Kalman-and-Bayesian-Filters.../code/DogSimulation.py

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# -*- coding: utf-8 -*-
"""
Created on Sun May 11 13:21:39 2014
@author: rlabbe
"""
from __future__ import print_function, division
from numpy.random import randn
import math
class DogSimulation(object):
def __init__(self, x0=0, velocity=1,
measurement_variance=0.0, process_variance=0.0):
""" x0 - initial position
velocity - (+=right, -=left)
measurement_variance - variance in measurement m^2
process_variance - variance in process (m/s)^2
"""
self.x = x0
self.velocity = velocity
self.measurement_noise = math.sqrt(measurement_variance)
self.process_noise = math.sqrt(process_variance)
def move(self, dt=1.0):
'''Compute new position of the dog assuming `dt` seconds have
passed since the last update.'''
# compute new position based on velocity. Add in some
# process noise
velocity = self.velocity + randn() * self.process_noise
self.x += velocity * dt
def sense_position(self):
# simulate measuring the position with noise
measurement = self.x + randn() * self.measurement_noise
return measurement
def move_and_sense(self, dt=1.0):
self.move(dt)
return self.sense_position()