Robotics Simulator Intelligent Systems Lab

What is it ? Software framework - Simulating Robotics Algorithms

Objectives / High Level Features Generic – No physical environment assumptions 3D Visualization Extensible – Add new entities Open Source – Maintained on SourceForge Developed in C++ with MS Visual Studio 2008

Architecture Simulator 3D Visualization RobotEntities Environment Managers ObstacleEntities

Object Entities Both static objects (e.g. floor, obstacles) and dynamic objects are entities Entity has: Properties – A set of labeled string values These maintain the object’s state (position, shape) One property all entities have is a GUID A motion function called progress For dynamic objects, the actions / movement it performs

Simulation Flow Load Environment Estimate Frame Time Progress Entities Frame Stages: Preprocess Move Management Render Post-process

Serialized Simulation Environment Example

Typical Robot Progress Typical progress function contains: Save original robot state Evaluation of world state / sensors Modify transformation matrix Apply collision response, if necessary

3D World Space Each visible entity has a 4 x 4 transformation matrix Specifies position and orientation Matrix is usually modified by applying Translation and Rotation transforms Z - forward X - right Y - up x y z 1 Translation Transform c 0 s s 0 c Yaw Rotation Transform c=cos(a), s=sin(a)

Sensors Theoretically, any type of sensor can be implemented Currently implemented: Camera – Uses 3D visualization to generate image Can be placed in any position / orientation (synchronous) Laser distance sensor – Returns point of contact of first object along ray path (asynchronous)

Notifications Entities may generate events Entities may register to get notifications of events from other entities Examples: 3D Visualization registers to get all motion events An entity gets notification when an asynchronous sensor has a result value

Entity Software Structure Each entity type is a dynamic library (DLL) DLL exports a fixed set of functions: GetNameReturns name of entity type GetDescriptionA short description StartupInitialization if needed ShutdownCalled before DLL is unloaded CreateCreate a new entity instance GetIconPathPath to an icon image

Physics Physics rules can be implemented if needed Collision detection manager is in place All entities marked as collidable are checked In case of collision, both entities are ‘notified’

Communication A socket server is built into the simulator to allow an external program to control entities The external program can be on the same or different machine than the one running the simulation Message refer to entities using the entity GUID

Demos