What should the rover do when I switch to Auto mode? Should the motor start immediately?
In my case, I have to manually move the throttle stick to control speed all the way to the first WP.
The only param that seems applicable is AUTO_KICKSTART which is defined as follows:
X acceleration in meters/second/second to use to trigger the motor start in auto mode. If set to zero then auto throttle starts immediately when the mode switch happens, otherwise the rover waits for the X acceleration to go above this value before it will start the motor (values are 0-20)
My AUTO_ KICKSTART is set to zero, so I would assume from the above that the motor should start immediately when the "mode switch happens". Also I do not understand how the X acceleration would go above zero.
Replies
A couple of questions:
1) What are your cruise speed and cruise throttle set to? These *should* define your starting throttle when you kick it into AUTO mode.
2) Is there ANY servo output on the throttle channel when you switch it to AUTO?
3) When you switch to AUTO mode, is it updating the HUD to reflect the distance to the first waypoint, and are the heading lines on the map changing appropriately?
Thank you MikeRover for your help.
Note that I am not deliberately trying to Kickstart and my current Kickstart param = zero, therefore I am looking for normal throttle response to auto mode.
1. Current values: Cruise speed = 0.4, Cruise throttle = 1.0. I changed these to 1.0 and 10 just for a test and there was no change in behavior.
2. Yes, there is about one degree of servo deflection when moving from other modes to Auto.
3. Typical values for distance to WP vary with time and are:
Manual mode = 5-9
Learning = 5-9
Auto = 5-9
RTL = 49-54
My WP radius is set to 2.
My current thinking is that maybe my "playing field" is too small and that GPS, compass, and other ditherings are confusing the APM. Weather permitting, I am going to keep the same parameters and move to a larger field.
Thanks again for your input, I do appreciate it!
Follow up: Went to larger field and got same results as smaller field. I still have to use throttle in Auto mode.
I did confirm that RTL works as expected but once again had to use manual throttle in RTL.
@emile,
Put the CRUISE_THROTTLE at 30.
Regards,
TCIII ArduRover2 Developer
Thanks, TCIII, that seems to work. Any value below 13 does not work on the test stand. This probably depends on ESC used.
I suggest the default be set to 30 to keep other newbies from suffering the same mistake.
Now I can do some tuning!
Thanks again!
30% throttle on some vehicles can be extremely quick. It's much safer to default to zero and have people read the directions on throttle settup and tuning.
What's your SPEED2THROTTLE_IMAX set to? That should automatically ramp up if you've got the base CRUISE_THROTTLE set too low.
Also, 0.4m/s as a cruise speed may be too low for the GPS to accurately resolve - watch what the HUD reads as groundspeed when the vehicle is stationary.
@MikeRover,
As you say, 30% CRUISE_THROTTLE can make some vehicles start out quickly.
However, I found that with a 30% CRUISE_THROTTLE my Traxxas Slash Rover could go no faster than 6m/s and it took a CRUISE_THROTTLE setting of 45 - 50% to be able to obtain 9 - 10m/s.
Regards,
TCIII ArduRover2 Developer
Thanks, MikeRover.
1. My rover is based on a rock crawler with 4WS and FWD (I removed the RWD motor). Max speed is ~ 1.8 M/s on grass and 2.2 on hard surface. This is OK for me. I am more interested in pursuing smoothness and precision rather than speed. A Cruise_Throttle value of 16 to 24 works for me without wheel spin.
2. My SPEED2THROTTLE_IMAX is currently set to 4000 (default?). There are no comments on this param, so I do not have any idea as to what it should be or what it does. Any recommendations?
3. Static GPS ground speed varies over time from 0.03 to 0.49 M/s. It is never zero.
Even more questions:
1. I am seeing no noticeable ramp up or ramp down in speed in Auto mode. What params should I be looking at to control this?
2. Compass/GPS is Ublox Neo 6 and I am running it as received. Does this need calibration? I have FTDI cables, etc. but if it ain't broke, I don't want to brick it. ;-)
Thanks, as always for your help!
@emile,
I have found the default value for the SPEED2THROTTLE_IMAX parameter to be adequate for my Traxxas 4WD Slash Rover which weights between 5 and 10 pounds with the battery in place.
Regards,
TCIII ArduRover2 Developer
SPEED2THROTTLE_IMAX should (I think) be around 10-40 - it's the maximum percentage throttle the integrator will add to correct the delta between the nominal cruise throttl eand what's actually required to get you to speed.
Throttle slew rate will give you a slow ramp up:
Throttle slew rate (APMrover2:THR_SLEWRATE)
maximum percentage change in throttle per second. A setting of 10 means to not change the throttle by more than 10% of the full throttle range in one second. A value of zero means no limit. A value of 100 means the throttle can change over its full range in one second. Note that for some NiMH powered rovers setting a lower value like 40 or 50 may be worthwhile as the sudden current demand on the battery of a big rise in throttle may cause a brownout.
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