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Vehicle dimensions#

Autoware describes the size of the vehicle with the parameters in vehicle_info.param.yaml. Each vehicle description package has this file, for example autoware_sample_vehicle_description. The autoware_vehicle_info_utils package reads the parameters and calculates the values that depend on them.

The current format supports only the Ackermann model. It is the model that planning and control use. It does not have to be the exact physical model of the vehicle.

The base_link frame is on the ground below the center of the rear axle. The x axis points forward, the y axis points to the left, and the z axis points up. Roll, pitch, and yaw are the rotations around x, y, and z.Top view+x+yyawbase_link (the +z axis points out of the page)Side view+x+zpitchrollyawbase_link (the +y axis points into the page)
The axes of the base_link frame.

The base_link frame is used very frequently throughout the Autoware stack. It is the projection of the rear-axle center onto the ground surface.

  • The Localization component outputs the map to base_link transformation.
  • The Planning component plans the poses for where the base_link frame should be in the future.
  • The Control component tries to fit base_link to incoming poses.

Vehicle dimensions#

A top view of the vehicle with its dimensions: front_overhang, wheel_base, and rear_overhang add up to vehicle_length. left_overhang, wheel_tread, and right_overhang add up to vehicle_width, measured to the tips of the side mirrors. The front wheels show a positive steering angle, which turns the vehicle to the left.+30°+xbase_linkrear_overhangwheel_basefront_overhangvehicle_lengthleft_overhangwheel_treadright_overhangvehicle_widthLeft sideRight side
The dimensions of the vehicle in the top view. The front wheels show a positive steering angle.

All lengths are in meters.

wheel_base#

The distance between the front and rear axles.

wheel_tread#

The distance between the centers of the left and right wheels.

Overhangs#

Overhangs are part of the minimum safety box calculation.

When measuring overhangs, side mirrors, protruding sensors and wheels should be taken into consideration.

left_overhang#

The distance between the axis centers of the left wheels and the left-most point of the vehicle.

right_overhang#

The distance between the axis centers of the right wheels and the right-most point of the vehicle.

front_overhang#

The distance between the front axle and the foremost point of the vehicle.

rear_overhang#

The distance between the rear axle and the rear-most point of the vehicle.

vehicle_height#

The height of the vehicle from the ground.

max_steer_angle#

The maximum steering angle of the tires, in radians.

vehicle_length#

Total length of the vehicle. Calculated by front_overhang + wheel_base + rear_overhang

vehicle_width#

Total width of the vehicle. Calculated by left_overhang + wheel_tread + right_overhang

Wheel parameters#

wheel_width is the width of the tire in the front view. wheel_radius is the distance from the center of the wheel to the edge of the tire in the side view.Front viewwheel_widthSide viewwheel_radius
The width and the radius of a wheel.

wheel_width#

The lateral width of a wheel tire, primarily used for dead reckoning.

wheel_radius#

The radius of the wheel, primarily used for dead reckoning.

Footprint#

The footprint polygon that Autoware makes from the vehicle dimensions has six points in clockwise order: front left, front right, center right, rear right, rear left, and center left. Its origin is base_link, with x forward and y to the left.+x+ybase_link1234561: front left2: front right3: center right4: rear right5: rear left6: center left
The footprint polygon that Autoware makes from the vehicle dimensions.

The footprint is the minimum collision area of the vehicle. It is not a parameter. The createFootprint() function of autoware_vehicle_info_utils makes it from the dimensions above. The points are in clockwise order, with the origin on base_link. The center points are at half of wheel_base. A planning or control module can add a lateral or longitudinal margin to the footprint.

The AD API reports the dimensions and a footprint polygon of the vehicle through /api/vehicle/dimensions.

Wheel orientations#

If the vehicle is going forward, a positive wheel angle will result in the vehicle turning left.

Autoware assumes the rear wheels don't turn on z axis.