Path Constraints

Path Constraints control speed management during path execution, including maximum acceleration, top velocity and active braking power. All path constraints are configured in ForesightConfig.

Brake Aggression

brakeAggression controls how much overshoot is allowed when the robot commits to braking at the end of a segment.

A value of 1 means no bias. Values greater than 1 allow the controller to overshoot the target, while values less than 1 bias it to undershoot instead. This is useful if you don't want to brake fully. For example, if you know an obstacle or wall will help slow the robot down, you can use a higher value for faster pathing. You can also use a lower value if you don't want the robot to slam into whatever is at the target position.

The default value is 1.0. If your robot is undershooting, lower this value. Otherwise, if you are trying to optimize your path-following speed, increasing this value is a great way to speed things up.

c.brakeAggression.set(1.0);

Max Braking Power

maxBrakingPower caps how much power the robot can apply in the direction opposite its current motion. This applies any time commanded power opposes the direction of travel.

Setting this too high risks burning out the control hub but setting it too low may prevent the robot from stopping quickly enough.

The default value is 0.2.

c.maxBrakingPower.set(0.2);

Max Acceleration

maxAccelerationConstraint limits how quickly the robot's target velocity can increase per second while coasting. This only applies before the follower begins actively braking.

There is no constraint by default so the drivetrain would simply be constrained by its physical capabilities.

c.maxAccelerationConstraint.set(40.0); // inches/second^2

Max Velocity

maxVelocityConstraint caps the robot's target velocity while coasting, independent of the drivetrain's own maximum achievable speed.

There is no constraint by default so the drivetrain would simply be constrained by its physical capabilities.

c.maxVelocityConstraint.set(30.0); // inches/second

Max Deceleration

maxDecelerationConstraint limits how aggressively the robot's target velocity is allowed to decrease while coasting. This only applies before the follower begins actively braking.

There is no constraint by default which means no constraint for the robot's deceleration.

c.maxDecelerationConstraint.set(50.0); // inches/second^2

Max Deceleration Scale

maxDecelerationScale limits how quickly the robot's target velocity may decrease while coasting, as a fraction of the robot's natural deceleration.

The default value is ForesightConfig.Constraint.NONE, which disables this relative deceleration limit.

c.maxDecelerationScale.set(0.8);

When both maxDecelerationConstraint and maxDecelerationScale are enabled the lower limit is used.

Coast-down Velocity

coastDownToVelocity sets the speed that Max Deceleration slows down to instead of slowing all the way to zero.

It only works when maxDecelerationConstraint has a finite value. If it is still on default value this setting has no effect.

This is useful when you want the robot to slow down to a low speed and keep moving until the follower starts braking normally, instead of stopping too early.

The default value is 0.0, which means the robot slows down all the way to a stop.

c.coastDownToVelocity.set(0.0);

Setting Path Constraints

Path Constraints can be changed in ForesightConfig alongside the other follower constants:

public static ForesightConfig foresightConfig = new ForesightConfig(
    c -> {
        c.brakeAggression.set(1.0);
        c.maxBrakingPower.set(0.2);
        c.maxAccelerationConstraint.set(ForesightConfig.Constraint.NONE);
        c.maxVelocityConstraint.set(ForesightConfig.Constraint.NONE);
        c.maxDecelerationConstraint.set(ForesightConfig.Constraint.NONE);
        c.coastDownToVelocity.set(0.0);

        // Other Foresight constants...
    }
);