Stanley Steering

Stanley Steering#

Stanley is a pure path following method designed to track a reference by computing an orientation and cross-track errors [1]

Tip

Although Stanley is a pure path following method, it can be used in KOMPASS in the Controller component in combination with the Drive Manager Component to provide following + emergency stop.

Supported Motion Models#

  • ACKERMANN

  • DIFFERENTIAL_DRIVE

  • OMNI

Note

Stanley is designed for ACKERMANN models, however, it is adjusted for all models in Kompass by adapting a rotate-then-move strategy for non ACKERMANN robot.

Supported Sensory Inputs#

Does not require sensory input for obstacles

Parameters and Default Values#

Name

Type

Default

Description

heading_gain

float

0.7

Heading gain in the control law. Must be between 0.0 and 1e2.

cross_track_min_linear_vel

float

0.05

Minimum linear velocity for cross-track control (m/s). Must be between 1e-4 and 1e2.

min_angular_vel

float

0.01

Minimum allowable angular velocity (rad/s). Must be between 0.0 and 1e9.

cross_track_gain

float

1.5

Gain for cross-track in the control law. Must be between 0.0 and 1e2.

max_angle_error

float

np.pi / 16

Maximum allowable angular error (rad). Must be between 1e-9 and π.

max_distance_error

float

0.1

Maximum allowable distance error (m). Must be between 1e-9 and 1e9.

usage Example#

Stanley algorithm can be used in the Controller component by setting ‘algorithm’ property or component config parameter. The Controller will configure Stanley algorithm using the default values of all the previous configuration parameters. To configure custom values of the parameters, a YAML file is passed to the component.

stanley.py#
from kompass.components import Controller, ControllerConfig
from kompass.robot import (
    AngularCtrlLimits,
    LinearCtrlLimits,
    RobotCtrlLimits,
    RobotGeometry,
    RobotType,
    RobotConfig
)
from kompass.control import ControllersID

# Setup your robot configuration
my_robot = RobotConfig(
    model_type=RobotType.ACKERMANN,
    geometry_type=RobotGeometry.Type.BOX,
    geometry_params=np.array([0.3, 0.3, 0.3]),
    ctrl_vx_limits=LinearCtrlLimits(max_vel=0.2, max_acc=1.5, max_decel=2.5),
    ctrl_omega_limits=AngularCtrlLimits(
        max_vel=0.4, max_acc=2.0, max_decel=2.0, max_steer=np.pi / 3)
)

# Set Stanley algorithm using the config class
controller_config = ControllerConfig(algorithm="Stanley")  # or ControllersID.STANLEY

# Set YAML config file
config_file = "my_config.yaml"

controller = Controller(component_name="my_controller",
                        config=controller_config,
                        config_file=config_file)

# algorithm can also be set using a property
controller.algorithm = ControllersID.STANLEY      # or "Stanley"
my_config.yaml#
my_controller:
  # Component config parameters
  loop_rate: 10.0
  control_time_step: 0.1
  ctrl_publish_type: 'Sequence'

  # Algorithm parameters under the algorithm name
  Stanley:
    cross_track_gain: 1.0
    heading_gain: 2.0