Simulators

The Ros Simulator is only used in simulation and, as the name already describes, is used to simulate the model dynamics for certain inputs and publishes measurements.

state_type: <pacejka_car|kinematic_car>
input_type: <pacejka_car|kinematic_car>

[process_noise]:
   <Noise Model>

sensors:
  sensor_names: List[<mocap|imu>] # <-- Must match provided sensor models
    <sensor model>
    [<sensor model>]
    [...]

initial_state: List[double] # 6 entries for pacejka, 4 for kinematic
initial_input: [double, double] # [steer_input, torque_input]

frequency: double # Hz, speed of simulator
input_delay: <double> # input delay in seconds
do_collision_checks: <true|false> # check if car drives out of bounds, if yes slows down velocity

Example

state_type: pacejka_car
input_type: pacejka_car

process_noise: # This can be uncommented to not have any process noise
  type: multivariate_gaussian
  seed: 42
  mean:
    value: [[0], [0], [0], [0], [0], [0]]

sensors:
  sensor_names: ["mocap"]
  mocap:
    R:
      value: [[0.001], [0.001], [0.001]]
      is_diag: true
    frequency: 200 # Hz
    key: mocap # optional, if not set us e name of sensor
    measurement_noise:
      type: multivariate_gaussian
    delay: 0.0

  # e.g. for IMU config
  # imu: 
  #   R:
  #     value: [[0.001], [0.001], [0.001]]
  #     is_diag: true
  #   frequency: 50 #Hz
  #   key: imu # optional, if not set us e name of sensor
  #   measurement_noise:
  #     type: multivariate_gaussian
  #     seed: 1
  #     mean:
  #       value: [[0], [0], [0]]
  #   delay: 0.0

initial_state: [0.15, -1.05, 0, 0.5, 0, 0]
initial_input: [0.0, 0.2]

frequency: 50 #Hz, speed of simulator

input_delay: 0.01 # input delay in seconds
do_collision_checks: true

ROS Information

Node Names	Description
ros_simulator	Runs the simulator

Launch File Arguments

Argument	Default	Description
simulator_config	$(find ros_simulator)/config/pacejka_car_simulator.yaml	Config to load for the Simulator.
control_input	control_input	Topic where the control input will be received.
mocap_topic	mocap	Topic where the motion capture measurements will be published.
imu_topic	imu	Topic where the imu measurements will be published.
imu_yaw_rate_topic	imu_yaw_rate	Topic where the imu yaw rate measurements will be published.
wheel_encoder_topic	wheel_encoders	Topic where the wheel encoder measurements will be published.
lighthouse_topic	lighthouse	Topic where the lighthouse measurement will be published.
gt_state_topic	gt_state	Topic where the ground truth state is published.

Subscribed Topics	Description
ros_simulator/control_input	Control input

Published Topics	Description
ros_simulator/gt_state	Ground truth state
ros_simulator/mocap	Motion capture measurements
ros_simulator/imu	Imu measurements
ros_simulator/wheel_encoders	Wheel encoder measurements
ros_simulator/lighthouse	Lighthouse measurements

Parameters	Description
/model/Q/is_diag	If True, the process noise covariance matrix of is given as its diagonal entries
/model/Q/value	Value of the process noise covariance matrix
/model/model_params/Bf	Front tire stiffness factor
/model/model_params/Br	Rear tire stiffness factor
/model/model_params/Cd0	Friction expansion 0th order coefficient
/model/model_params/Cd1	Friction expansion 1st order coefficient
/model/model_params/Cd2	Friction expansion 2nd order coefficient
/model/model_params/Cf	Front tire shape factor that controls the ‘stretching’ in the x direction
/model/model_params/Cm1	Model parameter
/model/model_params/Cm2	Model parameter
/model/model_params/Cr	Rear tire shape factor that controls the ‘stretching’ in the x direction
/model/model_params/Df	Peak value for front tire.
/model/model_params/Dr	Peak value for rear tire.
/model/model_params/I	Inertia
/model/model_params/lf	Length from center to front wheel
/model/model_params/lr	Length from center to rear wheel
/model/model_params/m	Mass of car
/model/model_params/gamma	Torque split between front and rear axle
/model/model_params/eps	Velocity at which the approximated slip angles are used to avoid singularities at zero velocity
/model/type	Model (e.g Pacejak)
/ros_simulator/do_collision_checks	If true, the simulator checks for track collision and sets the car velocity to a small, negative value.
/ros_simulator/frequency	Frequency at which the simulator runs
/ros_simulator/initial_input	Initial control input
/ros_simulator/initial_state	Initial state
/ros_simulator/input_delay	Input delay
/ros_simulator/input_type	Control input type
/ros_simulator/sensors/sensor_names	Name of sensor
/ros_simulator/sensors/mocap/R/is_diag	If True, the motion capture measurement noise covariance matrix is given as its diagonal entries
/ros_simulator/sensors/mocap/R/value	Value of the Motion capture measurement noise covariance matrix
/ros_simulator/sensors/mocap/delay	Delay of the Motion capture measurements
/ros_simulator/sensors/mocap/frequency	Frequency at which the Motion capture measurements are published
/ros_simulator/sensors/mocap/key	Key that identifies the Motion capture sensor
/ros_simulator/sensors/mocap/measurement_noise/type	Type of noise applied to the measurements
/ros_simulator/state_type	State type