Background:
I have a Traxxas Stampede that I am using for a test platform for the AMP 2.5. I’ve upgraded to the brushless Velineon VXL-3s motor and controller, and am using a Futaba 9C with FrSky 2.4G TX/RX. The APM 2.5 is mounted to an ABS platform three inches above the frame to isolate from motor/ESC. I have a telemetry system on order but want to get everything else working before I install it and complicate things any further.
Question:
I’m trying to get the system to work using just the Futaba/FrSky TX before I start loading waypoints with the MP. When I’m out in the field, how do I delete any waypoints I’ve saved using the 3-position Channel 5 toggle? Sometimes I want to delete all waypoints and start over? Would the APM 2.5 Reset button do that? Or is there a way to delete waypoints without a total reset?
Question:
How close together can I make the waypoints? I’d like to make a waypoint every 4-5 meters to keep the rover on a trail through some woods (I’ll eventually add sonar to help keep it centered in the trail). What parameters need to be adjusted for the APM 2.5 to be effective for waypoints placed this close together?
@Falcon,
When you are in the field you can use the “learn” 2-way switch to delete the waypoints in the APM’s memory. All you have to do is have the 3-way mode switch in manual then toggle the 2-way switch which will erase any waypoint stored in the APM’s memory.
The spacing of the waypoints is determined by the waypoint radius setting in the Mission Planner in the MP. The smaller the waypoint radius setting, the closer together the waypoints can be. Usually setting the waypoint radius between 1 and 2 meters works for most missions.
I appreciate the reply. After reading it I found that bit in the “APM: Rover Code and Configuration” WIKI page. I thought I’d looked everywhere.
So far I’ve had limited sucess. I think the leaf cover in these woods are limiting my GPS accuracy. I’ve heard of people getting a GPS lock indoors so I figured the woods wouldn’t be too much of a problem.
@Falcon,
The brand of GPS that you are using is everything when you want maximum accuracy.
All of my navigation GPSs on my rovers are uBlox LEA-6 except one which is one of the newer uBlox. With a uBlox LEA-6 I can get 7 - 9 sats indoors depending on the amount of cloud cover. Less cloud cover, more sats, better HDOP. The latest uBlox that I have has given me 10 sats indoors on a very cloudy day when I could not see the sky.
Also, I have a small metal ground plane under each GPS that helps to increase the received sat signal strength.
Dense foliage on trees and bushes can really suck up the sat signals. Also, if you have surrounding foothills or mountains, they can reduce the number of sats that can be seen at anyone time.
I just took delivery of my APM 2.5 last week and chose the uBlox, so I should have the LEA-6. Where did the newer one come from, and was it a plug-n-play swap?
I’ll try that trick with the metal plate. Does it help more by concentrating the received signal or shielding from the motor/ESC?
No mountains around here but I am on a gentle slope.
@Falcon,
The newer uBlox GPS is part of the new combination GPS/compass which has been made available to developers recently. The combination GPS/compass should be available in the new 3DR store early next week.
The GPS really only needs to be shielded from high power video transmitters. A small, thin metal plate, slightly larger than the GPS, mounted under the GPS will work fine.
Home position is the location where the GPS makes it’s initial satellite “lock”. Is that correct?
If I drive the rover around and set three waypoints, where does it head to when I switch to Auto mode: Home or WP 1? Does the Home position really mean anything as far as the actual navigation?
Also, when mounting the uBlox LEA-6 GPS, will the reception be reduced significantly if the unit is mounted with the LEDs facing down?
@Falcon,
When I first start my rove I let it get a 3D lock then I move it to the home point that I have programmed in the waypoint file.
After you have entered waypoints in the learning mode, the rover should start at the home waypoint, no matter where it is, when you enter the auto mode.
The uBlox GPS receiver should be mounted with the antenna on the top and the leds on the bottom. Also a piece of aluminum or copper under the GPS will help as a ground plane.
Regards,
TCIII Admin