Trapezoidal and Asymmetric Profiles

Use different accel/decel limits when needed.

Motion ProfilingAdvanced

In this lesson, you will:

Describe trapezoid stages.
Handle triangular profiles.
Use asymmetric constraints.

Concept narrative

A trapezoidal profile accelerates, may cruise, and decelerates. Some mechanisms need asymmetric profiles because moving up and moving down do not behave the same.

Robot mental model

Gravity, load, and friction make mechanisms asymmetric. An arm may safely accelerate upward differently than it decelerates downward.

Implementation walkthrough

Calculate whether the move reaches max velocity. If not, it becomes triangular. Choose constraints that match hardware rather than copying constants from another robot.

Constraints.javaJava

ProfileConstraints constraints = new ProfileConstraints(900, 1800, 2200);
AsymmetricMotionProfile profile = new AsymmetricMotionProfile(current, target, constraints);

Common mistakes and debugging

Bad constraints create impossible requests. If output saturates for most of the move, the profile is asking too much.

Practice

Compare a fast aggressive profile with a conservative one using telemetry only before moving the mechanism.

Checkpoint

Constraints are robot-specific.
Triangular cases are understood.
Output saturation is checked.
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 does a trapezoidal profile become triangular?

When the encoder value is negative.

When a servo is included in the hardware map.

When the move is too short to reach the configured cruise velocity.

Why might an arm use different upward and downward profile constraints?

Gravity and load can make the safe dynamics asymmetric.

FTC SDK requires one profile for each direction.

The dashboard cannot graph symmetric profiles.

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References

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