I am planning to try the dual sonar option on the latest ardurover version. I am following the instructions on this forum. Does the dual sonar work ? My max vehicle speed is 2.1 m/s so I think it should be fine. Comments ?
Also, is there anyone using a RTK GPS with ardurover. I understand there is some issue with hires waypoints that Tridge is busy solving. From the internet chatter I think that Piksi is not ready for prime time but perhaps someone has used a commercial cm-level GPS ?
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i made it reverse....otherwise the left become right... :)
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@Bob,
Nice rover:-)
Regards,
TCIII AVD
@Heliboy,
If you are using a Pixhawk, here is how to install dual sonars: Link
Regards,
TCIII AVD
Thanks for all the help. I will try to mount the sonars later today. The need to trigger each one separatly is a pain and will cause response delays. My application is to crawl along a fence line. I was wondering if I could make two whiskers (steel rod mounted on turnswitch) - one on either side and send the signals to the sonar channels. Whenever a whisker touches an obstacle (fence post) the voltage goes low and it triggers the evasive action set up in the sonar parameters. Sort of a cockroach robot. Think this would work ? I would put a another sensor pointing towards the front to prevent a headon collision.
@Heliboy,
The Pixhawk/APM ArduRover firmware is only configured for two sonars.
When using dual sonars if the right sonar sees a target then the rover will turn left a variable number of degrees. If the left sonar sees a target then the rover will turn right a variable number of degrees.
I originally built a three sonar setup, but used an Arduino to sense the sonar outputs and steer away from a detected target.
I used the output (steering/throttle) of a APM loaded with the ArduRover firmware to provide steering/throttle input to the Arduino. As long as there were no detected targets the Arduino passed the APM steering/throttle commands to the steering servo and the ESC.
If a target was detected then the Arduino took over and provided steering and throttle commands to the steering servo and ESC to avoid the detected the target. After avoiding the detected target the Arduino would then accept steering/throttle commands from the APM.
The only problem with this approach is the APM, after target avoidance by the Arduino, might steer you right back into the detected target as it tried to reestablish the rover heading to the presently loaded waypoint when in the Auto mode.
Regards,
TCIII AVD
Dual Sonar works. Have a look for Tom Coyle's Slash rover to show how its setup. I'm am also about to fit dual analogue sonar's to one of my rovers - should be great fun!
Dual GPS which we support is not RTK GPS. Dual GPS is simply 2 GPSs for redundancy and better reliability. For the OBC we mounted the 2 GPSs next to each other one 180 rotated to the other. If one of the GPS's has at least 2 more satellites then the other we switch to it as the primary. We fly for a long time. Its a rough environment for electronics so for the cheap cost of a second GPS it was a no brainer for us.
People have gotten the Piksi's to work. I have a set on my desk slowly gathering dust (my kingdom for more time!) but they should work just fine. Search the forum's and you will find users who have fitted them. They should be more accurate then a standard GPS.
The issue regarding "hires" waypoints is a datatype issue. Basically the datatype we use to represent the co-ordinates can only hold enough numbers to be accurate to around 1m. See this issue:
https://github.com/diydrones/ardupilot/issues/1907
We NEED to see a photo of that golf machine - sounds awesome!
Thanks, Grant.
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