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Overview
In Lab 11, lab groups simulated the avionics, controls, and motors used in the Believer aircraft, focusing on powering, arming, and ensuring proper connection and calibration of the system components. The lab involves setting up and calibrating the DATX, verifying its inputs and outputs, and ensuring proper parameter settings in the hardware and LUA script. The groups also created a mock-up of the Believer's avionics by connecting sensors to the Cube and testing system health, mapping control inputs to servo outputs, and preparing tables for RCMAP_X and SERVO#_FUNCTION parameters. Additionally, crews set up the motors and controls by connecting servos and ESCs, calibrating the ESC according to the provided guide, and testing motor function with a throttle ramp-up. The lab concludes with updating the team wiring diagram and submitting a comprehensive lab report with calibration evidence, answers to questions about the system setup, and an e-Portfolio reflection, to be exported as a PDF for assessment.
The lab group practiced powering and arming the system. An armed system can spin up the motors. The throttle should always be pinned.
Resources
Ardupilot Parameters
Open Link
Servo
Open Link
ESC
Open Link
Motor
Open Link
RX/TX
Open Link
Cube Wiring Quick Start Guide
Open Link
Servo Functions
Open Link
ArduPilot Overview
Open Link
Tables
Default parameter settings:
Parameter and Mapping
Name
Current Setting
Notes
SERVO1_FUNCTION
FlaperonRight
Open
SERVO2_FUNCTION
FlaperonLeft
Open
SERVO3_FUNCTION
Throttle
Open
SERVO4_FUNCTION
Throttle
Open
SERVO5_FUNCTION
VTailLeft
Open
SERVO6_FUNCTION
VTailRight
Open
SERVO7_FUNCTION
RUDDER
Open
RCMAP_BRAKE
0
Open
RCMAP_FLAP
5
Open
RCMAP_PITCH
2
Open
RCMAP_ROLL
1
Open
RCMAP_THROTTLE
3
Open
RCMAP_YAW
4
Open
There are no rows in this table
Input and Control
Input
Output
Notes
Right Stick
Flaperon Left &Right, VTail Left & Right
Open
Left Stick
Flaperon Left &Right, VTail Left & Right
Open
Pitch Up
Vtail Left & Right
Open
Pitch Down
Vtail Left & Right
Open
Throttle Up
Servo Output 3/4
Open
Throttle Down
Servo Output 3/4
Open
There are no rows in this table
DATX Setup
To setup the DATX controller correctly, the group first had to understand some basic controller theory. This included the introduction of CRSF and SBUS and their differences. CRSF is a full-duplex protocol that supports integrated telemetry and a number of other features. SBUS is serial bus protocol. The differences are that SBUS uses one wire while CRSF uses four, and CRSF tends to have faster update rates and two way communication. Another interesting item on the same topic is Multi-Bind on the TBS Tracer. Multi-bind on the TBS tracer allows the same transmitter module to stay paired with multiple receivers at once. This could become a very helpful tool in more complex operations in the future.
To properly set up the DATX, the group started by calibrating the DATX and ensuring that proper parameters were set. This was accomplished after a number of steps, the first of which included powering on the DATX. Then, the group moved the control sticks around and observed and noted where the DATX believes the sticks were. The group navigated to the “HAREWARE” screen and performed a sticks calibration. Shortly thereafter, the crew navigated back to the home screen and ensured that the controller was calibrated by moving the sticks and observing the onscreen position indicator. The group then navigated to the LUA Script and clicked on the “Tracer Micro TX.” In Radio Settings, the group ensured that the Multi-Bind was enabled. Next, the group connected the RX to the cube and powered it on. The group then navigated back to the LUA Script and selected “Tracer Nano RX.” The group selected “Output Map” and made sure that Channel 1 was SBUS. No other channel was modified. Images of the Multi Bind and SBUS screens are shown below.
Binding enabled for Tracer Micro TX
SBUS Output Screen
Avionics Setup
In this section, the group 4 crew built a mock-up of the avionics as they will be installed in the Believer. Firstly, using the previous labs as a guide, the crew connected all sensors to the Cube. They were sure to test that all systems were a go. It should be noted that even though some sensors have a red or “bad” indication even though they are working. That simply means that the sensor reading is poor but the sensor is functioning. Attached is a screenshot of the Platform Health Status from GCS below.
Performance Health Status
With the FCU connected to the GCS, the group also made a table for the RC Map and Servo Function parameter sets. For the “RCMAP_X” set, there were 6 parameters, and the name and current setting were recorded. For the “SERVO#_FUNCTION” set, there were 7 active parameters, and the name and current setting were recorded. After that, the crew connected the DATX and verified connectivity in the ribbon. A picture of this can be seen below, highlighting the green heartbeat.
Ribbon Connectivity
Then, the group viewed the servo outputs in the Live Data tab (more on this in the next section). An example image of this screen is seen below. The group decided to add a table above that links the DATX control input with the Servo Outputs. For example, it lists all servo outputs that the right stick controls. Members of the group moved the controls back and forth and watched the change happen in real time on the graph below.
Servo Output Screen
Motor and Control Setup
Setting up the motor is no small task, and it was important for group 4 to fully undertsand the task at hand before engaging in hands on activity. For instance, parameters needed to be set for everything to function well in addition to the physical parts later. Two important parameters were the RC Map and Servo Function parameters. The “RCMAP_X” parameter allows the user to set up a non-standard RC input channel mapping using the RCMAP feature. It basically changes the input channel. The “SERVO#_FUNCTION” controls the aileron, rudder, elevator, and throttle. Values can be assigned to any output, and one can have multiple output channels with the same output function. It tells GC which servo moves which flight control. An image of members of group 4 working to solve problems related to this topic can be seen below.
Group 4 troubleshooting
It is also important to understand the power source for each component in a system to understand how it interlinks with other parts to make a whole. The servo functions primarily receive power from the ESC. The Motor primarily receives power from the ESC as well. The Cube and FCU receive power from the ESC and the BEC. All of these power sources to each component were found through trial and error with use of a temporary battery in lab. An image of the power in the system in question can be seen below.
Cube power setup
The setup of the motor and controls was not simple. It involved a series of steps which began with obtaining the remaining electronics to complete a set (two ESCs, two motors, and four servos). Based on the group made tables above, crew members connected one servo and one ESC to FlaperonRight and Throttle as appropriate. Instructor signoff was subsequently obtained. Before moving to the next step, group 4 tried to move the connected servo. It did not work. They then connected the ESC to the thrust stand and applied power. An image of this setup can be seen below.
Thrust stand testing
After this step, the group tried moving the servo again, this time with measureable success. Then they found the ESC Calibration Guide for the ESC in the . The group subsequently performed an ESC Calibration augmenting the manufacturer’s instructions with the following caveats: (1) the aircraft must in manual mode and be armed in GCS, and (2) with the aircraft armed, the motor can spin up. It was confirmed with instructor that Calibration was performed correctly. After this was completed, and while taking great care to be safe, the group gently ramped up the throttle to 100% to verify that the motor works. This was completed successfully.
Wiring Diagram
Using the information in the two tables above, the team wiring diagram was upgraded with the correct wiring for the Cube’s servo rail. It is important for the safety and accuracy of the missions these aircraft will be flown on that any information be up to date. This is just one small piece of the puzzle which will lead to the future success of this program. If there are future changes, these will be reflected here as well. Professor Rose does not like poorly contructed diagrams, and he dislikes people with poor planning even more. An image of his dissatisfaction with some of Group 4’s work can be seen below.
Professor's distaste for poor work
Reflection
Even though this lab and the one which preceeds it were very difficult, they were quite necessary for the furtherance of this project to excel. Without the proper setup and planning, how can one expect their equipment to perform as desired? It is important that as operators we understand this balance and apply ourselves as readily in the preparation for flight as we do for the flight itself. For a variety of reasons, these two labs were rather difficult, but even though members had to come in outside of hours, communicate late in the night, and work closely with the professor at times, new skills were learned. Part of lab activities like these ones is learning to trouble shoot difficulties, and this is as valuable a skill to have as doing the actual lab tasks themselves. To sum it up, it is my opinion that these labs have made my group members and I better UAS operators and professionals in general, and growth will increase with practice.
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