Preparing for the 2014 Sparkfun AVC ground vehicle competition

Hi All,

I have been tuning up my APM2.5 equipped Slash brushless 1/10 scale autonomous rover on my new pre-school parking lot test course. Tridge, Linus, and I are continually improving and testing the ArduRover2 firmware in anticipation of the upcoming 2014 AVC.

The only time that I manually command the rover with my transmitter during this video is to guide it back to the starting position for another run. I recorder three laps with this rover this morning here in Florida.

Here is a video of my winning Slash rover on my 1/8 mile test track. The rover was moving at 6 m/s on the straights with 11 sats and an HDOP of 1.4. Waypoint radius is 2 m.

This rover is capable of 10 m/s and I intend to work my way up to that speed during the month of March.

We also have a Pixhawk equipped Slash 2WD brushed rover that I am in the process of converting to a brushless 2WD rover. This rover will be equipped with two GPSs.

Regards,

TCIII ArduRover2 Developer

Hi All,

We will be competing in the Peloton Class again with our Traxxas Slash 2WD brushless rover chassis in this years AVC.

We have recently upgraded from an APM2.5 to a 3DR Pixhawk navigation processor and are using twin GPSs.

The GPS selection function is quite simple in that it uses the GPS with the most sats at any given moment which does not necessarily guarantee the best HDOP value, but is great for redundancy in that our tests have indicated that at least one sat will always have a lock at any given time.

We have also perfected an Active Braking function. Active Braking allows us to selectively apply reverse throttle (<1500us) when approaching a turn at a high speed to get the rover decelerated to a turn speed (~3m/s) that will not cause a rover rollover.

We can select the amount of breaking (Braking_Percentage) and the difference between the GPS speed and the requested speed (Speed_Err) at which active braking will occur.

I have been able to approach a 90 deg turn at ~9m/s and have the rover decelerate to 3m/s in less than 5m in order to make the turn without rolling over. Active Braking is also very effective in a chicane like how the barrels are placed on the AVC course.

We have also been evaluating DCM heading estimation vs EKF heading estimation and have found that the EKF function virtually eliminates post turn oversteer and provides exceptionally accurate turns.

We do not plan to use line following, but I might fall back to my twin sonars for obstacle avoidance at low speeds.

However I feel that accurate GPS position knowledge of the barrels, hoop, and the ramp along with course practicing on Friday afternoon and Saturday morning will help to optimize the course waypoints.

I believe that the competition is going to be very tough this year compared to last year.

Regards,

Tom C ArduRover2 Developer

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Admin

Thomas J Coyle III May 22, 2014 at 7:32pm

Hi All,

We will be competing in the Peloton Class again with our Traxxas Slash 2WD brushless rover chassis in this years AVC.

We have recently upgraded from an APM2.5 to a 3DR Pixhawk navigation processor and are using twin GPSs.

The GPS selection function is quite simple in that it uses the GPS with the most sats at any given moment which does not necessarily guarantee the best HDOP value, but is great for redundancy in that our tests have indicated that at least one sat will always have a lock at any given time.

We have also perfected an Active Braking function. Active Braking allows us to selectively apply reverse throttle (<1500us) when approaching a turn at a high speed to get the rover decelerated to a turn speed (~3m/s) that will not cause a rover rollover.

We can select the amount of breaking (Braking_Percentage) and the difference between the GPS speed and the requested speed (Speed_Err) at which active braking will occur.

I have been able to approach a 90 deg turn at ~9m/s and have the rover decelerate to 3m/s in less than 5m in order to make the turn without rolling over. Active Braking is also very effective in a chicane like how the barrels are placed on the AVC course.

We have also been evaluating DCM heading estimation vs EKF heading estimation and have found that the EKF function virtually eliminates post turn oversteer and provides exceptionally accurate turns.

We do not plan to use line following, but I might fall back to my twin sonars for obstacle avoidance at low speeds.

However I feel that accurate GPS position knowledge of the barrels, hoop, and the ramp along with course practicing on Friday afternoon and Saturday morning will help to optimize the course waypoints.

I believe that the competition is going to be very tough this year compared to last year.

Regards,

Tom C ArduRover2 Developer
Admin

Thomas J Coyle III March 9, 2014 at 11:59am

Hi All,

This video demonstrates the capabilities of a 3DR APM2.6 equipped Traxxas E-Maxx 1/8 scale brushless autonomous rover. The rover reached a speed of around 7 m/s in the straightaways and negotiated three chicane waypoints while traversing the 1/8 mile course. The Crusher can easily reach speeds of ~28 m/s, but I am shooting for good performance in the straightaways and chicanes at 10 m/s.

I hope to enter this E-Maxx Crusher in the AVC Doping class this year at Boulder.

Regards,

TCIII ArduRover2 Developer

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ArduRover User Group

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