representation: Typical and available shelf legs

Instructions of use parameter configuration:

Use Roboshop Pro software, click the [Identification File] tab to enter the configuration interface, select a [shelf] file, and configure the parameters of the shelf description file in the properties window on the right.

The five parameters should be configured as shown in the figure:

1. rightStandardLength: the length of the right leg of the material shelf;

2. rightVerticalLength: the width of the right leg of the material shelf;

3. leftVerticalLength: the width of the left leg of the material shelf;

4. leftStandardLength: the length of the left leg of the material shelf;

5. distance: the distance between the inner sides of the legs of the material shelf;

In addition, the angle between the length and width of the shelf leg is 90° by default, and it can also be configured additionally. To ensure the accuracy of identification, the length and width of the shelf leg should be greater than 6cm.

Ⅲ. Identification operation instructions

After completing the configuration of the above reflective sticker or shape identification, you only need to configure the identification model file in the attribute of the front point corresponding to the shelf point, that is, the shelf file, and then set the ObsExpansion in the line attribute to 0 to avoid the situation that the robot stalls during the process of drilling the material shelf. Next, configure the execution action:

1. If it is required to identify the position of the material shelf, and drill into the material shelf to jack it up, you need to check "Recognize" and click "Load";

2. If there is no need to identify the position of the material shelf, drill in an open-loop to a fixed position and jack it up, you don't need to check "Recognize", just click "Load";

3. If it is required to identify whether there is a shelf in the position, and place the shelf, you need to check "Recognize", and click "Unload". If there is a shelf occupied, an error will be reported; if identification is not required, and it is required to open the loop and place it, you don't need to check "Recognize", just click "Unload";

4. There are a few cases where you need to click "Wait". If you check "Recognize" and then click "Wait", the robot will recognize the position of the material shelf, drill into the bottom of the material shelf, and then end the task without moving and jacking module; if you don't check "Recognize", and click "Wait" directly, the robot will navigate to the workstation with a fixed path, and then end the task without jacking.

Then if we select the execution action when executing the path planning, AMR will automatically switch to the identification mode at this front point, and calculate the center position of the shelf according to the position of the recognized shelf leg and automatically generate the route to this position.

Ⅳ. Instructions of identification in different directions

For an omnidirectional car with laser radar installed at the front and rear, the front, rear, left and right sides of the car can be detected through configuration. The configuration is shown in the following figure:

Ⅴ. Other instructions

1. To reduce wrong identification, when using the laser to identify the material shelf, the distance between the center of the front two legs of the material shelf and the front identification point should be less than 2m, and the angle deviation between the line from the center point to the identified position laser and the car body is less than 10°, and the angle deviation between the angle of the shelf itself and the AMR during identification is less than 20°;

2. To use the laser point cloud shape identification function, you need to configure the parameter "method_type" to "by_legShape", and avoid blocking the shelf legs in the laser radar identification area;

3. When using the reflective sticker method, the parameter "method_type" needs to be configured as "by_reflector", and you should also ensure that the legs of the material shelf cannot be covered;

4. Reflective sticker identification: the accuracy of the x and y directions is higher than ±1cm, and the angle accuracy is higher than 1°;

5. Shape identification: The accuracy of the x and y directions is higher than ±1cm, and the angle accuracy is higher than 1°.