Ros Estimators

The Ros Estimator node takes in a state measurement as well as a control input and outputs a state. It can be launch by executing

roslaunch ros_estimators default.launch

Visualizers

There is a generic car visualizer that visualizes the state estimate in the simulation. The user has the option to either just visualize the position, i.e. as a point, or the position as well as the orientation (as an arrow) by setting the parameter use_arrow in the estimator config file (estimator.yaml).

Showing estimated position and orientation

Example Configuration

# Visualization parameters for car_estimator_visualizer
visualizer:
  type: car_estimator_visualizer
  rate: 10

  # Visualizer specific  parameters
  frame_id: crs_frame # default
  namespace: car_estimate # default

  use_arrows: false # If true, use arrows to visualize yaw angle of estimate.

  # Color of the estimated position
  est_r: 0
  est_g: 0
  est_b: 0
  est_a: 1

  size_x: 0.05 # 0.07 for arrows
  size_y: 0.05 # 0.02 for arrows
  size_z: 0.05 # 0.02 for arrows

Specialized Visualizers

• EKF Visualizer
• MHE Visualizer

Component Registry

For a given estimator type set in the config (estimator.yaml), e.g. type: "discrete_ekf", the component registry will load the respective estimator. Each estimator type has its own file resolve_<estimator>in which the necessary parameters, dynamic and sensor models are loaded and the estimator returned.

The same goes for the visualizers and sensors, where in the file resolve_visualizers.cpp and resolve_sensor_models the correct visualizer and sensor models for the state estimator are loaded.

Launch file Arguments

The default.launch file accepts the following arguments:

Argument	Default	Description
input_topic	control_input	Topic where the control input will be published.
vicon_topic	vicon	Topic where the vicom measurement will be published.
imu_topic	imu	Topic where the imu measurement will be published.
imu_yaw_rate_topic	imu	Topic where the yaw rate of the imu measurement will be published.
wheel_encoder_topic	wheel_encoders	Topic where the wheel encoder measurement will be published.
lighthouse_topic	lighthouse	Topic where the lighthouse measurement will be published.
state_est_topic	estimation_node/best_state	Topic where the state estimate is published.
world_frame	world	Name of common frame for all objects (e.g. base for vicon measurements).
track_frame	world	Name of the frame where in which the car track origin is published.
update_track_transform	false	If true, continuously update the transformation between 'world_frame' and 'track_frame'. This allows to e.g. move the track during an experiment. If false, only use the first published transform for the whole experiment.