6 - Problems Encountered
As with any other project, we ran into a handful of noteworthy problems. Fortunately, we found a solution for each one.
Vehicle Oscillation
We finally loaded our first mission into Bebop. We set waypoints so that it would drive around our practice course, run through our simulated hoop, jump the ramp, and then return to the start point. To our horror, Bebop drove off with a violent steering oscillation! It was the kind of driving you would expect from a road raging commuter determined to start a vehicle rollover.
Although Bebop would maintain a generally straight path while aggressively weaving left and right, the oscillations were troublesome whenever Bebop tried to perform a 90-degree turn. Sometimes it would make the first turn; sometimes it totally wiped out. Needless to say, Bebop wasn't ready for prime time.
Fortunately, we found a solution after some trial and error. (Again, spare batteries helped immensely.) We experimented with different PID settings on the Configuration > ArduRover Pids screen. Once we set the 'D' values for 'Steer 2 Servo' and 'Heading 2 Steer' to zero, everything seemed to fall into place. Drunk driving: resolved.
Here are our final ArduRover PID settings. These are the same settings we competed with.
Although Bebop would maintain a generally straight path while aggressively weaving left and right, the oscillations were troublesome whenever Bebop tried to perform a 90-degree turn. Sometimes it would make the first turn; sometimes it totally wiped out. Needless to say, Bebop wasn't ready for prime time.
Fortunately, we found a solution after some trial and error. (Again, spare batteries helped immensely.) We experimented with different PID settings on the Configuration > ArduRover Pids screen. Once we set the 'D' values for 'Steer 2 Servo' and 'Heading 2 Steer' to zero, everything seemed to fall into place. Drunk driving: resolved.
Here are our final ArduRover PID settings. These are the same settings we competed with.
Manual Mode Trim
Bebop has survived many collisions, but each collision takes its toll on the chassis. With enough repeated collisions to the front wheels, Bebop's steering became slightly misaligned. It began steering more towards the right while in Manual Mode. (This problem appeared to be automatically corrected by the APM software while driving in Auto Mode.) With the stock transmitter, we could easily cure this by adjusting the steering trim knob more towards the left. But since we've done away with the stock transmitter and receiver entirely, we had to adjust the Turnigy transmitter settings. Here's how:
1 - Ensure that all of the toggle switches are flipped up and away from you. Then, turn on the transmitter. Afterwards, turn on the rover.
2 - While at the home screen, press and hold the MENU button until the menu appears.
3 - Press the DN button to highlight the wrench/screwdriver icon, and then press MENU.
4 - Press the DN button seven times to highlight the [TRIM] option, and then press MENU.
5 - Use the + and - buttons to adjust the trim value for the aileron setting (AIL).
6 - Press MENU to save the changes. Try driving the rover to see if the trim setting is enough. If not, adjust it again. We eventually settled on a value of 40.
7 - Once all changes are complete, press EXIT twice to return to the home screen. You should see that the arrow on the aileron trim setting (towards the bottom-right) has moved off-center.
1 - Ensure that all of the toggle switches are flipped up and away from you. Then, turn on the transmitter. Afterwards, turn on the rover.
2 - While at the home screen, press and hold the MENU button until the menu appears.
3 - Press the DN button to highlight the wrench/screwdriver icon, and then press MENU.
4 - Press the DN button seven times to highlight the [TRIM] option, and then press MENU.
5 - Use the + and - buttons to adjust the trim value for the aileron setting (AIL).
6 - Press MENU to save the changes. Try driving the rover to see if the trim setting is enough. If not, adjust it again. We eventually settled on a value of 40.
7 - Once all changes are complete, press EXIT twice to return to the home screen. You should see that the arrow on the aileron trim setting (towards the bottom-right) has moved off-center.
Hardware Troubles
There were two hardware problems we had to address.
First, the APM module had a bad habit of falling apart. The plastic cover would not hold together; the attachment screws kept falling out. They appeared to be a size too small for the receiving holes. We applied some Krazy Glue inside the screw holes and along the edge of the case (where the top piece joins the bottom piece). Now the case is permanently attached, which is fine. We shouldn't have to dig around on the board itself any time soon.
Our other problem was with the telemetry kit. The ground station unit (which plugs into the laptop) would not connect with the rover-side unit. We tried using the 3DR Radio Config utility to troubleshoot it, but without success. Fortunately, the 3D Robotics support team was helpful. After explaining the issue with supporting pictures and video, we were able to ship our troublesome transmitter to them and have a replacement sent to us in time for the SparkFun competition. Having a working telemetry system finally allowed us to start monitoring Bebop while it was executing missions.
First, the APM module had a bad habit of falling apart. The plastic cover would not hold together; the attachment screws kept falling out. They appeared to be a size too small for the receiving holes. We applied some Krazy Glue inside the screw holes and along the edge of the case (where the top piece joins the bottom piece). Now the case is permanently attached, which is fine. We shouldn't have to dig around on the board itself any time soon.
Our other problem was with the telemetry kit. The ground station unit (which plugs into the laptop) would not connect with the rover-side unit. We tried using the 3DR Radio Config utility to troubleshoot it, but without success. Fortunately, the 3D Robotics support team was helpful. After explaining the issue with supporting pictures and video, we were able to ship our troublesome transmitter to them and have a replacement sent to us in time for the SparkFun competition. Having a working telemetry system finally allowed us to start monitoring Bebop while it was executing missions.
Last Update: 30 November 2013