libstp.step.servo.steps

Classes

SetServoPosition

Set a servo to a target angle and optionally wait for the move to finish.

ShakeServo

Oscillate a servo between two angles for a fixed amount of time.

EaseServo

Move a servo to a target angle with ease-in/ease-out timing.

FullyDisableServos

Fully disable all servo outputs, removing all power.

Functions

servo(→ SetServoPosition)

Set a servo to a specific angle and wait for the move to finish.

shake_servo(→ ShakeServo)

Oscillate a servo back and forth between two angles for a set time.

slow_servo(→ EaseServo)

Move a servo to an angle with smooth ease-in/ease-out motion.

fully_disable_servos(→ FullyDisableServos)

Fully disable all servo outputs, removing all power from the servo pins.

Module Contents

class libstp.step.servo.steps.SetServoPosition(servo: libstp.hal.Servo, target_angle: float, duration: float | None = None)

Bases: libstp.step.Step

Set a servo to a target angle and optionally wait for the move to finish.

libstp.step.servo.steps.servo(servo: libstp.hal.Servo, angle: float) → SetServoPosition

Set a servo to a specific angle and wait for the move to finish.

Commands the servo to the requested angle, then sleeps for an estimated duration based on the angular distance the servo needs to travel and its approximate speed. This ensures subsequent steps do not begin until the servo has physically reached its target.

The valid angle range is 0 to 170 degrees.

Parameters:

  • servo – The servo to control, obtained from the robot hardware map (e.g. robot.servo(0)).

  • angle – Target angle in degrees, from 0.0 to 170.0.

Returns:

A SetServoPosition step with automatically estimated wait duration.

Example:

from libstp.step.servo import servo

# Open a claw by moving servo 0 to 90 degrees
servo(robot.servo(0), 90.0)

# Close the claw, then raise the arm
sequence(
    servo(robot.servo(0), 10.0),
    motor_move_to(robot.motor(2), position=400),
)
class libstp.step.servo.steps.ShakeServo(servo: libstp.hal.Servo, duration: float, angle_a: float, angle_b: float)

Bases: libstp.step.Step

Oscillate a servo between two angles for a fixed amount of time.

libstp.step.servo.steps.shake_servo(servo: libstp.hal.Servo, duration: float, angle_a: float, angle_b: float) → ShakeServo

Oscillate a servo back and forth between two angles for a set time.

Rapidly alternates the servo between angle_a and angle_b for the given duration. The dwell time at each angle is automatically estimated from the angular distance so the servo has time to physically reach each endpoint before reversing. Useful for shaking objects loose or signalling the operator.

The valid angle range is 0 to 170 degrees.

Parameters:

  • servo – The servo to control, obtained from the robot hardware map (e.g. robot.servo(1)).

  • duration – Total oscillation time in seconds. Must be >= 0.

  • angle_a – First oscillation endpoint in degrees (0.0 – 170.0).

  • angle_b – Second oscillation endpoint in degrees (0.0 – 170.0).

Returns:

A ShakeServo step ready to be scheduled in a step sequence.

Example:

from libstp.step.servo import shake_servo

# Shake a sorting tray for 3 seconds between 60 and 120 degrees
shake_servo(robot.servo(1), duration=3.0, angle_a=60.0, angle_b=120.0)
class libstp.step.servo.steps.EaseServo(servo: libstp.hal.Servo, target_angle: float, speed: float)

Bases: libstp.step.Step

Move a servo to a target angle with ease-in/ease-out timing.

libstp.step.servo.steps.slow_servo(servo: libstp.hal.Servo, angle: float, speed: float = 60.0) → EaseServo

Move a servo to an angle with smooth ease-in/ease-out motion.

Instead of commanding the servo to jump straight to the target (as servo() does), this step interpolates through intermediate positions using a smoothstep curve (3t^2 - 2t^3). The result is a gentle acceleration and deceleration that avoids mechanical shock and reduces jerk on the mechanism.

The total move duration is derived from the angular distance divided by speed. Intermediate positions are updated at ~10 Hz.

The valid angle range is 0 to 170 degrees.

Parameters:

  • servo – The servo to control, obtained from the robot hardware map (e.g. robot.servo(0)).

  • angle – Target angle in degrees (0.0 – 170.0).

  • speed – Movement speed in degrees per second. Must be positive. Defaults to 60.0 deg/s, which moves the full range in about 2.8 seconds.

Returns:

An EaseServo step ready to be scheduled in a step sequence.

Example:

from libstp.step.servo import slow_servo

# Gently lower the arm servo to 20 degrees at 45 deg/s
slow_servo(robot.servo(0), angle=20.0, speed=45.0)

# Use default speed for a smooth open
slow_servo(robot.servo(0), angle=150.0)
class libstp.step.servo.steps.FullyDisableServos

Bases: libstp.step.Step

Fully disable all servo outputs, removing all power.

libstp.step.servo.steps.fully_disable_servos() → FullyDisableServos

Fully disable all servo outputs, removing all power from the servo pins.

Commands the firmware to enter the fully-disabled servo mode for every servo port. In this mode, no PWM signal is sent and the servos can be moved freely by hand. This is useful for saving power or when the servos should not hold position (e.g. at the end of a run).

Servos will automatically re-enable when a new position command is sent (e.g. via servo() or slow_servo()).

Returns:

A FullyDisableServos step.

Example:

from libstp.step.servo import fully_disable_servos

# Release all servos at the end of a mission
fully_disable_servos()