MultiSense KS21 Manual : ROS Driver

4. Troubleshooting

Symptom	Recommended Action	Explanation
No communications with the MultiSense KS21	Check that NetworkManager is not running, and stop it if necessary using the command sudo stop network-manager. Then reconfigure the network as described in Starting the Driver.	NetworkManager periodically checks network configuration, and may change network settings unpredictably, interrupting communications with the MultiSense.
No images received	Check network MTU size on connected computer using the ifconfig command. Verify that MTU size is set to 7200.	Some network cards do not support setting large MTU sizes. Use an Intel NIC if possible, see note below for details.
Try plugging the Ethernet cable from the MultiSense directly into the host computer, then move to a higher quality network switch.	The current communications protocol is quite sensitive to dropped packets. Competing network traffic or poor connections can easily result in no images being received.
No images received, inconsistent frame rate, or low image frame rate	Try increasing the size of the kernel’s networking RX buffers by adjusting /proc/sys/net/core/rmem_max. See Starting the Driver and the configureNetwork.sh script for more details.	The KS21 can generate large amounts of UDP traffic that may overwhelm typical network settings on some machines. Use an Intel NIC if possible, see note below for details. We have found that Realtek NIC drivers / hardware start dropping images from the MultiSense when frame rate goes above 5 FPS.
Sensor not displayed in RViz	Navigate to the directory where the MultiSense stack is installed, source the setup.bash file, and restart RViz.	RViz was run in a terminal in which the ROS environment did not include the MultiSense stack.
When recording at high frame rate (e.g. 30 FPS), sometimes frames are dropped	ROS has difficulty recording data to disk at the same time as flushing internal buffers, causing some frames to be lost and not written to disk.	Record your bag file to a fast SSD or TMPFS partition, instead of to a standard internal disk.

Symptom

Recommended Action

Explanation

No communications with the MultiSense KS21

Check that NetworkManager is not running, and stop it if necessary using the command sudo stop network-manager. Then reconfigure the network as described in Starting the Driver.

NetworkManager periodically checks network configuration, and may change network settings unpredictably, interrupting communications with the MultiSense.

No images received

Check network MTU size on connected computer using the ifconfig command. Verify that MTU size is set to 7200.

Some network cards do not support setting large MTU sizes. Use an Intel NIC if possible, see note below for details.

Try plugging the Ethernet cable from the MultiSense directly into the host computer, then move to a higher quality network switch.

The current communications protocol is quite sensitive to dropped packets. Competing network traffic or poor connections can easily result in no images being received.

No images received, inconsistent frame rate, or low image frame rate

Try increasing the size of the kernel’s networking RX buffers by adjusting /proc/sys/net/core/rmem_max. See Starting the Driver and the configureNetwork.sh script for more details.

The KS21 can generate large amounts of UDP traffic that may overwhelm typical network settings on some machines. Use an Intel NIC if possible, see note below for details. We have found that Realtek NIC drivers / hardware start dropping images from the MultiSense when frame rate goes above 5 FPS.

Sensor not displayed in RViz

Navigate to the directory where the MultiSense stack is installed, source the setup.bash file, and restart RViz.

RViz was run in a terminal in which the ROS environment did not include the MultiSense stack.

When recording at high frame rate (e.g. 30 FPS), sometimes frames are dropped

ROS has difficulty recording data to disk at the same time as flushing internal buffers, causing some frames to be lost and not written to disk.

Record your bag file to a fast SSD or TMPFS partition, instead of to a standard internal disk.

Note that Carnegie Robotics highly recommends using Intel Network Interface Cards (NICs) and not NICs from other vendors like Realtek. We have found that Realtek drivers and or hardware start dropping images from the MultiSense when frame rate goes above 5 FPS. On ARM-HF based system, use of Realtek NICs have prevents reception of MultiSense image streams.