Configure robots and obstacles#

To effectively simulate robots within your environment, you need to define and configure various robot parameters.

Robot Configuration Parameters#

Each robot in the simulation is defined by a set of parameters in a YAML configuration file. Below is a simple example of a robot configuration:

The python script and YAML configuration file:

import irsim

env = irsim.make('robot_world.yaml')

for i in range(1000):

    env.step()
    env.render(0.05)

    if env.done():
        break

env.end()

world:
  height: 10 
  width: 10   

robot:
  kinematics: {name: 'diff'}  
  shape: {name: 'circle', radius: 0.2}  
  state: [1, 1, 0]  
  goal: [9, 9, 0] 
  color: 'g'
  plot:
    show_trajectory: True
    show_goal: True

Important Parameters Explained#

  • kinematics: Defines the movement model of the robot. Name options include 'omni', 'omni_angular', 'diff', and 'acker'.

    • 'omni': Omnidirectional wheels allowing movement in all directions (no orientation control).

    • 'omni_angular': Omnidirectional with yaw rate control (can translate and rotate independently).

    • 'diff': Differential drive allowing movement forward/backward and rotation.

    • 'acker': Ackermann steering, typical for car-like robots.

Kinematics Comparison:

Kinematics

Control Input

Typical Use

Can Rotate in Place?

omni

[forward, lateral] - body-frame velocity

Holonomic robots, drones

βœ— No

omni_angular

[forward, lateral, yaw_rate] - body-frame velocity + yaw

Holonomic robots with rotation

βœ“ Yes

diff

[v, Ο‰] - linear & angular velocity

Two-wheeled robots

βœ“ Yes

acker

[v, Ο†] - linear velocity & steering angle

Cars, car-like robots

βœ— No

  • shape: Specifies the physical shape and size of the robot. Name options include 'circle', 'rectangle', 'polygon', and linestring.

    • circle: A circular robot with a specified radius.

    • rectangle: A rectangular robot with specified length and width.

    • polygon: A polygonal robot.

    • linestring: list of lines.

  • state: Defines the initial position and orientation of the robot in the environment.

  • goal: Specifies the target position and orientation for the robot.

  • plot (optional): Specifies the visualization settings for the robot. See plot() for more details.

The robot has a default behavior of moving from its initial position to the goal position directly (dash) if the kinematics is set.

Explanation#

  • env.step(): Advances the simulation by one time step. You can input your control commands here by env.step(velocity) to run your own control algorithm. velocity is associated with the kinematics of the robot. See step() for more details.

  • env.render(0.05): Renders the current state of the environment with a 0.05-second delay between frames. See render() for more details.

  • env.done(): Checks whether the simulation conditions to terminate have been met. Such as reaching the goal or a collision. See done() for more details.

  • env.end(): Ensures that the simulation is terminated gracefully, releasing any resources or handles. Provides a clean exit. See end() for more details.

Note

The rda_planner is a case of using the env.step(velocity) to run your own control algorithm.

Note

You can add Gaussian noise on the kinematics of the robot and obstacle by setting the noise to be True in parameter in the kinematics dictionary. See kinematics for more details.

Obstacle Configuration Parameters#

The parameters of obstacles in the simulation are similar to those of robots. Below is an example of adding various obstacles to the yaml configuration file, and run the same python script as above.


import irsim

env = irsim.make('robot_world.yaml')

for i in range(1000):

    env.step()
    env.render(0.05)

    if env.done():
        break

env.end()

world:
  height: 10 
  width: 10   

robot:
  kinematics: {name: 'diff'}  
  shape: {name: 'circle', radius: 0.2}  
  state: [1, 1, 0]  
  goal: [9, 9, 0] 
  color: 'g'
  plot:
    show_trajectory: True
    show_goal: True

obstacle:
  - shape: {name: 'circle', radius: 1.0}  # radius
    state: [5, 5, 0]  
  
  - shape: {name: 'rectangle', length: 1.5, width: 1.2}  # length, width
    state: [6, 5, 1] 

  - shape: {name: 'linestring', vertices: [[5, 5], [4, 0], [1, 6]] }  # vertices
    state: [0, 0, 0] 
    unobstructed: True

  - shape:
      name: 'polygon'
      vertices: 
        - [4.5, 4.5]
        - [5.5, 4.5]
        - [5.5, 5.5]
        - [4.5, 5.5]
Select Parameters

Important Parameters Explained#

  • unobstructed: If True, there is no collision detection with the object.

Note

Robot vs Obstacle - Key Differences:

Parameter

Robot Default

Obstacle Default

role

"robot"

"obstacle"

color

Varies

"k" (black)

kinematics

User-defined

None (static)

behavior

{name: 'dash'} if kinematics set

None (static)

Configuration Tips:

  • Without kinematics, obstacles remain stationary

  • Add kinematics + behavior to create moving obstacles

  • Use - to define each new robot/obstacle in the list

Warning

Please make sure that the obstacles are not placed in the initial position of the robot. Otherwise, the robot will collide with the obstacles at the beginning of the simulation.

Advanced Configurations for Multiple Robots and Obstacles#

To simulate multiple robots and obstacles within the same environment, simply add the number and distribution of robots and obstacles to the configuration file. Below is an example of a configuration file with multiple robots and obstacles:


import irsim

env = irsim.make('robot_world.yaml')

for i in range(1000):

    env.step()
    env.render(0.05)

    if env.done():
        break

env.end()

world:
  height: 10  # the height of the world
  width: 10   # the width of the world

robot:
  - number: 2
    distribution: {name: 'manual'}
    kinematics: {name: 'diff'}
    shape: 
      - {name: 'circle', radius: 0.2}  # radius
    state: 
      - [1, 1, 0]  
      - [2, 1, 0]
    goal:
      - [9, 9, 0] 
      - [9, 2, 0]
    color: 
      - 'royalblue'
      - 'red'
  
  - number: 4
    distribution: {name: 'random'}
    kinematics: {name: 'diff'}
    shape: 
      - {name: 'circle', radius: 0.2}  # radius
    color: 
      - 'pink'


obstacle:
  - number: 4
    distribution: {name: 'manual'}
    state: [[4, 8], [1, 3], [1, 0], [5, 2]]
    shape:
      - {name: 'circle', radius: 0.2}  # radius
      - {name: 'circle', radius: 0.1}  # radius
    color: 'k'

Note

  • The distribution parameter specifies how the robots and obstacles are distributed within the environment. Options include 'manual' and 'random'. Details are provided in the YAML Configuration

Select Parameters