Pi Zero Drone: Part 9

Quad Post #9: Calibrating ESC Manually
Each of the ESCs (Electronic Speed Controllers) on the quadcopter has to be calibrated to the RC transmitter signal so that the full range can be read on the quadcopter. To start the calibration procedure first ensure the following steps are done prior to ESC calibration
  •     Bind RC transmitter to receiver and calibrate the transmitter using the steps from blog post #8.
  •       Disconnect ALL propellers from the quadcopter.
  •       Disconnect any external power source i.e. USB cables from computer and Li-Po battery.

    This method of ESC calibration is referred as the “All At Once” method. Here are the steps:
  1.       Turn transmitter on, and set the throttle to maximum.
  2.       Plug in Li-Po battery.
  3.      Wait for the 3 signal LEDs on the PXFmini to start light up in sequence
  4.      Once the LEDs illuminate, disconnect the battery. (Keep throttle at maximum!)     
                     The ESCs are now in calibration mode

            5 .       Reconnect the battery and wait for LEDs to light up in sequence and buzzer will sound.
            6.   Once buzzer and LEDs light up in sequence, move the throttle to minimum
            7.   You now have full control of the motors with new ESC calibration. 

Pi Zero Drone: Part 8

Pi Zero Drone Post 8: On board Instrument Calibration
From the on screen response to tuning PID controllers, APM Planner 2.0 software can give a newbie quad user (myself) a deep understanding of what it takes to control this quadcopter. The software is capable of display real time response of the IMU, RC controller and other instruments you wish to fly with. This post aims to give a brief introduction and how to calibrate your instruments while I wait for new ESC to come in from Amazon.
The APM Planner 2.0 has a very interactive GUI that can be used for multiple vehicle types. A full in depth tutorial of the software can be found on ardupilot.org/planner2/. First step is to download the software onto your computer and follow the instructions on the screen. To connect to the quadcopter, first plug in the battery and wait for the buzzer to sound. This time you can connect to your quadcopter using the 5 GHz Wi-Fi signal.

Steps to configure the Wi-Fi signal can be found in blog post # 6.

After you have connected, the on screen altitude indicator (Very similar to one on an airplane) should start responding to the onboard IMU. Now the calibration can begin. In the APM Mission 2.0 tool bar select ‘Initial Setup’ >> Mandatory Setup. From here you can pick the frame type, this drone uses the first X-style frame type.

Select Compass to start the calibration. The Compass will need a live calibration by rotation the quadcopter in the air slowly around all axis (front, back, left, right, top and bottom). This will be done for 1 minute. Calibration offset will be created and stored for future missions.  

Selected Accel Calibration and the calibration wizard window will appear. Be sure to have the quadcopter on a flat surface and select Calibrate Accelerometer and follow the prompts on the screen. It is important not to move the copter immediately after pressing continue for each process, this may lead to skewed stored parameters.

Radio Calibration
Remove all propellers and bind the RC transmitter to the receiver.
Select Radio Calibration and start the calibration by pressing the Calibrate button. Move the sticks and switches to the maximum positions. When you feel that all the movements are correct, press End Calibration and the offsets will be stored for that radio controller.
Attach “RC_Calibration.jpg” here
Flight Modes
This setting can be used to assign switches on your transmitter to modes like loiter or stabilize. You can set your own settings based on what you wish your quadcopter to do.

Power Wheels Racer Post-Race Update

So I did not really keep up with posting about all that has happened with the car lately but now that we are back and unpacked from Maker Faire I am going to update everyone on what we did. As far as the race goes in Orlando we had a great time up there and all the cars everyone brought were awesome. Here is a short video of the race so that you guys can see all the cars!

Although our car had some speed we actually were not able to finish the race due to burning our speed controller. Basically what happened was the connector that was between the forward and reverse and the speed controller melted from the motor running as long as it had to during the race. As that plug melted the two copper lead got closer and closer together until the shorted the wires running out on the speed controller this short then caused the speed controller to burn up. Here are some pictures of the damage. 

So after we really didn't think we had any chances of racing again. We had no replacement speed controller and after calling a few places in the Orlando, the internet was really the only place that we were going to find a 36V 1000W motor controller, but we didn't have time to wait for shipping. Then after talking to some of the other racers the guys over at Familab told us they may have a spare speed controller at their makerspace and they would let us borrow it if we came by to check out the lab. We took them up on the offer. They have a really cool setup over there with a lounge and hangout area plus some really awesome machines in the back. They had a manual mill and lathe, a CNC mill, one really big 3D printer, and lots more. I would highly recommend giving their lab a look if you are in the Orlando area.  And they let us snag a Kelly Controller 24V 400A speed controller to try to rig up on Sunday morning. We found a wiring diagram from Kelly controllers website and tried to follow it as best we could. We actually had to drive back to their space to grab a few extra parts. There was a main contactor, a few diodes, and a precharge resistor. After we had all we needed we still weren't quite able to get it back up and running that weekend.

Since Maker Faire, we ordered a new speed controller and decided to add a voltmeter and ammeter to the car so the diver might have some idea of what is going on back there. While I was driving I really had no idea that something was wrong until the motor locked up from the leads touching. Here is a link to the one we got below.


That shunt that comes with it is basically just a really tight tolerance, low resistance resistor so that the meter can measure the voltage drop across it to get the current. If you want to know more about that resistor look up manganin resistors, they were actually used in determining the standard for the ohm back in the early 1900's. Also, Bryan made an Arduino circuit with a few temperature sensors so we can display the heat at a few different places in the circuit on the dash too. With the temperature, voltage, and current readings we are going to hopefully be able to diagnose any problems the vehicle has in the future faster and catch them before a controller looks like it got left in the oven too long (see picture above).