Implementing a Profiled Mechanism

Profile plus feedback in a subsystem.

Motion ProfilingAdvanced

In this lesson, you will:

Regenerate only on target changes.
Follow profile state.
Hold safely at the end.

Concept narrative

A profiled mechanism uses the profile as a moving target and PID/PIDF as the follower. The profile decides where the mechanism should be; feedback decides how hard to push.

Robot mental model

The subsystem owns the profile, timer, previous target, current target, and output. The OpMode only asks for named states.

Implementation walkthrough

When target changes, build a profile from current position to target and reset timer. Each loop, calculate current profile state and control toward it.

ProfiledMechanism.javaJava

if (target != previousTarget) {
    profile = new AsymmetricMotionProfile(currentPosition, target, constraints);
    timer.reset();
    previousTarget = target;
}
ProfileState state = profile.calculate(timer.seconds());

Common mistakes and debugging

If the profile is rebuilt every loop, motion never progresses. If hold behavior is poor, tune travel and holding separately.

Practice

Build a profiled lift or arm subsystem with telemetry for target, actual, velocity, error, and output.

Checkpoint

Profile resets only on target changes.
Telemetry shows profile and actual.
Hold behavior is safe.
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.

When should a profiled subsystem create a new motion profile?

On every control-loop iteration.

When its target changes, using the current measured position as the new start.

Only after a competition match ends.

What is the correct role split between a profile and PID/PIDF feedback?

The profile reads encoders while PID selects gamepad buttons.

PID replaces the profile after the first loop.

The profile supplies the moving target; feedback corrects the actual mechanism toward it.

0 of 2 answered

References

Game Manual 0FTC community reference for programming, controls, and robot design.FTC DashboardLive telemetry, graphs, config variables, and camera streaming.