motion

hw3.py

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+
+# --------------
+# USER INSTRUCTIONS
+#
+# Write a function in the class robot called move()
+#
+# that takes self and a motion vector (this
+# motion vector contains a steering* angle and a
+# distance) as input and returns an instance of the class
+# robot with the appropriate x, y, and orientation
+# for the given motion.
+#
+# *steering is defined in the video
+# which accompanies this problem.
+#
+# For now, please do NOT add noise to your move function.
+#
+# Please do not modify anything except where indicated
+# below.
+#
+# There are test cases which you are free to use at the
+# bottom. If you uncomment them for testing, make sure you
+# re-comment them before you submit.
+
+from math import *
+import random
+# --------
+# 
+# the "world" has 4 landmarks.
+# the robot's initial coordinates are somewhere in the square
+# represented by the landmarks.
+#
+# NOTE: Landmark coordinates are given in (y, x) form and NOT
+# in the traditional (x, y) format!
+
+landmarks  = [[0.0, 100.0], [0.0, 0.0], [100.0, 0.0], [100.0, 100.0]] # position of 4 landmarks
+world_size = 100.0 # world is NOT cyclic. Robot is allowed to travel "out of bounds"
+max_steering_angle = pi/4 # You don't need to use this value, but it is good to keep in mind the limitations of a real car.
+
+# ------------------------------------------------
+# 
+# this is the robot class
+#
+
+class robot:
+
+    # --------
+
+    # init: 
+    # creates robot and initializes location/orientation 
+    #
+
+    def __init__(self, length = 10.0):
+        self.x = random.random() * world_size # initial x position
+        self.y = random.random() * world_size # initial y position
+        self.orientation = random.random() * 2.0 * pi # initial orientation
+        self.length = length # length of robot
+        self.bearing_noise  = 0.0 # initialize bearing noise to zero
+        self.steering_noise = 0.0 # initialize steering noise to zero
+        self.distance_noise = 0.0 # initialize distance noise to zero
+
+    def __repr__(self):
+        return '[x=%.6s y=%.6s orient=%.6s]' % (str(self.x), str(self.y), str(self.orientation))
+    # --------
+    # set: 
+    # sets a robot coordinate
+    #
+
+    def set(self, new_x, new_y, new_orientation):
+
+        if new_orientation < 0 or new_orientation >= 2 * pi:
+            raise ValueError, 'Orientation must be in [0..2pi]'
+        self.x = float(new_x)
+        self.y = float(new_y)
+        self.orientation = float(new_orientation)
+
+
+    # --------
+    # set_noise: 
+    # sets the noise parameters
+    #
+
+    def set_noise(self, new_b_noise, new_s_noise, new_d_noise):
+        # makes it possible to change the noise parameters
+        # this is often useful in particle filters
+        self.bearing_noise  = float(new_b_noise)
+        self.steering_noise = float(new_s_noise)
+        self.distance_noise = float(new_d_noise)
+
+    ############# ONLY ADD/MODIFY CODE BELOW HERE ###################
+
+    # --------
+    # move:
+    #   move along a section of a circular path according to motion
+    #
+
+    def move(self, motion): # Do not change the name of this function
+
+        # ADD CODE HERE
+        steer = motion[0]
+        distance = motion[1]
+        theta = self.orientation
+        beta = distance / self.length * tan(steer)
+        if abs(beta) >= 0.0001:
+           radius =  distance / beta
+           Cx = self.x - radius * sin(theta)
+           Cy = self.y + radius * cos(theta)
+           x_prime = Cx + radius * sin(beta+theta)
+           y_prime = Cy - radius * cos(beta+theta)
+           theta_prime = (theta + beta) % (2 * pi)
+           self.set(x_prime, y_prime, theta_prime)
+        else:
+           x_prime = self.x + distance * cos(theta)
+           y_prime = self.y + distance * sin(theta)
+           theta_prime = (theta + beta) % (2 * pi)
+           self.set(x_prime, y_prime, theta_prime)
+
+        result = self
+        return result # make sure your move function returns an instance
+                      # of the robot class with the correct coordinates.
+
+    ############## ONLY ADD/MODIFY CODE ABOVE HERE ####################
+
+
+## IMPORTANT: You may uncomment the test cases below to test your code.
+## But when you submit this code, your test cases MUST be commented
+## out. Our testing program provides its own code for testing your
+## move function with randomized motion data.
+
+## --------
+## TEST CASE:
+## 
+## 1) The following code should print:
+##       Robot:     [x=0.0 y=0.0 orient=0.0]
+##       Robot:     [x=10.0 y=0.0 orient=0.0]
+##       Robot:     [x=19.861 y=1.4333 orient=0.2886]
+##       Robot:     [x=39.034 y=7.1270 orient=0.2886]
+##
+##
+length = 20.
+bearing_noise  = 0.0
+steering_noise = 0.0
+distance_noise = 0.0
+
+myrobot = robot(length)
+myrobot.set(0.0, 0.0, 0.0)
+myrobot.set_noise(bearing_noise, steering_noise, distance_noise)
+
+motions = [[0.0, 10.0], [pi / 6.0, 10], [0.0, 20.0]]
+
+T = len(motions)
+
+print 'Robot:    ', myrobot
+for t in range(T):
+    myrobot = myrobot.move(motions[t])
+    print 'Robot:    ', myrobot
+
+
+
+## IMPORTANT: You may uncomment the test cases below to test your code.
+## But when you submit this code, your test cases MUST be commented
+## out. Our testing program provides its own code for testing your
+## move function with randomized motion data.
+
+
+## 2) The following code should print:
+##      Robot:     [x=0.0 y=0.0 orient=0.0]
+##      Robot:     [x=9.9828 y=0.5063 orient=0.1013]
+##      Robot:     [x=19.863 y=2.0201 orient=0.2027]
+##      Robot:     [x=29.539 y=4.5259 orient=0.3040]
+##      Robot:     [x=38.913 y=7.9979 orient=0.4054]
+##      Robot:     [x=47.887 y=12.400 orient=0.5067]
+##      Robot:     [x=56.369 y=17.688 orient=0.6081]
+##      Robot:     [x=64.273 y=23.807 orient=0.7094]
+##      Robot:     [x=71.517 y=30.695 orient=0.8108]
+##      Robot:     [x=78.027 y=38.280 orient=0.9121]
+##      Robot:     [x=83.736 y=46.485 orient=1.0135]
+##
+##
+length = 20.
+bearing_noise  = 0.0
+steering_noise = 0.0
+distance_noise = 0.0
+
+myrobot = robot(length)
+myrobot.set(0.0, 0.0, 0.0)
+myrobot.set_noise(bearing_noise, steering_noise, distance_noise)
+
+motions = [[0.2, 10.] for row in range(10)]
+
+T = len(motions)
+
+print 'Robot:    ', myrobot
+for t in range(T):
+    myrobot = myrobot.move(motions[t])
+    print 'Robot:    ', myrobot
+
+## IMPORTANT: You may uncomment the test cases below to test your code.
+## But when you submit this code, your test cases MUST be commented
+## out. Our testing program provides its own code for testing your
+## move function with randomized motion data.
+
+
+