added StateSpaceElevator

StateSpaceElevator/robot.py

@@ -0,0 +1,169 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) FIRST and other WPILib contributors.
+# Open Source Software; you can modify and/or share it under the terms of
+# the WPILib BSD license file in the root directory of this project.
+#
+
+
+import wpilib
+import wpimath.estimator
+import wpimath.system
+import wpimath.trajectory
+import wpimath.units
+import wpimath.system.plant
+import wpimath.controller
+import math
+
+"""
+This is a sample program to demonstrate how to use a state-space controller to control an
+elevator.
+"""
+
+
+class MyRobot(wpilib.TimedRobot):
+    def robotInit(self):
+        self.kMotorPort = 0
+        self.kEncoderAChannel = 0
+        self.kEncoderBChannel = 1
+        self.kJoystickPort = 0
+        self.kHighGoalPosition = wpimath.units.feetToMeters(3)
+        self.kLowGoalPosition = wpimath.units.feetToMeters(0)
+
+        self.kCarriageMass = 4.5  # kilograms
+
+        # A 1.5in diameter drum has a radius of 0.75in, or 0.019in.
+
+        self.kDrumRadius = 1.5 / 2.0 * 25.4 / 1000.0
+
+        # Reduction between motors and encoder, as output over input. If the elevator spins slower than
+        # the motors, this number should be greater than one.
+
+        self.kElevatorGearing = 6.0
+
+        self.profile = wpimath.trajectory.TrapezoidProfile(
+            wpimath.trajectory.TrapezoidProfile.Constraints(
+                wpimath.units.feetToMeters(3.0),
+                wpimath.units.feetToMeters(6.0),  # Max elevator speed and acceleration.
+            )
+        )
+
+        self.lastProfiledReference = wpimath.trajectory.TrapezoidProfile.State()
+
+        # The plant holds a state-space model of our elevator. This system has the following properties:
+        #
+        # States: [position, velocity], in meters and meters per second.
+        # Inputs (what we can "put in"): [voltage], in volts.
+        # Outputs (what we can measure): [position], in meters.
+        #
+        # This elevator is driven by two NEO motors.
+
+        self.elevatorPlant = wpimath.system.LinearSystemId.elevatorSystem(
+            wpimath.system.plant.DCMotor.NEO(2),
+            self.kCarriageMass,
+            self.kDrumRadius,
+            self.kElevatorGearing,
+        )
+
+        # The observer fuses our encoder data and voltage inputs to reject noise.
+
+        self.observer = wpimath.estimator.KalmanFilter_2_1_1(
+            self.elevatorPlant,
+            (
+                wpimath.units.inchesToMeters(2),
+                wpimath.units.inchesToMeters(40),
+            ),  # How accurate we think our
+            # model is, in meters and meters/second.
+            (
+                0.001,
+            ),  # How accurate we think our encoder position data is. In this case we very
+            # highly trust our encoder position reading.
+            0.020,
+        )
+
+        # A LQR uses feedback to create voltage commands.
+
+        self.controller = wpimath.controller.LinearQuadraticRegulator_2_1(
+            self.elevatorPlant,
+            (
+                wpimath.units.inchesToMeters(1.0),
+                wpimath.units.inchesToMeters(10.0),
+            ),  # qelms. Position and velocity
+            # error tolerances, in meters and meters per second. Decrease this to more heavily penalize state excursion,
+            # or make the controller behave more aggressively. In this example we weight position much more highly than
+            # velocity, but this can be tuned to balance the two.
+            (
+                12.0,
+            ),  # relms. Control effort (voltage) tolerance. Decrease this to more heavily penalize control
+            # effort, or make the controller less aggressive. 12 is a good starting point because that is the
+            # (approximate) maximum voltage of a battery.
+            0.020,
+            # Nominal time between loops. 0.020 for TimedRobot, but can be lower if using notifiers.
+        )
+
+        # The state-space loop combines a controller, observer, feedforward and plant for easy control.
+
+        self.loop = wpimath.system.LinearSystemLoop_2_1_1(
+            self.elevatorPlant, self.controller, self.observer, 12.0, 0.020
+        )
+
+        # An encoder set up to measure elevator height in meters
+
+        self.encoder = wpilib.Encoder(self.kEncoderAChannel, self.kEncoderBChannel)
+
+        self.motor = wpilib.PWMSparkMax(self.kMotorPort)
+
+        # A joystick to read the trigger
+
+        self.joystick = wpilib.Joystick(self.kJoystickPort)
+
+        # Circumference = pi * d, so distance per click = pi * d / counts
+
+        self.encoder.setDistancePerPulse(math.pi * 2 * self.kDrumRadius / 4096.0)
+
+    def teleopInit(self):
+        # Reset our loop to make sure it's in a known state.
+
+        self.loop.reset((self.encoder.getDistance(), self.encoder.getRate()))
+
+        # Reset our last reference to the current state.
+
+        self.lastProfiledReference = wpimath.trajectory.TrapezoidProfile.State(
+            self.encoder.getDistance(), self.encoder.getRate()
+        )
+
+    def teleopPeriodic(self):
+        if self.joystick.getTrigger():
+            # the trigger is pressed, so we go to the high goal.
+
+            goal = wpimath.trajectory.TrapezoidProfile.State(
+                self.kHighGoalPosition, 0.0
+            )
+        else:
+            # Otherwise, we go to the low goal
+
+            goal = wpimath.trajectory.TrapezoidProfile.State(self.kLowGoalPosition, 0.0)
+        # Step our TrapezoidalProfile forward 20ms and set it as our next reference
+
+        self.lastProfiledReference = self.profile.calculate(0.020)
+        self.loop.setNextR(self.lastProfiledReference.position)
+
+        # Correct our Kalman filter's state vector estimate with encoder data.
+
+        self.loop.correct((self.encoder.getDistance()))
+
+        # Update our LQR to generate new voltage commands and use the voltages to predict the next state with out
+        # Kalman filter.
+
+        self.loop.predict(0.020)
+
+        # Send the new calculated voltage to the motors.
+        # voltage = duty cycle * battery voltage, so
+        # duty cycle = voltage / battery voltage
+
+        nextVoltage = self.loop.U(0)
+        self.motor.setVoltage(nextVoltage)
+
+
+if __name__ == "__main__":
+    wpilib.run(MyRobot)

run_tests.sh

@@ -44,6 +44,7 @@ BASE_TESTS="
   ShuffleBoard
   Solenoid
   StatefulAutonomous
+  StateSpaceElevator
   StateSpaceFlywheel
   StateSpaceFlywheelSysId
   SwerveBot