in webserver_pkg/webserver_pkg/vehicle_control.py [0:0]
def get_rescaled_manual_speed(categorized_throttle, max_speed_pct):
"""Return the non linearly rescaled speed value based on the max_speed_pct.
Args:
categorized_throttle (float): Float value ranging from -1.0 to 1.0.
max_speed_pct (float): Float value ranging from 0.0 to 1.0 taken as input
from maximum speed input.
Returns:
float: Categorized value of the input speed.
"""
"""
Example return values:
categorized_throttle: -0.3 max_speed_pct: 0.1 mapped_speed: -0.1383742911153119
categorized_throttle: -0.5 max_speed_pct: 0.1 mapped_speed: -0.224952741020794
categorized_throttle: -0.8 max_speed_pct: 0.1 mapped_speed: -0.3463137996219282
categorized_throttle: -0.3 max_speed_pct: 0.5 mapped_speed: -0.208
categorized_throttle: -0.5 max_speed_pct: 0.5 mapped_speed: -0.33333333333333337
categorized_throttle: -0.8 max_speed_pct: 0.5 mapped_speed: -0.5013333333333334
categorized_throttle: -0.3 max_speed_pct: 1.0 mapped_speed: -0.552
categorized_throttle: -0.5 max_speed_pct: 1.0 mapped_speed: -0.8
categorized_throttle: -0.8 max_speed_pct: 1.0 mapped_speed: -0.992
categorized_throttle: 0.3 max_speed_pct: 0.1 mapped_speed: 0.1383742911153119
categorized_throttle: 0.5 max_speed_pct: 0.1 mapped_speed: 0.224952741020794
categorized_throttle: 0.8 max_speed_pct: 0.1 mapped_speed: 0.3463137996219282
categorized_throttle: 0.3 max_speed_pct: 0.5 mapped_speed: 0.208
categorized_throttle: 0.5 max_speed_pct: 0.5 mapped_speed: 0.33333333333333337
categorized_throttle: 0.8 max_speed_pct: 0.5 mapped_speed: 0.5013333333333334
categorized_throttle: 0.3 max_speed_pct: 1.0 mapped_speed: 0.552
categorized_throttle: 0.5 max_speed_pct: 1.0 mapped_speed: 0.8
categorized_throttle: 0.8 max_speed_pct: 1.0 mapped_speed: 0.992
"""
# return 0.0 if categorized_throttle or maximum speed pct is 0.0
if categorized_throttle == 0.0 or max_speed_pct == 0.0:
return 0.0
# get the parameter value to calculate the coefficients a, b in the equation y=ax^2+bx
# The lower the update_speed_scale_value parameter, higher the impact on the
# final mapped_speed.
# Hence the update_speed_scale_value parameter is inversely associated with max_speed_pct
# and bounded by MANUAL_SPEED_SCALE_BOUNDS.
# Ex: max_speed_pct = 0.5; update_speed_scale_value = 3
# max_speed_pct = 1.0; update_speed_scale_value = 1
# Lower the update_speed_scale_value: categorized_throttle value gets mapped to
# higher possible values.
# Example: update_speed_scale_value = 1.0;
# categorized_throttle = 0.8 ==> mapped_speed = 0.992
# Higher the update_speed_scale_value: categorized_throttle value gets mapped to
# lower possible values.
# Example: update_speed_scale_value = 3.0;
# categorized_throttle = 0.8 ==> mapped_speed = 0.501
inverse_max_speed_pct = (1 - max_speed_pct)
update_speed_scale_value = \
constants.MANUAL_SPEED_SCALE_BOUNDS[0] + \
inverse_max_speed_pct * \
(constants.MANUAL_SPEED_SCALE_BOUNDS[1] - constants.MANUAL_SPEED_SCALE_BOUNDS[0])
speed_mapping_coefficients = dict()
# recreate the mapping coefficeints for the non-linear equation ax^2 + bx based on
# the update_speed_scale_value.
# These coefficents map the [update_speed_scale_value, update_speed_scale_value/2]
# values to DEFAULT_SPEED_SCALE values [1.0, 0.8].
speed_mapping_coefficients["a"] = \
(1.0 / update_speed_scale_value**2) * \
(2.0 * constants.DEFAULT_SPEED_SCALES[0] - 4.0 * constants.DEFAULT_SPEED_SCALES[1])
speed_mapping_coefficients["b"] = \
(1.0 / update_speed_scale_value) * \
(4.0 * constants.DEFAULT_SPEED_SCALES[1] - constants.DEFAULT_SPEED_SCALES[0])
return math.copysign(1.0, categorized_throttle) * \
(speed_mapping_coefficients["a"] * abs(categorized_throttle)**2 +
speed_mapping_coefficients["b"] * abs(categorized_throttle))