Telemetry as Instrumentation

Use telemetry as a structured debugging interface instead of random printouts.

FTC SDK FoundationsCore

In this lesson, you will:

Choose telemetry that answers a question.
Label values clearly.
Remove event-noise before competition.

Concept narrative

Telemetry is the robot's voice. It should not be a junk drawer of every variable; it should be instrumentation that answers the question the team is currently testing.

Robot mental model

For any behavior, telemetry should reveal the path from driver input to robot output. A drive bug needs axes and powers. A lift bug needs state, target, position, and output. A vision bug needs raw scores and selected result.

Implementation walkthrough

Write telemetry in groups. Use prefixes such as drive/, arm/, vision/, or auto/. During practice, print more detail. Before competition, keep the values the drive team can actually use.

StructuredTelemetry.javaJava

telemetry.addData("arm/input/a", gamepad2.a);
telemetry.addData("arm/state", armState);
telemetry.addData("arm/target ticks", targetTicks);
telemetry.addData("arm/position ticks", armMotor.getCurrentPosition());
telemetry.addData("arm/output", lastOutput);
telemetry.update();

Common mistakes and debugging

Telemetry can lie by omission. If only the output is printed, the team cannot tell whether the input, state, or target was wrong. If too many values are printed, nobody reads them under pressure.

Practice

Pick one existing mechanism and replace vague telemetry with five labeled values: input, state, target, measurement, and output.

Checkpoint

Telemetry labels identify subsystem and units.
Values answer a debugging question.
Driver-facing telemetry is not overloaded.
The test record includes the setup, prediction, and observed result.
A teammate can repeat the check from the saved evidence without guessing.

Reflection check

Check your understanding before moving on.

A lift misses its target. Which telemetry set best identifies the first wrong layer?

Only the final motor power.

Target, measured position, error, and commanded output.

The Java file name and battery color.

Why use stable telemetry keys such as arm/position ticks during repeated tests?

They make the encoder count faster.

They disable the Driver Station telemetry rate limit.

They let the team compare the same signal across runs.

0 of 2 answered

References

FIRST FTC DocsOfficial SDK, Robot Controller, and programming reference.Learn Java for FTCFTC-focused Java book and exercises by Alan G. Smith.Game Manual 0FTC community reference for programming, controls, and robot design.