Homework 1 - Lidar Functions

[cmurray3]

Your assignment is to write 3 Python functions that will use Lidar data in the format sensor_msgs/LaserScan.

1. Get the distance at a particular angle.
2. Get the distances over a range of angles.
   • For this, your function should return a list of distances.
3. Get size of gap/opening x meters ahead.
   • The idea is to use this function to determine if the space in front of your robot is "open".

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Assumptions

• All angles in radians
• All distances in meters

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Some sample code

import math
TWO_PI = math.pi*2
PI     = math.pi

# Limit the input angle to be no more than 360-degrees (2pi radians):
inputAngleRad = inputAngleRad % TWO_PI

def degrees2radians(deg):
    # Convert a given number of degrees to radians
    return deg * (TWO_PI/360)

[cmurray3]

Some code from today's class:

def getIndex(angle_desired, incr, min_angle, max_angle, is_cw):

    returns the index for a given angle

def f(angle_desired, ranges, incr, min_angle, max_angle, is_cw):
    '''
    This function returns the distance (in meters) at an angle of `angle_desired`.

    INPUTS:
        - angle_desired.  
        - ranges.  List of distances.  See LaserScan.ranges for example
    OUTPUT:
    '''

    myIndex = getIndex(angle_desired, incr, min_angle, max_angle, is_cw)

    return ranges[myIndex]

def g(angle_start, angle_end, ranges, incr, min_angle, max_angle, is_cw):
    myStartIndex = getIndex(angle_start, incr, min_angle, max_angle, is_cw)
    myEndIndex   = getIndex(angle_end,   incr, min_angle, max_angle, is_cw)

    return ranges[myStartIndex : myEndIndex + 1]

[cmurray3]

Use this link to submit your assignment: https://classroom.github.com/a/QKnftk6K