Intel Realsense D435i

How to use the Intel Realsense D435i robot skill

Connect the D435i Intel Realsense camera to the ARC Navigation Messaging System (NMS) for distance detection and mapping. This should also work with other Intel RealSense depth camera models because the FOV and parameters are used from the device.

Main Screen

1) Select the device by the serial number. This allows multiple Intel Realsense devices to be added to a project.

2) START/STOP button connecting to the RealSense device.

3) Log window for status and errors.

Image Align

The Image Align tab allows selecting the area of the image that you wish to detect for the point cloud. For example, having the detection too low will detect the floor at a close distance. Ideally, set the bar high enough to avoid detecting the floor.


1) Adjust the top of the detected image range.

2) Adjust the bottom of the detected image range.

3) detected image range is highlighted in purple.

Configuration

1) Offset of the T265 from the center of the robot. The positive number means the sensor is toward the rear; a negative number means the sensor is toward the front. The measurement is from the center of the robot. The sensor must sit aligned with the center of the robot, not toward the left or right. The sensor must face 0 degrees heading.

2) Sensor resolution during initialization. If the values are changed from the default, obtain them from the Intel RealSense viewer. Changing these values may be necessary if using a different sensor than the D435i. Set both width & height to 0 for auto-size, which isn't the most efficient for performance.

3) The number of depth pixels to skip when processing the depth data. This is useful for lower CPU PCs or when high-resolution depth is not required. Since there is a limited field of view (FOV) on the sensor, it may not be necessary to process every depth pixel. If the sensor resolution is 1280x720, the CPU would be processing 921,600 depth points for every scan of the specified framerate. At 1280x720 @ 15 FPS, that's 13,824,000 depth points per second. If the Skip Scan Points for X & Y are set to 10 for that resolution/fps, the CPU would only need to process 9,216 depth points per scan (or 138,240 per second).

The editor will recommend a value for the best balance between performance and detection based on the sensor FOV.

4) The camera video from the RealSense can be pushed into a selected Camera Device. In the selected camera device, choose CUSTOM as the device type. This will accept the video feed from this robot skill. Ensure START is pressed on the selected camera device as well.

Troubleshooting

If you experience any issues, ensure the USB 3 port is used on the computer. Second, load the Intel RealSense Viewer. There may be a prompt to "Enable USB Meta Data," which is a system-wide change. Ensure you answer ENABLE to that option. Lastly, update the firmware if there is a prompt to do so.

If the sensor works in the Intel RealSense viewer, it will work with this robot skill. Depending on the version of the sensor, you may need to configure the capture width/height/framerate. This can be done in the robot skill configuration screen. The RGB and Depth camera resolution values must be the same. You can use the Intel RealSense Viewer to see what values work for your camera. If the RGB camera is 640x480 x 15 FPS, the depth camera must also have a supporting resolution with the same settings. This is because this robot skill will parse the depth and RGB data together.

Variables

This skill will create four global variables that scripts can reference.



$D435IsRunning - status of the D435 robot skill if it is connected or not to the sensor.

$D435FurthestDistanceCM - furthest distance detected

$D435FurthestDistanceDegree - furthest degree of the furthest distance CM variable.

$D435NearestDistanceCM - nearest distance detected

$D435NearestDistanceDegree - nearest degree of the closest distance CM variable.

ARC Navigation Messaging System

This skill is part of the ARC navigation messaging system. It is encouraged to read more about the messaging system to understand available skills HERE. This skill is in level #3 group #1 in the diagram below. This skill contributes telemetry positioning to the cartesian positioning channel of the NMS. Combining this skill with Level #3 Group #2 skills for obstacle avoidance. And for Level #1, The Navigator works well.