05 / From Timed Steps to Actions

Actions and Sequencing

Use reusable action-style tasks to prepare for Road Runner 1.0 autonomous.

75 minAdvancedFrom Timed Steps to Actions

You will

01Describe the Road Runner action mental model.
02Write a reusable action for a mechanism.
03Compose movement and mechanism work into a routine.

Why Actions and Sequencing matters

This lesson is about sequencing decisions without a human driver. Autonomous code must know where it starts, what it is trying to accomplish, how each step ends, and what safe behavior happens when a step fails.

Starting point

Actions are reusable autonomous behaviors

Road Runner 1.0 leans heavily on actions: small tasks that keep running until they report completion. This matches command-based thinking and makes autonomous routines easier to compose.

Composition is the payoff

Once mechanisms expose actions, an autonomous routine can drive, move an arm, wait, and deposit without duplicating mechanism details in every auto file.

Build path

Teach autonomous as a progression from timed steps to encoder checks to state machines and actions. Each layer should preserve the same core habits: explicit state, telemetry for the active step, timeout or finish condition, and a final safe stop.

For this specific lesson, students should first restate the goal in robot terms, then identify the value or behavior they expect to observe, then run the smallest test that proves the idea. The lesson should feel like a guided lab: predict, run, observe, explain, and only then extend.

MechanismAction.java · Java

public Action closeClawAction() {
    return packet -> {
        clawServo.setPosition(CLOSED);
        packet.put("claw", "closed");
        return false;
    };
}

public Action waitForLiftAction(int target) {
    return packet -> {
        lift.setTargetPosition(target);
        packet.put("lift error", target - lift.getCurrentPosition());
        return Math.abs(target - lift.getCurrentPosition()) > 25;
    };
}

Debugging and failure modes

Autonomous failures are easier to diagnose when the robot reports why it moved on or stopped. Print the selected branch, active state, elapsed time, target, measurement, and stop reason. If those values are missing, the team is debugging a story with half the pages torn out.

Checks

Each action owns one behavior.
The action reports useful telemetry packet values.
The action returns false only when finished.

Check your understanding

Module check

In Road Runner action style, what does returning false mean?

0 of 1 answered

References

Road Runner 1.0 DocsRoad Runner 1.0 installation, tuning, actions, and trajectory reference.FIRST FTC DocsOfficial FTC SDK and robot programming documentation.