Speed bump design

Speed Bump

Role

This module plans the velocity of the related part of the path in case there is speed bump regulatory element referring to it.

Activation Timing

The manager launch speed bump scene module when there is speed bump regulatory element referring to the reference path.

Module Parameters

Parameter	Type	Description
slow_start_margin	double	[m] margin for ego vehicle to slow down before speed_bump
slow_end_margin	double	[m] margin for ego vehicle to accelerate after speed_bump
print_debug_info	bool	whether debug info will be printed or not

Speed Calculation

• limits for speed bump height and slow down speed to create a linear equation

Parameter	Type	Description
min_height	double	[m] minimum height assumption of the speed bump
max_height	double	[m] maximum height assumption of the speed bump
min_speed	double	[m/s] minimum speed assumption of slow down speed
max_speed	double	[m/s] maximum speed assumption of slow down speed

Inner-workings / Algorithms

• Get speed bump regulatory element on the path from lanelet2 map
• Calculate slow_down_speed wrt to speed_bump_height specified in regulatory element or read slow_down_speed tag from speed bump annotation if available

Note: If in speed bump annotation slow_down_speed tag is used then calculating the speed wrt the speed bump height will be ignored. In such case, specified slow_down_speed value in [kph] is being used.

• Get the intersection points between path and speed bump polygon
• Calculate slow_start_point & slow_end_point wrt the intersection points and insert them to path
• If slow_start_point or slow_end_point can not be inserted with given/calculated offset values check if any path point can be virtually assigned as slow_start_point or slow_end_point

• Assign slow_down_speed to the path points between slow_start_point or slow_end_point

Future Work

• In an article here, a bump modeling method is proposed. Simply it is based on fitting the bump in a circle and a radius calculation is done with it. Although the velocity calculation is based on just the height of the bump in the recent implementation, applying this method is intended in the future which will yield more realistic results.