niryo_libraries.angles

package documentation

Undocumented

From __init__.py:

Function normalize_angle Normalizes the angle to be -pi to +pi It takes and returns radians.
Function normalize_angle_positive Normalizes the angle to be 0 to 2*pi It takes and returns radians.
Function shortest_angular_distance Given 2 angles, this returns the shortest angular difference. The inputs and ouputs are of course radians.
Function shortest_angular_distance_with_large_limits Returns the delta from from_angle to to_angle, making sure it does not violate limits specified by left_limit and right_limit. This function is similar to shortest_angular_distance_with_limits(), with the main difference that it accepts limits outside the ...
Function shortest_angular_distance_with_limits Returns the delta from "from_angle" to "to_angle" making sure it does not violate limits specified by left_limit and right_limit. The valid interval of angular positions is [left_limit,right_limit]. E.
Function two_pi_complement returns the angle in [-2*pi, 2*pi] going the other way along the unit circle. param angle The angle to which you want to turn in the range [-2*pi, 2*pi]
Function _find_min_max_delta This function is only intended for internal use and not intended for external use. If you do use it, read the documentation very carefully.
def normalize_angle_positive(angle):

Normalizes the angle to be 0 to 2*pi It takes and returns radians.

def normalize_angle(angle):

Normalizes the angle to be -pi to +pi It takes and returns radians.

def shortest_angular_distance(from_angle, to_angle):

Given 2 angles, this returns the shortest angular difference. The inputs and ouputs are of course radians.

The result would always be -pi <= result <= pi. Adding the result to "from" will always get you an equivelent angle to "to".

def two_pi_complement(angle):

returns the angle in [-2*pi, 2*pi] going the other way along the unit circle. param angle The angle to which you want to turn in the range [-2*pi, 2*pi]

E.g. two_pi_complement(-pi/4) returns 7_pi/4
two_pi_complement(pi/4) returns -7*pi/4
def _find_min_max_delta(from_angle, left_limit, right_limit):

This function is only intended for internal use and not intended for external use. If you do use it, read the documentation very carefully.

Returns the min and max amount (in radians) that can be moved from "from" angle to "left_limit" and "right_limit".

param from - "from" angle - must lie in [-pi, pi) param left_limit - left limit of valid interval for angular position

  • must lie in [-pi, pi], left and right limits are specified on the unit circle w.r.t to a reference pointing inwards
param right_limit - right limit of valid interval for angular position
  • must lie in [-pi, pi], left and right limits are specified on the unit circle w.r.t to a reference pointing inwards
eturn (valid, min, max) - angle in radians that can be moved from "from" position before hitting the joint stop
valid is False if "from" angle does not lie in the interval [left_limit,right_limit]
def shortest_angular_distance_with_limits(from_angle, to_angle, left_limit, right_limit):

Returns the delta from "from_angle" to "to_angle" making sure it does not violate limits specified by left_limit and right_limit. The valid interval of angular positions is [left_limit,right_limit]. E.g., [-0.25,0.25] is a 0.5 radians wide interval that contains 0. But [0.25,-0.25] is a 2*pi-0.5 wide interval that contains pi (but not 0). The value of shortest_angle is the angular difference between "from" and "to" that lies within the defined valid interval.

E.g. shortest_angular_distance_with_limits(-0.5,0.5,0.25,-0.25) returns 2*pi-1.0
shortest_angular_distance_with_limits(-0.5,0.5,-0.25,0.25) returns None since -0.5 and 0.5 do not lie in the interval [-0.25,0.25]
param left_limit - left limit of valid interval for angular position
  • must lie in [-pi, pi], left and right limits are specified on the unit circle w.r.t to a reference pointing inwards
param right_limit - right limit of valid interval for angular position
  • must lie in [-pi, pi], left and right limits are specified on the unit circle w.r.t to a reference pointing inwards

eturns valid_flag, shortest_angle

def shortest_angular_distance_with_large_limits(from_angle, to_angle, left_limit, right_limit):

Returns the delta from from_angle to to_angle, making sure it does not violate limits specified by left_limit and right_limit. This function is similar to shortest_angular_distance_with_limits(), with the main difference that it accepts limits outside the [-M_PI, M_PI] range. Even if this is quite uncommon, one could indeed consider revolute joints with large rotation limits, e.g., in the range [-2*M_PI, 2*M_PI].

In this case, a strict requirement is to have left_limit smaller than right_limit. Note also that from_angle must lie inside the valid range, while to_angle does not need to. In fact, this function will evaluate the shortest (valid) angle shortest_angle so that from_angle+shortest_angle equals to_angle up to an integer multiple of 2*M_PI. As an example, a call to shortest_angular_distance_with_large_limits(0, 10.5*M_PI, -2*M_PI, 2*M_PI) will return true, with shortest_angle=0.5*M_PI. This is because from_angle and from_angle+shortest_angle are both inside the limits, and fmod(to_angle+shortest_angle, 2*M_PI) equals fmod(to_angle, 2*M_PI). On the other hand, shortest_angular_distance_with_large_limits(10.5*M_PI, 0, -2*M_PI, 2*M_PI) will return false, since from_angle is not in the valid range. Finally, note that the call shortest_angular_distance_with_large_limits(0, 10.5*M_PI, -2*M_PI, 0.1*M_PI) will also return true. However, shortest_angle in this case will be -1.5*M_PI.

eturn valid_flag, shortest_angle - valid_flag will be true if left_limit < right_limit and if "from_angle" and "from_angle+shortest_angle" positions are within the valid interval, false otherwise. param left_limit - left limit of valid interval, must be smaller than right_limit. param right_limit - right limit of valid interval, must be greater than left_limit.