Designed a velocity controller for the series elastic intake.
It's stable! This gives us a place to start for controlling it.
We'll have to try it in real life at some point to see if it's right.
Change-Id: I09381b7cba42084f9d5052f54197616fd9dd8c2c
diff --git a/frc971/control_loops/python/control_loop.py b/frc971/control_loops/python/control_loop.py
index c2fe755..82d138a 100644
--- a/frc971/control_loops/python/control_loop.py
+++ b/frc971/control_loops/python/control_loop.py
@@ -291,8 +291,13 @@
def CorrectObserver(self, U):
"""Runs the correct step of the observer update."""
- self.X_hat += numpy.linalg.inv(self.A) * self.L * (
- self.Y - self.C * self.X_hat - self.D * U)
+ # See if the KalmanGain exists. That lets us avoid inverting A.
+ # Otherwise, do the inversion.
+ if hasattr(self, 'KalmanGain'):
+ KalmanGain = self.KalmanGain
+ else:
+ KalmanGain = numpy.linalg.inv(self.A) * self.L
+ self.X_hat += KalmanGain * (self.Y - self.C * self.X_hat - self.D * U)
def UpdateObserver(self, U):
"""Updates the observer given the provided U."""
@@ -511,3 +516,22 @@
self.Kv = (self.free_speed / (12.0 - self.resistance * self.free_current))
# Torque constant
self.Kt = self.stall_torque / self.stall_current
+
+
+class BAG(object):
+ # BAG motor specs available at http://motors.vex.com/vexpro-motors/bag-motor
+ def __init__(self):
+ # Stall Torque in (N m)
+ self.stall_torque = 0.43
+ # Stall Current in (Amps)
+ self.stall_current = 53.0
+ # Free Speed in (rad/s)
+ self.free_speed = 13180.0 / 60.0 * 2.0 * numpy.pi
+ # Free Current in (Amps)
+ self.free_current = 1.8
+ # Resistance of the motor (Ohms)
+ self.resistance = 12.0 / self.stall_current
+ # Motor velocity constant (radians / (sec * volt))
+ self.Kv = (self.free_speed / (12.0 - self.resistance * self.free_current))
+ # Torque constant (N * m / A)
+ self.Kt = self.stall_torque / self.stall_current
diff --git a/y2018/control_loops/python/BUILD b/y2018/control_loops/python/BUILD
index 04a244e..042c39e 100644
--- a/y2018/control_loops/python/BUILD
+++ b/y2018/control_loops/python/BUILD
@@ -56,3 +56,16 @@
],
restricted_to = ['//tools:k8'],
)
+
+py_binary(
+ name = 'intake',
+ srcs = [
+ 'intake.py',
+ ],
+ deps = [
+ '//external:python-gflags',
+ '//external:python-glog',
+ '//frc971/control_loops/python:controls',
+ ],
+ restricted_to = ['//tools:k8'],
+)
diff --git a/y2018/control_loops/python/intake.py b/y2018/control_loops/python/intake.py
index d75d438..200eb64 100755
--- a/y2018/control_loops/python/intake.py
+++ b/y2018/control_loops/python/intake.py
@@ -1,245 +1,364 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# This code was used to select the gear ratio for the intake.
-# Run it from the command line and it displays the time required
-# to rotate the intake 180 degrees.
-#
-# Michael Schuh
-# January 20, 2018
-
-import math
+from frc971.control_loops.python import control_loop
+from frc971.control_loops.python import controls
import numpy
-import scipy.integrate
+import sys
+import matplotlib
+from matplotlib import pylab
+import gflags
+import glog
-# apt-get install python-scipy python3-scipy python-numpy python3-numpy
+FLAGS = gflags.FLAGS
-pi = math.pi
-pi2 = 2.0*pi
-rad_to_deg = 180.0/pi
-inches_to_meters = 0.0254
-lbs_to_kg = 1.0/2.2
-newton_to_lbf = 0.224809
-newton_meters_to_ft_lbs = 0.73756
-run_count = 0
-theta_travel = 0.0
+try:
+ gflags.DEFINE_bool('plot', False, 'If true, plot the loop response.')
+except gflags.DuplicateFlagError:
+ pass
-def to_deg(angle):
- return (angle*rad_to_deg)
+class Intake(control_loop.ControlLoop):
+ def __init__(self, name="Intake"):
+ super(Intake, self).__init__(name)
+ self.motor = control_loop.BAG()
+ # TODO(constants): Update all of these & retune poles.
+ # Stall Torque in N m
+ self.stall_torque = self.motor.stall_torque
+ # Stall Current in Amps
+ self.stall_current = self.motor.stall_current
+ # Free Speed in RPM
+ self.free_speed = self.motor.free_speed
+ # Free Current in Amps
+ self.free_current = self.motor.free_current
-def to_rad(angle):
- return (angle/rad_to_deg)
+ # Resistance of the motor
+ self.resistance = self.motor.resistance
+ # Motor velocity constant
+ self.Kv = self.motor.Kv
+ # Torque constant
+ self.Kt = self.motor.Kt
+ # Gear ratio
+ self.G = 1.0 / 100.0
-def to_rotations(angle):
- return (angle/pi2)
+ self.motor_inertia = 0.000006
-def time_derivative(x, t, voltage, c1, c2, c3):
- global run_count
- theta, omega = x
- dxdt = [omega, -c1*omega + c3*math.sin(theta) + c2*voltage]
- run_count = run_count + 1
+ # Series elastic moment of inertia
+ self.Je = self.motor_inertia / (self.G * self.G)
+ # Grabber moment of inertia
+ self.Jo = 0.295
- #print ('dxdt = ',dxdt,' repr(dxdt) = ', repr(dxdt))
- return dxdt
+ # Spring constant (N m / radian)
+ self.Ks = 30.0
-def get_distal_angle(theta_proximal):
- # For the proximal angle = -50 degrees, the distal angle is -180 degrees
- # For the proximal angle = 10 degrees, the distal angle is -90 degrees
- distal_angle = to_rad(-180.0 - (-50.0-to_deg(theta_proximal))*(180.0-90.0)/(50.0+10.0))
- return distal_angle
-
+ # Control loop time step
+ self.dt = 0.00505
-def get_180_degree_time(c1,c2,c3,voltage,gear_ratio,motor_free_speed):
- #print ("# step time theta angular_speed angular_acceleration theta angular_speed motor_speed motor_speed_fraction")
- #print ("# (sec) (rad) (rad/sec) (rad/sec^2) (rotations) (rotations/sec) (rpm) (fraction)")
- global run_count
- global theta_travel
+ # State is [output_position, output_velocity,
+ # elastic_position, elastic_velocity]
+ # The output position is the absolute position of the intake arm.
+ # The elastic position is the absolute position of the motor side of the
+ # series elastic.
+ # Input is [voltage]
- if ( True ):
- # Gravity is assisting the motion.
- theta_start = 0.0
- theta_target = pi
- elif ( False ):
- # Gravity is assisting the motion.
- theta_start = 0.0
- theta_target = -pi
- elif ( False ):
- # Gravity is slowing the motion.
- theta_start = pi
- theta_target = 0.0
- elif ( False ):
- # Gravity is slowing the motion.
- theta_start = -pi
- theta_target = 0.0
- elif ( False ):
- # This is for the proximal arm motion.
- theta_start = to_rad(-50.0)
- theta_target = to_rad(10.0)
+ self.A_continuous = numpy.matrix(
+ [[0.0, 1.0, 0.0, 0.0],
+ [(-self.Ks / self.Jo), 0.0, (self.Ks / self.Jo), 0.0],
+ [0.0, 0.0, 0.0, 1.0],
+ [(self.Ks / self.Je), 0.0, (-self.Ks / self.Je), \
+ -self.Kt / (self.Je * self.resistance * self.Kv * self.G * self.G)]])
- theta_half = 0.5*(theta_start + theta_target)
- if (theta_start > theta_target):
- voltage = -voltage
- theta = theta_start
- theta_travel = theta_start - theta_target
- if ( run_count == 0 ):
- print ("# Theta Start = %.2f radians End = %.2f Theta travel %.2f Theta half = %.2f Voltage = %.2f" % (theta_start,theta_target,theta_travel,theta_half, voltage))
- print ("# Theta Start = %.2f degrees End = %.2f Theta travel %.2f Theta half = %.2f Voltage = %.2f" % (to_deg(theta_start),to_deg(theta_target),to_deg(theta_travel),to_deg(theta_half), voltage))
- omega = 0.0
- time = 0.0
- delta_time = 0.01 # time step in seconds
- for step in range(1, 5000):
- t = numpy.array([time, time + delta_time])
- time = time + delta_time
- x = [theta, omega]
- angular_acceleration = -c1*omega + c2*voltage
- x_n_plus_1 = scipy.integrate.odeint(time_derivative,x,t,args=(voltage,c1,c2,c3))
- #print ('x_n_plus_1 = ',x_n_plus_1)
- #print ('repr(x_n_plus_1) = ',repr(x_n_plus_1))
- theta, omega = x_n_plus_1[1]
- #theta= x_n_plus_1[0]
- #omega = x_n_plus_1[1]
- if ( False ):
- print ("%4d %8.4f %8.2f %8.4f %8.4f %8.3f %8.3f %8.3f %8.3f" % \
- (step, time, theta, omega, angular_acceleration, to_rotations(theta), \
- to_rotations(omega), omega*gear_ratio*60.0/pi2, omega*gear_ratio/motor_free_speed ))
- if (theta_start < theta_target):
- # Angle is increasing through the motion.
- if (theta > theta_half):
- break
- else:
- # Angle is decreasing through the motion.
- if (theta < theta_half):
- break
-
- #print ("# step time theta angular_speed angular_acceleration theta angular_speed motor_speed motor_speed_fraction")
- #print ("# (sec) (rad) (rad/sec) (rad/sec^2) (rotations) (rotations/sec) (rpm) (fraction)")
- #print ("# Total time for 1/2 rotation of arm is %0.2f" % (time*2))
- return (2.0*time)
+ # Start with the unmodified input
+ self.B_continuous = numpy.matrix(
+ [[0.0],
+ [0.0],
+ [0.0],
+ [self.Kt / (self.G * self.Je * self.resistance)]])
-def main():
- gravity = 9.8 # m/sec^2 Gravity Constant
- gravity = 0.0 # m/sec^2 Gravity Constant - Use 0.0 for the intake. It is horizontal.
- voltage_nominal = 12 # Volts
-
- # Vex 775 Pro motor specs from http://banebots.com/p/M2-RS550-120
- motor_name = "Vex 775 Pro motor specs from http://banebots.com/p/M2-RS550-120"
- current_stall = 134 # amps stall current
- current_no_load = 0.7 # amps no load current
- torque_stall = 710/1000.0 # N-m Stall Torque
- speed_no_load_rpm = 18730 # RPM no load speed
-
- if ( True ):
- # Bag motor from https://www.vexrobotics.com/217-3351.html
- motor_name = "Bag motor from https://www.vexrobotics.com/217-3351.html"
- current_stall = 53.0 # amps stall current
- current_no_load = 1.8 # amps no load current
- torque_stall = 0.4 # N-m Stall Torque
- speed_no_load_rpm = 13180.0 # RPM no load speed
-
- if ( False ):
- # Mini CIM motor from https://www.vexrobotics.com/217-3371.html
- motor_name = "Mini CIM motor from https://www.vexrobotics.com/217-3371.html"
- current_stall = 89.0 # amps stall current
- current_no_load = 3.0 # amps no load current
- torque_stall = 1.4 # N-m Stall Torque
- speed_no_load_rpm = 5840.0 # RPM no load speed
+ self.C = numpy.matrix([[1.0, 0.0, -1.0, 0.0],
+ [0.0, 0.0, 1.0, 0.0]])
+ self.D = numpy.matrix([[0.0],
+ [0.0]])
- # How many motors are we using?
- num_motors = 1
+ self.A, self.B = self.ContinuousToDiscrete(
+ self.A_continuous, self.B_continuous, self.dt)
- # Motor values
- print ("# Motor: %s" % (motor_name))
- print ("# Number of motors: %d" % (num_motors))
- print ("# Stall torque: %.1f n-m" % (torque_stall))
- print ("# Stall current: %.1f amps" % (current_stall))
- print ("# No load current: %.1f amps" % (current_no_load))
- print ("# No load speed: %.0f rpm" % (speed_no_load_rpm))
-
- # Constants from motor values
- resistance_motor = voltage_nominal/current_stall
- speed_no_load_rps = speed_no_load_rpm/60.0 # Revolutions per second no load speed
- speed_no_load = speed_no_load_rps*2.0*pi
- Kt = num_motors*torque_stall/current_stall # N-m/A torque constant
- Kv_rpm = speed_no_load_rpm /(voltage_nominal - resistance_motor*current_no_load) # rpm/V
- Kv = Kv_rpm*2.0*pi/60.0 # rpm/V
-
- # Robot Geometry and physics
- length_proximal_arm = inches_to_meters*47.34 # m Length of arm connected to the robot base
- length_distal_arm = inches_to_meters*44.0 # m Length of arm that holds the cube
- length_intake_arm = inches_to_meters*9.0 # m Length of intake arm from the pivot point to where the big roller contacts a cube.
- mass_cube = 6.0*lbs_to_kg # Weight of the cube in Kgrams
- mass_proximal_arm = 5.5*lbs_to_kg # Weight of proximal arm
- mass_distal_arm = 3.5*lbs_to_kg # Weight of distal arm
- mass_distal = mass_cube + mass_distal_arm
- mass_proximal = mass_proximal_arm + mass_distal
- radius_to_proximal_arm_cg = 22.0*inches_to_meters # m Length from arm pivot point to arm CG
- radius_to_distal_arm_cg = 10.0*inches_to_meters # m Length from arm pivot point to arm CG
+ controllability = controls.ctrb(self.A, self.B)
+ glog.debug('ctrb: ' + repr(numpy.linalg.matrix_rank(controllability)))
- radius_to_distal_cg = ( length_distal_arm*mass_cube + radius_to_distal_arm_cg*mass_distal_arm)/mass_distal
- radius_to_proximal_cg = ( length_proximal_arm*mass_distal + radius_to_proximal_arm_cg*mass_proximal_arm)/mass_proximal
- J_cube = length_distal_arm*length_distal_arm*mass_cube
- # Kg m^2 Moment of inertia of the proximal arm
- J_proximal_arm = radius_to_proximal_arm_cg*radius_to_proximal_arm_cg*mass_distal_arm
- # Kg m^2 Moment of inertia distal arm and cube at end of proximal arm.
- J_distal_arm_and_cube_at_end_of_proximal_arm = length_proximal_arm*length_proximal_arm*mass_distal
- J_distal_arm = radius_to_distal_arm_cg*radius_to_distal_arm_cg*mass_distal_arm # Kg m^2 Moment of inertia of the distal arm
- J = J_distal_arm_and_cube_at_end_of_proximal_arm + J_proximal_arm # Moment of inertia of the arm with the cube on the end
- # Intake claw
- J_intake = 0.295 # Kg m^2 Moment of inertia of intake
- J = J_intake
+ observability = controls.ctrb(self.A.T, self.C.T)
+ glog.debug('obs: ' + repr(numpy.linalg.matrix_rank(observability)))
- gear_ratio = 140.0 # Guess at the gear ratio
- gear_ratio = 100.0 # Guess at the gear ratio
- gear_ratio = 90.0 # Guess at the gear ratio
+ glog.debug('A_continuous ' + repr(self.A_continuous))
+ glog.debug('B_continuous ' + repr(self.B_continuous))
- error_margine = 1.0
- voltage = 10.0 # voltage for the motor. Assuming a loaded robot so not using 12 V.
- # It might make sense to use a lower motor frees peed when the voltage is not a full 12 Volts.
- # motor_free_speed = Kv*voltage
- motor_free_speed = speed_no_load
-
- print ("# Kt = %f N-m/A\n# Kv_rpm = %f rpm/V\n# Kv = %f radians/V" % (Kt, Kv_rpm, Kv))
- print ("# %.2f Ohms Resistance of the motor " % (resistance_motor))
- print ("# %.2f kg Cube weight" % (mass_cube))
- print ("# %.2f kg Proximal Arm mass" % (mass_proximal_arm))
- print ("# %.2f kg Distal Arm mass" % (mass_distal_arm))
- print ("# %.2f kg Distal Arm and Cube weight" % (mass_distal))
- print ("# %.2f m Length from distal arm pivot point to arm CG" % (radius_to_distal_arm_cg))
- print ("# %.2f m Length from distal arm pivot point to arm and cube cg" % (radius_to_distal_cg))
- print ("# %.2f kg-m^2 Moment of inertia of the cube about the arm pivot point" % (J_cube))
- print ("# %.2f m Length from proximal arm pivot point to arm CG" % (radius_to_proximal_arm_cg))
- print ("# %.2f m Length from proximal arm pivot point to arm and cube cg" % (radius_to_proximal_cg))
- print ("# %.2f m Proximal arm length" % (length_proximal_arm))
- print ("# %.2f m Distal arm length" % (length_distal_arm))
+ self.K = numpy.matrix(numpy.zeros((1, 4)))
- print ("# %.2f kg-m^2 Moment of inertia of the intake about the intake pivot point" % (J_intake))
- print ("# %.2f kg-m^2 Moment of inertia of the distal arm about the arm pivot point" % (J_distal_arm))
- print ("# %.2f kg-m^2 Moment of inertia of the proximal arm about the arm pivot point" % (J_proximal_arm))
- print ("# %.2f kg-m^2 Moment of inertia of the distal arm and cube mass about the proximal arm pivot point" % (J_distal_arm_and_cube_at_end_of_proximal_arm))
- print ("# %.2f kg-m^2 Moment of inertia of the intake the intake pivot point (J value used in simulation)" % (J))
- print ("# %d Number of motors" % (num_motors))
-
- print ("# %.2f V Motor voltage" % (voltage))
- for gear_ratio in range(60, 241, 10):
- c1 = Kt*gear_ratio*gear_ratio/(Kv*resistance_motor*J)
- c2 = gear_ratio*Kt/(J*resistance_motor)
- c3 = radius_to_proximal_cg*mass_proximal*gravity/J
-
- if ( False ):
- print ("# %.8f 1/sec C1 constant" % (c1))
- print ("# %.2f 1/sec C2 constant" % (c2))
- print ("# %.2f 1/(V sec^2) C3 constant" % (c3))
- print ("# %.2f RPM Free speed at motor voltage" % (voltage*Kv_rpm))
-
- torque_90_degrees = radius_to_distal_cg*mass_distal*gravity
- voltage_90_degrees = resistance_motor*torque_90_degrees/(gear_ratio*Kt)
- torque_peak = gear_ratio*num_motors*torque_stall
- torque_peak_ft_lbs = torque_peak * newton_meters_to_ft_lbs
- normal_force = torque_peak/length_intake_arm
- normal_force_lbf = newton_to_lbf*normal_force
- time_required = get_180_degree_time(c1,c2,c3,voltage,gear_ratio,motor_free_speed)
- print ("Time for %.1f degrees for gear ratio %3.0f is %.2f seconds. Peak (stall) torque %3.0f nm %3.0f ft-lb Normal force at intake end %3.0f N %2.0f lbf" % \
- (to_deg(theta_travel),gear_ratio,time_required,
- torque_peak,torque_peak_ft_lbs,normal_force,normal_force_lbf))
-
+ q_pos = 0.05
+ q_vel = 2.65
+ self.Q = numpy.matrix(numpy.diag([(q_pos ** 2.0), (q_vel ** 2.0),
+ (q_pos ** 2.0), (q_vel ** 2.0)]))
+
+ r_nm = 0.025
+ self.R = numpy.matrix(numpy.diag([(r_nm ** 2.0), (r_nm ** 2.0)]))
+
+ self.KalmanGain, self.Q_steady = controls.kalman(
+ A=self.A, B=self.B, C=self.C, Q=self.Q, R=self.R)
+
+ self.L = self.A * self.KalmanGain
+
+ # The box formed by U_min and U_max must encompass all possible values,
+ # or else Austin's code gets angry.
+ self.U_max = numpy.matrix([[12.0]])
+ self.U_min = numpy.matrix([[-12.0]])
+
+ self.Kff = controls.TwoStateFeedForwards(self.B, self.Q)
+
+ self.InitializeState()
+
+
+class DelayedIntake(Intake):
+ def __init__(self, name="DelayedIntake"):
+ super(DelayedIntake, self).__init__(name=name)
+
+ self.A_undelayed = self.A
+ self.B_undelayed = self.B
+
+ self.C_unaugmented = self.C
+ self.C = numpy.matrix(numpy.zeros((2, 5)))
+ self.C[0:2, 0:4] = self.C_unaugmented
+
+ # Model this as X[4] is the last power. And then B applies to the last
+ # power. This lets us model the 1 cycle PWM delay accurately.
+ self.A = numpy.matrix(numpy.zeros((5, 5)))
+ self.A[0:4, 0:4] = self.A_undelayed
+ self.A[0:4, 4] = self.B_undelayed
+ self.B = numpy.matrix(numpy.zeros((5, 1)))
+ self.B[4, 0] = 1.0
+
+ # Coordinate transform fom absolute angles to relative angles.
+ # [output_position, output_velocity, spring_angle, spring_velocity, voltage]
+ abs_to_rel = numpy.matrix([[ 1.0, 0.0, 0.0, 0.0, 0.0],
+ [ 0.0, 1.0, 0.0, 0.0, 0.0],
+ [-1.0, 0.0, 1.0, 0.0, 0.0],
+ [ 0.0, -1.0, 0.0, 1.0, 0.0],
+ [ 0.0, 0.0, 0.0, 0.0, 1.0]])
+ # and back again.
+ rel_to_abs = numpy.matrix(numpy.linalg.inv(abs_to_rel))
+
+ # Now, get A and B in the relative coordinate system.
+ self.A_transformed_full = abs_to_rel * self.A * rel_to_abs
+ self.B_transformed_full = abs_to_rel * self.B
+
+ # Pull out the components of the dynamics which don't include the spring
+ # output positoin so we can do partial state feedback on what we care about.
+ self.A_transformed = self.A_transformed_full[1:5, 1:5]
+ self.B_transformed = self.B_transformed_full[1:5, 0]
+
+ glog.debug('A_transformed_full ' + str(self.A_transformed_full))
+ glog.debug('B_transformed_full ' + str(self.B_transformed_full))
+ glog.debug('A_transformed ' + str(self.A_transformed))
+ glog.debug('B_transformed ' + str(self.B_transformed))
+
+ # Now, let's design a controller in
+ # [output_velocity, spring_position, spring_velocity, delayed_voltage]
+ # space.
+
+ q_output_vel = 0.20
+ q_spring_pos = 0.05
+ q_spring_vel = 3.0
+ q_voltage = 100.0
+ self.Q_lqr = numpy.matrix(numpy.diag(
+ [1.0 / (q_output_vel ** 2.0),
+ 1.0 / (q_spring_pos ** 2.0),
+ 1.0 / (q_spring_vel ** 2.0),
+ 1.0 / (q_voltage ** 2.0)]))
+
+ self.R = numpy.matrix([[(1.0 / (12.0 ** 2.0))]])
+
+ self.K_transformed = controls.dlqr(self.A_transformed, self.B_transformed,
+ self.Q_lqr, self.R)
+
+ # Write the controller back out in the absolute coordinate system.
+ self.K = numpy.hstack((numpy.matrix([[0.0]]),
+ self.K_transformed)) * abs_to_rel
+
+ glog.debug('Poles are %s for %s',
+ repr(numpy.linalg.eig(
+ self.A_transformed -
+ self.B_transformed * self.K_transformed)[0]), self._name)
+ glog.debug('K is %s', repr(self.K_transformed))
+
+ # Design a kalman filter here as well.
+ q_pos = 0.05
+ q_vel = 2.65
+ q_volts = 0.005
+ self.Q = numpy.matrix(numpy.diag([(q_pos ** 2.0), (q_vel ** 2.0),
+ (q_pos ** 2.0), (q_vel ** 2.0),
+ (q_volts ** 2.0)]))
+
+ r_nm = 0.025
+ self.R = numpy.matrix(numpy.diag([(r_nm ** 2.0), (r_nm ** 2.0)]))
+
+ self.KalmanGain, self.Q_steady = controls.kalman(
+ A=self.A, B=self.B, C=self.C, Q=self.Q, R=self.R)
+
+ self.L = self.A * self.KalmanGain
+
+ # The box formed by U_min and U_max must encompass all possible values,
+ # or else Austin's code gets angry.
+ self.U_max = numpy.matrix([[12.0]])
+ self.U_min = numpy.matrix([[-12.0]])
+
+ self.InitializeState()
+
+
+class ScenarioPlotter(object):
+ def __init__(self):
+ # Various lists for graphing things.
+ self.t = []
+ self.x = []
+ self.v = []
+ self.goal_v = []
+ self.a = []
+ self.spring = []
+ self.x_hat = []
+ self.u = []
+
+ def run_test(self, intake, iterations=400, controller_intake=None,
+ observer_intake=None):
+ """Runs the intake plant with an initial condition and goal.
+
+ Test for whether the goal has been reached and whether the separation
+ goes outside of the initial and goal values by more than
+ max_separation_error.
+
+ Prints out something for a failure of either condition and returns
+ False if tests fail.
+ Args:
+ intake: intake object to use.
+ iterations: Number of timesteps to run the model for.
+ controller_intake: Intake object to get K from, or None if we should
+ use intake.
+ observer_intake: Intake object to use for the observer, or None if we
+ should use the actual state.
+ """
+
+ if controller_intake is None:
+ controller_intake = intake
+
+ vbat = 12.0
+
+ if self.t:
+ initial_t = self.t[-1] + intake.dt
+ else:
+ initial_t = 0
+
+ # Delay U by 1 cycle in our simulation to make it more realistic.
+ last_U = numpy.matrix([[0.0]])
+
+ for i in xrange(iterations):
+ X_hat = intake.X
+
+ if observer_intake is not None:
+ X_hat = observer_intake.X_hat
+ self.x_hat.append(observer_intake.X_hat[0, 0])
+
+ goal_angle = 3.0
+ goal_velocity = numpy.clip((goal_angle - X_hat[0, 0]) * 6.0, -10.0, 10.0)
+
+ self.goal_v.append(goal_velocity)
+
+ # Nominal: 1.8 N at 0.25 m -> 0.45 N m
+ # Nominal: 13 N at 0.25 m at 0.5 radians -> 3.25 N m -> 6 N m / radian
+
+ R = numpy.matrix([[0.0],
+ [goal_velocity],
+ [0.0],
+ [goal_velocity],
+ [goal_velocity / (intake.G * intake.Kv)]])
+ U = controller_intake.K * (R - X_hat) + R[4, 0]
+
+ U[0, 0] = numpy.clip(U[0, 0], -vbat, vbat)
+
+ self.x.append(intake.X[0, 0])
+ self.spring.append((intake.X[2, 0] - intake.X[0, 0]) * intake.Ks)
+
+ if self.v:
+ last_v = self.v[-1]
+ else:
+ last_v = 0
+
+ self.v.append(intake.X[1, 0])
+ self.a.append((self.v[-1] - last_v) / intake.dt)
+
+ if observer_intake is not None:
+ observer_intake.Y = intake.Y
+ observer_intake.CorrectObserver(U)
+
+ intake.Update(last_U + 0.0)
+
+ if observer_intake is not None:
+ observer_intake.PredictObserver(U)
+
+ self.t.append(initial_t + i * intake.dt)
+ self.u.append(U[0, 0])
+ last_U = U
+
+ def Plot(self):
+ pylab.subplot(3, 1, 1)
+ pylab.plot(self.t, self.x, label='x')
+ pylab.plot(self.t, self.x_hat, label='x_hat')
+ pylab.legend()
+
+ spring_ax1 = pylab.subplot(3, 1, 2)
+ spring_ax1.plot(self.t, self.u, 'k', label='u')
+ spring_ax2 = spring_ax1.twinx()
+ spring_ax2.plot(self.t, self.spring, label='spring_angle')
+ spring_ax1.legend(loc=2)
+ spring_ax2.legend()
+
+ accel_ax1 = pylab.subplot(3, 1, 3)
+ accel_ax1.plot(self.t, self.a, 'r', label='a')
+
+ accel_ax2 = accel_ax1.twinx()
+ accel_ax2.plot(self.t, self.v, label='v')
+ accel_ax2.plot(self.t, self.goal_v, label='goal_v')
+ accel_ax1.legend(loc=2)
+ accel_ax2.legend()
+
+ pylab.show()
+
+
+def main(argv):
+ scenario_plotter = ScenarioPlotter()
+
+ intake = Intake()
+ intake_controller = DelayedIntake()
+ observer_intake = DelayedIntake()
+
+ # Test moving the intake with constant separation.
+ scenario_plotter.run_test(intake, controller_intake=intake_controller,
+ observer_intake=observer_intake, iterations=200)
+
+ if FLAGS.plot:
+ scenario_plotter.Plot()
+
+ # Write the generated constants out to a file.
+ if len(argv) != 5:
+ glog.fatal('Expected .h file name and .cc file name for the intake and integral intake.')
+ else:
+ namespaces = ['y2018', 'control_loops', 'superstructure']
+ intake = Intake('Intake')
+ loop_writer = control_loop.ControlLoopWriter(
+ 'Intake', [intake], namespaces=namespaces)
+ loop_writer.Write(argv[1], argv[2])
+
+ integral_intake = IntegralIntake('IntegralIntake')
+ integral_loop_writer = control_loop.ControlLoopWriter(
+ 'IntegralIntake', [integral_intake], namespaces=namespaces)
+ integral_loop_writer.Write(argv[3], argv[4])
+
+
if __name__ == '__main__':
- main()
+ argv = FLAGS(sys.argv)
+ glog.init()
+ sys.exit(main(argv))
diff --git a/y2018/control_loops/python/intake_simple.py b/y2018/control_loops/python/intake_simple.py
new file mode 100644
index 0000000..9b6ffb1
--- /dev/null
+++ b/y2018/control_loops/python/intake_simple.py
@@ -0,0 +1,273 @@
+#!/usr/bin/python3
+
+# This code was used to select the gear ratio for the intake.
+# Run it from the command line and it displays the time required
+# to rotate the intake 180 degrees.
+#
+# Michael Schuh
+# January 20, 2018
+
+import math
+import numpy
+import scipy.integrate
+
+pi = math.pi
+pi2 = 2.0 * pi
+rad_to_deg = 180.0 / pi
+inches_to_meters = 0.0254
+lbs_to_kg = 1.0 / 2.2
+newton_to_lbf = 0.224809
+newton_meters_to_ft_lbs = 0.73756
+run_count = 0
+theta_travel = 0.0
+
+def to_deg(angle):
+ return angle * rad_to_deg
+
+def to_rad(angle):
+ return angle / rad_to_deg
+
+def to_rotations(angle):
+ return angle / pi2
+
+def time_derivative(x, t, voltage, c1, c2, c3):
+ global run_count
+ theta, omega = x
+ dxdt = [omega, -c1 * omega + c3 * math.sin(theta) + c2 * voltage]
+ run_count = run_count + 1
+
+ return dxdt
+
+def get_distal_angle(theta_proximal):
+ # For the proximal angle = -50 degrees, the distal angle is -180 degrees
+ # For the proximal angle = 10 degrees, the distal angle is -90 degrees
+ distal_angle = to_rad(-180.0 - (-50.0 - to_deg(theta_proximal)) * \
+ (180.0 - 90.0) / (50.0 + 10.0))
+ return distal_angle
+
+
+def get_180_degree_time(c1, c2, c3, voltage, gear_ratio, motor_free_speed):
+ global run_count
+ global theta_travel
+
+ if ( True ):
+ # Gravity is assisting the motion.
+ theta_start = 0.0
+ theta_target = pi
+ elif ( False ):
+ # Gravity is assisting the motion.
+ theta_start = 0.0
+ theta_target = -pi
+ elif ( False ):
+ # Gravity is slowing the motion.
+ theta_start = pi
+ theta_target = 0.0
+ elif ( False ):
+ # Gravity is slowing the motion.
+ theta_start = -pi
+ theta_target = 0.0
+ elif ( False ):
+ # This is for the proximal arm motion.
+ theta_start = to_rad(-50.0)
+ theta_target = to_rad(10.0)
+
+ theta_half = 0.5 * (theta_start + theta_target)
+ if theta_start > theta_target:
+ voltage = -voltage
+ theta = theta_start
+ theta_travel = theta_start - theta_target
+ if run_count == 0:
+ print("# Theta Start = %.2f radians End = %.2f Theta travel %.2f "
+ "Theta half = %.2f Voltage = %.2f" % (
+ theta_start, theta_target, theta_travel, theta_half, voltage))
+ print("# Theta Start = %.2f degrees End = %.2f Theta travel %.2f "
+ "Theta half = %.2f Voltage = %.2f" % (
+ to_deg(theta_start), to_deg(theta_target), to_deg(theta_travel),
+ to_deg(theta_half), voltage))
+ omega = 0.0
+ time = 0.0
+ delta_time = 0.01 # time step in seconds
+ for step in range(1, 5000):
+ t = numpy.array([time, time + delta_time])
+ time = time + delta_time
+ x = [theta, omega]
+ angular_acceleration = -c1 * omega + c2 * voltage
+ x_n_plus_1 = scipy.integrate.odeint(time_derivative, x, t,
+ args=(voltage, c1, c2, c3))
+ theta, omega = x_n_plus_1[1]
+
+ if ( False ):
+ print("%4d %8.4f %8.2f %8.4f %8.4f %8.3f "
+ "%8.3f %8.3f %8.3f" % (
+ step, time, theta, omega, angular_acceleration,
+ to_rotations(theta), to_rotations(omega),
+ omega * gear_ratio * 60.0 / pi2,
+ omega * gear_ratio / motor_free_speed))
+ if theta_start < theta_target:
+ # Angle is increasing through the motion.
+ if theta > theta_half:
+ break
+ else:
+ # Angle is decreasing through the motion.
+ if (theta < theta_half):
+ break
+
+ return 2.0 * time
+
+def main():
+ # m/sec^2 Gravity Constant
+ gravity = 9.8
+ # m/sec^2 Gravity Constant - Use 0.0 for the intake. It is horizontal.
+ gravity = 0.0
+ # Volts
+ voltage_nominal = 12
+
+ # Vex 775 Pro motor specs from http://banebots.com/p/M2-RS550-120
+ motor_name = "Vex 775 Pro motor specs from http://banebots.com/p/M2-RS550-120"
+ current_stall = 134 # amps stall current
+ current_no_load = 0.7 # amps no load current
+ torque_stall = 710/1000.0 # N-m Stall Torque
+ speed_no_load_rpm = 18730 # RPM no load speed
+
+ if ( True ):
+ # Bag motor from https://www.vexrobotics.com/217-3351.html
+ motor_name = "Bag motor from https://www.vexrobotics.com/217-3351.html"
+ current_stall = 53.0 # amps stall current
+ current_no_load = 1.8 # amps no load current
+ torque_stall = 0.4 # N-m Stall Torque
+ speed_no_load_rpm = 13180.0 # RPM no load speed
+
+ if ( False ):
+ # Mini CIM motor from https://www.vexrobotics.com/217-3371.html
+ motor_name = "Mini CIM motor from https://www.vexrobotics.com/217-3371.html"
+ current_stall = 89.0 # amps stall current
+ current_no_load = 3.0 # amps no load current
+ torque_stall = 1.4 # N-m Stall Torque
+ speed_no_load_rpm = 5840.0 # RPM no load speed
+
+ # How many motors are we using?
+ num_motors = 1
+
+ # Motor values
+ print("# Motor: %s" % (motor_name))
+ print("# Number of motors: %d" % (num_motors))
+ print("# Stall torque: %.1f n-m" % (torque_stall))
+ print("# Stall current: %.1f amps" % (current_stall))
+ print("# No load current: %.1f amps" % (current_no_load))
+ print("# No load speed: %.0f rpm" % (speed_no_load_rpm))
+
+ # Constants from motor values
+ resistance_motor = voltage_nominal / current_stall
+ speed_no_load_rps = speed_no_load_rpm / 60.0 # Revolutions per second no load speed
+ speed_no_load = speed_no_load_rps * 2.0 * pi
+ Kt = num_motors * torque_stall / current_stall # N-m/A torque constant
+ Kv_rpm = speed_no_load_rpm / (voltage_nominal -
+ resistance_motor * current_no_load) # rpm/V
+ Kv = Kv_rpm * 2.0 * pi / 60.0 # rpm/V
+
+ # Robot Geometry and physics
+ # m Length of arm connected to the robot base
+ length_proximal_arm = inches_to_meters * 47.34
+ # m Length of arm that holds the cube
+ length_distal_arm = inches_to_meters * 44.0
+ # m Length of intake arm from the pivot point to where the big roller contacts a cube.
+ length_intake_arm = inches_to_meters * 9.0
+ mass_cube = 6.0 * lbs_to_kg # Weight of the cube in Kgrams
+ mass_proximal_arm = 5.5 * lbs_to_kg # Weight of proximal arm
+ mass_distal_arm = 3.5 * lbs_to_kg # Weight of distal arm
+ mass_distal = mass_cube + mass_distal_arm
+ mass_proximal = mass_proximal_arm + mass_distal
+ # m Length from arm pivot point to arm CG
+ radius_to_proximal_arm_cg = 22.0 * inches_to_meters
+ # m Length from arm pivot point to arm CG
+ radius_to_distal_arm_cg = 10.0 * inches_to_meters
+
+ radius_to_distal_cg = (length_distal_arm * mass_cube +
+ radius_to_distal_arm_cg * mass_distal_arm) / \
+ mass_distal
+ radius_to_proximal_cg = (length_proximal_arm * mass_distal +
+ radius_to_proximal_arm_cg * mass_proximal_arm) / \
+ mass_proximal
+ J_cube = length_distal_arm * length_distal_arm*mass_cube
+ # Kg m^2 Moment of inertia of the proximal arm
+ J_proximal_arm = radius_to_proximal_arm_cg * radius_to_proximal_arm_cg * \
+ mass_distal_arm
+ # Kg m^2 Moment of inertia distal arm and cube at end of proximal arm.
+ J_distal_arm_and_cube_at_end_of_proximal_arm = length_proximal_arm * \
+ length_proximal_arm * mass_distal
+ # Kg m^2 Moment of inertia of the distal arm
+ J_distal_arm = radius_to_distal_arm_cg * radius_to_distal_arm_cg * mass_distal_arm
+ # Moment of inertia of the arm with the cube on the end
+ J = J_distal_arm_and_cube_at_end_of_proximal_arm + J_proximal_arm
+ # Intake claw
+ J_intake = 0.295 # Kg m^2 Moment of inertia of intake
+ J = J_intake
+
+ gear_ratio = 140.0 # Guess at the gear ratio
+ gear_ratio = 100.0 # Guess at the gear ratio
+ gear_ratio = 90.0 # Guess at the gear ratio
+
+ error_margine = 1.0
+ voltage = 10.0 # voltage for the motor. Assuming a loaded robot so not using 12 V.
+ # It might make sense to use a lower motor frees peed when the voltage is not a full 12 Volts.
+ # motor_free_speed = Kv * voltage
+ motor_free_speed = speed_no_load
+
+ print("# Kt = %f N-m/A\n# Kv_rpm = %f rpm/V\n# Kv = %f radians/V" % (Kt, Kv_rpm, Kv))
+ print("# %.2f Ohms Resistance of the motor " % (resistance_motor))
+ print("# %.2f kg Cube weight" % (mass_cube))
+ print("# %.2f kg Proximal Arm mass" % (mass_proximal_arm))
+ print("# %.2f kg Distal Arm mass" % (mass_distal_arm))
+ print("# %.2f kg Distal Arm and Cube weight" % (mass_distal))
+ print("# %.2f m Length from distal arm pivot point to arm CG" % (
+ radius_to_distal_arm_cg))
+ print("# %.2f m Length from distal arm pivot point to arm and cube cg" % (
+ radius_to_distal_cg))
+ print("# %.2f kg-m^2 Moment of inertia of the cube about the arm pivot point" % (J_cube))
+ print("# %.2f m Length from proximal arm pivot point to arm CG" % (radius_to_proximal_arm_cg))
+ print("# %.2f m Length from proximal arm pivot point to arm and cube cg" % (
+ radius_to_proximal_cg))
+ print("# %.2f m Proximal arm length" % (length_proximal_arm))
+ print("# %.2f m Distal arm length" % (length_distal_arm))
+
+ print("# %.2f kg-m^2 Moment of inertia of the intake about the intake pivot point" % (
+ J_intake))
+ print("# %.2f kg-m^2 Moment of inertia of the distal arm about the arm pivot point" % (
+ J_distal_arm))
+ print("# %.2f kg-m^2 Moment of inertia of the proximal arm about the arm pivot point" % (
+ J_proximal_arm))
+ print("# %.2f kg-m^2 Moment of inertia of the distal arm and cube mass about "
+ "the proximal arm pivot point" % (
+ J_distal_arm_and_cube_at_end_of_proximal_arm))
+ print("# %.2f kg-m^2 Moment of inertia of the intake the intake pivot point "
+ "(J value used in simulation)" % (J))
+ print("# %d Number of motors" % (num_motors))
+
+ print("# %.2f V Motor voltage" % (voltage))
+ for gear_ratio in range(60, 241, 10):
+ c1 = Kt * gear_ratio * gear_ratio / (Kv * resistance_motor * J)
+ c2 = gear_ratio * Kt / (J * resistance_motor)
+ c3 = radius_to_proximal_cg * mass_proximal * gravity / J
+
+ if ( False ):
+ print("# %.8f 1/sec C1 constant" % (c1))
+ print("# %.2f 1/sec C2 constant" % (c2))
+ print("# %.2f 1/(V sec^2) C3 constant" % (c3))
+ print("# %.2f RPM Free speed at motor voltage" % (voltage * Kv_rpm))
+
+ torque_90_degrees = radius_to_distal_cg * mass_distal * gravity
+ voltage_90_degrees = resistance_motor * torque_90_degrees / (gear_ratio * Kt)
+ torque_peak = gear_ratio * num_motors * torque_stall
+ torque_peak_ft_lbs = torque_peak * newton_meters_to_ft_lbs
+ normal_force = torque_peak / length_intake_arm
+ normal_force_lbf = newton_to_lbf * normal_force
+ time_required = get_180_degree_time(c1, c2, c3, voltage,
+ gear_ratio, motor_free_speed)
+ print("Time for %.1f degrees for gear ratio %3.0f is %.2f seconds. "
+ "Peak (stall) torque %3.0f nm %3.0f ft-lb Normal force at intake "
+ "end %3.0f N %2.0f lbf" % \
+ (to_deg(theta_travel), gear_ratio, time_required,
+ torque_peak, torque_peak_ft_lbs, normal_force, normal_force_lbf))
+
+if __name__ == '__main__':
+ main()