I was searching for GPS and IMU support on RTAB-Map, and I guess it does have from some papers I read, however on the official package documentation http://wiki.ros.org/rtabmap_ros no GPS or IMU related topics are documented. I did find a question here where Matt himself (the main RTAB-Map maintainer, I guess) said a GPS topic did exist back in 2019:
The input gps topic to rtabmap node is called /rtabmap/gps/fix, which is a sensor_msgs::NavSatFix type.
I wonder if anyone knows if it was deprecated in the meanwhile, and if so, why.
Thanks.
EDIT: I read some people suggesting "robot_localization" and feeding the output into RTAB-Map's odometry input. Is this now the only way?
Related
Required Info
Camera Model
D435
Firmware Version
05.12.13.50
Operating System & Version
Linux (Ubuntu18.04.5)
Kernel Version (Linux Only)
4.9.201
Platform
NVIDIA JetsonNano B01
SDK Version
2.41.0
Language
ROS packages }
Segment
Robot
Hello, I need to use the obstacle avoidance function in the process of using D435. At present, there are two ways I have inquired:
1、Use depthimage_to_laserscan to convert the depth information into a lidar signal, but the current problem is that there is also a lidar on my robot. Now these two topics are scan, so there is a conflict. I don't know how to solve it.
2、I want to know whether the two lidar signals can be fused, and what configuration is needed to be fused. Is there any relevant information or code?
3、Using plotcloud2 point cloud information, I don't understand how to do this at present. Although the point cloud image can be seen on the map now, it does not have the effect of avoiding obstacles. And does this point cloud information need to be passed to AMCL? If so, how does it need to be delivered? So I hope someone can help me.
every one i have knowledge about DAQ but my main question is which type of Thermo couple i used for NI DAQ devices and i there some link to buy it online,
waiting for your kind Response
You can read about thermocouple types here. These are all the current temp-sensing module options. You'll have to dig into documentation here to determine which type of thermocouple will be required.
I am trying to access the physical un-calibrated gyroscope sensor. But I am unable to. Since I can only access the calibrated one, I want to know what method is used for drift compensation in the gyroscope sensor used in the Tango Device.
Nobody knows exactly what Tango uses for drift compensation, my own guess would be that they are heavily reliant on Structure From Motion techniques. If you're asking how to calibrate an already calibrated gyro (calibration quality is a different issue :-) ), that's a topic for an entire stack overflow site, not a single answer :-) And it would leave you battling for computation resources with Tango - if you want to experiment, any phone with 3DOF attitude sensing and a decent camera is a good starting platform for learning about this, but be warned - it's really complex - much nicer to have it packaged and take what you get.
Working with multiple Kinect v1 sensors is very difficult because of the IR interference between the sensors.
Based on what I read on this gamastura article, Microsoft got rid of the interference problem with the time-of-flight mechanism that Kinect v2 sensor uses to gauge depth.
Does that mean I could use multiple Kinect v2 sensors at the same time, or did I misunderstand the article?
Thanks for the help!
I asked this question, in person, of the dev team at the meetup in San Francisco in April. The answer I got was:
"This feature is 3+ months away. We want to prioritize single-Kinect features before working on multiple Kinects."
I'm a researcher, and my goal is to have a bunch of odd setups, so this is a frustrating answer, but I understand that they need to prioritize usage that will be immediately useful to a larger market.
Could you connect them to multiple computers and stream data back and forth?
As #escapecharacter mentioned not likely to have support for multiple kinect v2 sensors in the very near future.
I can also confirm, one of the Kinect V2 SDK samples has this comment:
// for Alpha, one sensor is supported
this.kinectSensor = KinectSensor.Default;
I think the hardware itself is capable of avoiding the interference problem. Hopefully the slightly larger amount of data (higher res RGB stream) won't be a problem with multiple sensors(and available USB bandwidth) and it would be a matter of enabling the SDK to safely handle multiple sensor instances in the future.
I wouldn't expect a fast/quick update to the SDK enabling though, so in the meantime, although not ideal you could try either:
Using multiple V2 sensors on multiple machines communicating over a
local network, passing only processed/minimal data (to keep the delay
as small as possible)
Using multiple V1 sensors using Shake'n'Sense (pdf link to paper) to reduce interference
At least you would to a certain extent make some progress testing some of your assumptions for your project with multiple sensors, and update the project when the updated SDK is out.
I realize I misread your question, and interpreted it as "how can I connect to Kinect 2's to a computer" when you were actually asking about how to avoid interference, and Kinect 2 was your hoped-for solution.
You can hack avoiding Kinect 1 interference by lighting shaking one of them independent of the other. See here:
http://channel9.msdn.com/coding4fun/kinect/Shaking-some-sense-into-using-multiple-Kinects-with-Shake-n-Sense
One of the craziest things I've ever seen that actually worked. I was at Microsoft Research when they figured this out, and it works quite well.
You can have a Kinect v1 viewing the same scene as a Kinect v2 without interference. I know this isn't exactly what you're looking for, but it could be useful.
2 Years later, and this still cannot be done.
See:
https://social.msdn.microsoft.com/Forums/en-US/8e2233b6-3c4f-485b-a683-6bacd6a74d53/how-to-prevent-interference-between-multiple-kinect-v2-sensors?forum=kinectv2sdk
https://github.com/OpenKinect/libfreenect2/issues/424
As stated in the second link,
What happens is this: Each Kinect v2 continuously switches between different modulation frequencies. When two Kinects switch to the same frequency range, the interference occurs. They typically gradually drift into the same range and after a while drift out of that range again. So, theoretically, you just have to wait a bit until the interference is gone. The only way I found to stop the interference immediately was to disconnect (and reconnect) the concerned Kinect from its power supply
...
Quite unfortunate that these modulation frequencies aren't controllable at this time. Let's hope MS surprises us with that custom firmware
IIRC, I came across a group at MIT that got custom firmware from MS which solved the problem, but I can't seem to find the reference. Unfortunately, it is not available to the public.
I think we cant use multiple Kinect v2 in same environment because they will interfere lot comparatively kinect v1. As Kinect v2 depth sensing based on time of flight principle, multiple kinect v2 will interfere lot. For kinect v1 interference is not that much severe.
I've been looking for a detailed description for how USB protocol and cabling works for a long time with no luck. I am looking for a detailed yet not overcomplicated explanation of how things work on the software and hardware side of USB. Links and explanations would be appreciated. I've really run out of ideas, so it would be great if you can help me out.
This is what I do know:
USB hardware carries 4 lines- 5V power, ground, and 2 full duplex lines.
When connecting, the device can ask for a specified amount of current.
The transfer speeds for USB are quite fast compared to traditional serial connections.
When connecting, a device will output descriptors to the host describing itself. These descriptors will also be used for data.
What I don't know:
How does a program in C/C++ write directly to a USB port? Does it write to an address in the port?
How do some devices describe themselves as HID?
How do drivers work?
Everything else...
Thank you!
Identification
Every device has a (unique) Vendor and Product ID. These are provided (sold) by usb.org to identify a device. You can use a library like libusbx to enumerate all connected devices and select the one with the Vendor and Product ID you are looking for.
HID Descriptors
The point of HID descriptors is actually to do away with drivers. HID descriptors are a universal way of describing your device so you don't need to waste time on a driver for every system/architecture/etc/. (Same concept as the JVM.)
Reports
You will use either the input, output, or feature reports to read or write to your device. You send a stream to your device on the input or feature report. This is typically 8 bytes I believe. Only one of which is a single character you wish to write. The HID descriptor contains all the information you need to put together a report. Although I'm struggling to find a related link to clarify this.
Potential Libraries
In an effort to be open-minded here are all the libraries I am familiar with and some info about them.
libusb-0.1
First off is libusb-0.1. This used to be the go to and was built in to many Linux kernels and Windows I believe. It is very easy to use and there is a lot of documentation. However, the owner never updated and it wasn't edited for many years. It supports only synchronous transfers. (If an error occurs, the program can wait infinitely while it expects a transfer.)
libusbx
Next is libusbx. This is what most people would suggest today and I agree. It was published by those frustrated by the owner of libusb-0.1. The code is much more lightweight, up-to-date, and importantly does not require root privileges like libusb-0.1 and libusb-1.0 (Discussed in a second). It supports synchronous or asynchronous transfers.
libusb-1.0
Then there is libusb-1.0. This was the first update to libusb-0.1 in some number of years. It is not compatible with libusb-0.1. This was published the same day as libusbx as a retaliation (I assume) and an attempt to rectify the lack of updated content and conserve a user-base. It supports synchronous or asynchronous transfers.
hid.h
Finally, there is the hid library. This was built on top of libusb as another layer of abstraction. But honestly, I think it's just really confusing and it just adds more overhead than necessary.
Some Good Resources
Understanding HID Descriptors
Control Message Transfer Documentation (Very Good Link IMO)
Rolling Your Own HID Descriptor
Good Visual of HID Reports for Transfers
Great List of bmRequestType constants (You will need this or similar)
A simple terminal app for speaking with DigiSpark using libusbx and libusb-0.1
I know this isn't exactly what you are looking for, but maybe it will get you started!
This website has a general overview of how USB devices work:
https://www.beyondlogic.org/usbnutshell/usb1.shtml
Particular sections give answers to things from the list of things you don't know yet about USB.
E.g. to find out how USB devices identify themselves, read about USB descriptors:
https://www.beyondlogic.org/usbnutshell/usb5.shtml#DeviceDescriptors
To learn how a C/C++ program can talk to a USB device, see examples on using the libusb library:
https://github.com/libusb/libusb/tree/master/examples
To learn how USB drivers work, see a tutorial from Bootlin:
https://bootlin.com/blog/usb-slides/