Explore

Lab 11 - Motors and Controls

Objective

Avionics simulation, DATX calibration, control mapping, servo/motor setup, ESC calibration, and wiring documentation.

Overview

The purpose of this lab was to simulate key avionics and control functions for the Believer aircraft, including powering, arming, sensor integration, servo mapping, motor control, and ESC calibration. This lab focused on ensuring correct setup and calibration of the DATX transmitter, verifying input and output mappings, and adjusting parameters.

We assembled a mock-up of the avionics by connecting sensors to the Cube, checking system health, and mapping DATX inputs to servo outputs. Additionally, motors, ESCs, and servos were connected and tested. ESCs were calibrated according to the manufacturer’s procedure, followed by a throttle ramp-up test.

Resources Used

ArduPilot Parameters

Servo Reference

ESC Model & Calibration Guide

Motor Model

TX/RX Model

Cube Wiring Quick Start Guide

Servo Functions

ArduPilot Overview

Parameter and Mapping

Parameter and Mapping

Name

Current Setting

Column 3

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

Open

RCMAP_FLAP

Open

RCMAP_PITCH

Open

RCMAP_ROLL

Open

RCMAP_THROTTLE

Open

RCMAP_YAW

Open

There are no rows in this table

⁠

Table

Table

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

Questions

1. What is CRSF and SBUS? What are the differences? CRSF is a full-duplex digital protocol that supports telemetry, fast update rates, and two-way communication. SBUS is a one-wire serial protocol used for sending RC control signals only. CRSF uses four wires, is faster, and supports integrated telemetry. SBUS uses one wire and is slower, with no full duplex capability.

2. What is Multi-Bind on the TBS Tracer? Multi-Bind allows a single transmitter to stay paired with multiple receivers, enabling quick switching between aircraft without re-binding.

DATX Calibration Tasks

Powered on the DATX.

Observed stick positions before calibration.

Navigated to the Hardware menu and performed stick calibration.

Verified correct calibration by moving sticks and confirming accurate on-screen indicators.

Opened LUA Script → Tracer Micro TX.

Ensured Multi-Bind = Enabled.

Connected RX to the Cube and powered it on.

Opened LUA Script → Selected Tracer Nano RX.

Entered Output Map and changed Channel 1 = SBUS (no other changes).

Avionics Setup

Tasks Completed:

Connected all sensors to the Cube, including GPS, airspeed, telemetry, and other avionics.

Verified all systems were green through GCS.

Recorded platform health (screenshot included in final submission).

Documented full RCMAP_X and SERVO#_FUNCTION tables.

Connected DATX and verified RC connectivity via ribbon indicator.

Viewed servo outputs in Live Data tab.

Completed DATX Input → Servo Output mapping table (see above).

Motors & Control Setup

Questions

1. What does the RCMAP_X parameter control? RCMAP_X parameters remap non-standard RC input channels to match the expected ArduPilot configuration. They determine which input channel corresponds to throttle, roll, pitch, yaw, brakes, and flaps.

2. What does the SERVO#_FUNCTION control? SERVO#_FUNCTION assigns each servo output to a specific aircraft function (flaperon, elevator, rudder, throttle, etc.). Multiple servo channels can share the same function.

3. List all possible power sources for the following systems:

Servo: ESC BEC

Motor: ESC

Cube/FCU: ESC BEC or dedicated BEC

Motor/ESC Tasks

Retrieved remaining electronics: 2 ESCs, 2 motors, 4 servos.

Connected one servo and one ESC to FlaperonRight and Throttle outputs.

Instructor signature received.

Tested servo movement before ESC connection: Servo did not work (no power).

Connected ESC to thrust stand and applied power.

Tested servo again: Servo now works (power supplied via ESC/BEC).

Performed ESC calibration following manufacturer’s guide with added requirements:

Aircraft in Manual Mode

Aircraft armed in GCS

Instructor confirmed calibration success.

Performed controlled throttle ramp-up to verify motor function.

Wiring Diagram

Using updated RCMAP_X and SERVO#_FUNCTION tables, the team wiring diagram was updated to reflect correct Cube servo rail assignments, sensor routing, and ESC/motor wiring. This includes identification of:

Servo channel positions

Power distribution

SBUS input path

ESC signal and power paths

Correct mapping for flaperons, V-tail, rudder, and throttle

Overall Reflection:

Throughout Lab 11, the primary focus was on developing a complete understanding of how the avionics, controls, motors, and power systems integrate within the Believer UAS platform. This involved modifying and calibrating the DATX transmitter, correctly wiring and powering the ESCs and motors, and performing a full ESC calibration to ensure safe and predictable motor behavior. Together, these steps strengthened my understanding of how control inputs travel from the pilot’s transmitter to physical movement in the aircraft’s control surfaces and propulsion system.

The most important modification made to the DATX was the calibration and protocol mapping within the LUA script. By calibrating the sticks under the hardware menu to ensure that the DATX correctly interpreted all control inputs we will avoid the fact that even small errors or offsets in stick position could translate to unintended control movements in the aircraft. Also that Multi-Bind was enabled, allowing the same transmitter to stay paired with multiple receivers. This feature is essential in a multi-aircraft lab environment because it prevents the need to constantly re-bind every time a new platform is tested.

Another significant change was modifying the Output Map on the Tracer Nano RX so that Channel 1 was set to SBUS. This ensured that the Cube received all RC inputs on the correct digital protocol. If Channel 1 was not set to SBUS, the Cube would not interpret the control signals, resulting in no servo or motor response. These DATX modifications were necessary to establish a clean, stable control link between the transmitter and flight controller, which is the foundation for every other system in the aircraft.

In the Believer circuit, the ESC serves as the bridge between the power system, flight controller, and the motor. The ESC is powered directly by the main battery, and in turn, the ESC provides regulated power to the Cube’s servo rail via its built-in BEC (Battery Eliminator Circuit). That is why, before the ESC was connected and powered, my servo did not work, there was no power source feeding the servo rail. Once the ESC was plugged into the battery and signal wire, the servo immediately came to life because it finally had a power supply.

The ESC signal wire must be connected to the Throttle output channel on the Cube. This channel sends a signal to the ESC telling it how fast to spin the motor. The ESC then distributes the appropriate power to the motor, converting DC battery power. Understanding this chain from battery → ESC → motor → thrust, makes it clear why power distribution and correct wiring are essential for a safe and functioning aircraft.

The key action performed on the ESC was a full ESC calibration, which synchronizes the ESC to the transmitter’s throttle range. Without calibration, the ESC may misinterpret the throttle signal, leading to unpredictable motor behavior such as delayed start, unexpected RPM jumps, or a lack of full power.

Lab 11 tied together the major systems that make the Believer operational: radio control, servo actuation, sensor integration, and propulsion. By modifying the DATX, mapping controls, powering and wiring the ESCs, and performing calibration, I gained a deeper understanding of how each component depends on the next. These skills are essential not only for building a reliable aircraft but also for safe operation, accurate troubleshooting, and future autonomous integration.

Photos!

⁠

Want to print your doc?
This is not the way.

Try clicking the ··· in the right corner or using a keyboard shortcut (

CtrlP

) instead.