Model Overview

Open the model.

open_system('simulateWarehouseRobotInGazebo.slx')

The model can be divided into the following elements:

Schedule

The robot performs the task of going between the charging station, the loading station, and the unloading station as guided by theScheduler.

Sense

The current robot pose, the wheel speeds, and the range sensor readings are read from the simulated environment in Gazebo. The figure below is the expanded view of theRead From Gazebo Sensorssubsystem.

Control

The controller generates control commands for following the waypoints using thePure Pursuitblock. If the range sensor on the robot detects an obstacle within theavoidCollisionDistancethreshold, the robot stops. Also, the robot stops when gets near enough to the goal.

Actuate

Based on the generated control commands, thePioneer Wheel Controlsubsystem generates a torque value for each wheel.The torque is applied as anApplyJointTorquecommand.

Setup

Warehouse Facility

Load the example map file,map, which is a matrix of logical values indicating occupied space in the warehouse. Invert this matrix to indicate free space, and make abinaryOccupancyMapobject. Specify a resolution of 100 cells per meter.

The map is based off of thewarehouseExtensions.worldfile, which was made using the Building Editor on the same scaling factor as mentioned below. A.pngfile for the map can be made using thecollision_map_creator_plugin插件生成映射矩阵。The details on how to install the plugin can be found atCollision Map Creator Plugin.

mapScalingFactor = 100; loadgazeboWarehouseMap.matmaplogicalMap = ~map; map = binaryOccupancyMap(logicalMap,mapScalingFactor); show(map)

Assign thexy-locations of the charging station, sorting station, and the unloading location near shelves in the warehouse. The values chosen are based on the simlated world in Gazebo.

chargingStn = [12,5]; loadingStn = [24,5]; unloadingStn = [15,24];

Show the various locations on the map.

holdon; text(chargingStn(1), chargingStn(2), 1,'Charging'); plotTransforms([chargingStn, 0], [1 0 0 0]) text(loadingStn(1), loadingStn(2), 1,'Sorting Station'); plotTransforms([loadingStn, 0], [1 0 0 0]) text(unloadingStn(1), unloadingStn(2), 1,'Unloading Station'); plotTransforms([unloadingStn, 0], [1 0 0 0]) holdoff;

Range Sensor

TheRead Lidar Scanblock in theSensingsection is used to read the range values from the simulated range sensor. ThewarehouseExtensions.worldfile contains the details of the various models and actors (warehouse workers) in the scene. Because <actor>tags are static links with only visual meshes, the sensor type of the range sensor isgpu_ray.

Additionally, the range sensor uses 640 range, but the default is 128. This requires modification of the buses used in the in theRead Lidar Scanblock. Load theexampleHelperWarehouseRobotWithGazeboBuses.matfile to get a modified bus withGazebo_SL_Bus_gazebo_msgs_LaserScan.rangeset to 640. The modified buses were saved to a.matfile using the Bus Editor.

loadexampleHelperWarehouseRobotWithGazeboBuses.mat

Collision Avoidance

The actors in the world are walking a predefined trajectory. The robot makes use of a range sensor to check for obstacles within a range of 2.0 m (avoidCollisionDistance)with range angles from[-pi/10, pi/10]Upon a non-zero reading within that range and view, the robot stops and only resumes after the range is clear. The "Stop Robot On Sensing Obstacles" function block incorporates this logic.

While running the simulation, the停止lamp turns green when the robot senses that it is good to proceed. If it has stopped the lamp turns red.

avoidCollisionDistance = 2;

Simulate

To simulate the scenario, set up the connection to Gazebo.

First, run the Gazebo Simulator. In the virtual machine, click theGazebo Warehouse Roboticon. If the Gazebo simulator fails to open, you may need to reinstall the plugin. SeeInstall Gazebo PluginManuallyinPerform Co-Simulation between Simulink and Gazebo.

In Simulink, open theGazebo Pacerblock and clickConfigure Gazebo network and simulation settings. Specify theNetwork AddressasCustom,theHostname/IP Addressfor your Gazebo simulation, and aPortof14581, which is the default port for Gazebo. The desktop of the VM displays the IP address.

For more information about connecting to Gazebo to enable co-simulation, seePerform Co-Simulation between Simulink and Gazebo.

Click theInitialize Modelbutton at the top of the model to intialize all the variables declared above.

Runthe simulation. The robot drives around the environment and stops whenever a worker gets within the defined threshold.