Simulation as a tool to speed up Simulation as a tool to speed up developing and testingdeveloping and testing

G. Randelli, D. Calisi

Ups…

What is a Robotic Simulator?

A brief definition:

“A robotics simulator is used to create embedded applications for a specific (or not) robot without depending physically on the actual robot.”

“The best simulator does not have to resemble reality in the most accurate way. The power of a simulator is to fit to our needs.” (Elron, 1983)

Why do we need simulation?

Globally, there are one million industrial robot in service, as well as six hundred thousand household robots. (source: United Nations Economic Commission, 2004)

But...

– Robots can be damaged

– High Costs & Low Budgets

– Tests Repeatability

– Environmental Factors

Simulators can get rid of these problems but can raise up new ones

Simulation advantages (1)Simulation advantages (1)

“Simulations provide students with experience that may be difficult or impossible to obtain in everyday life”

(Bork, 1981) Cost

No cost for any robot or equipment No risk of damage, no hardware consumption, no maintenance No human risk

Time Simulations can be run in parallel You do not have to recharge the batteries (yes, it’s a waste of

time) Sometimes, simulation can be run faster than real-time

Simulation advantages (2)Simulation advantages (2)

“Simulations provide students with experience that may be difficult or impossible to obtain in everyday life”

(Bork, 1981) Experiments

We can reproduce whatever environment and situation we want, as complex and as dangerous as we desire

Experimental replicability Scalability issues We can simulate robots and sensors that we do not have, or

that do not exist at all (yet) Con be used in learning sessions (many repetitions of the same

task), at least in a preliminary step (afterwards you would perform learning sessions on the real robot)

Simulation disavantagesSimulation disavantages

Simulation development is not effortless Physic laws simulation is not always realistic Simulation is not reality, thus a working

simulated robot does not imply a working real robot

Errors and noises simulation Simulations can introduce problems not present

in the reality

How an OpenRDK agent interact with a simulatorHow an OpenRDK agent interact with a simulator

robot

laserClient

/robot/odometryPose

/robot/speed

/laserClient/laserData

Robot driver

Laser driver

simClient

/simClient/odometryPose

/simClient/speed

/simClient/laserData

Simulator

Evaluation Criteria for a Robotic Simulator

• Physical Fidelity: the extent to which the virtual environment emulates the real world

– High physical fidelity can enhance the learning process of the experiment attender

• Functional Fidelity: the degree to which the simulation acts like the operational equipment in reacting to the tasks executed by the trainee

• Ease of Development: environment creation ease, simulator changes ease, available documentation

• Cost: a simulator should be little time consuming

Commercial Simulators

Webots, Microsoft Robotics Studio, RoboLogix, anyKode Marilou

Open Source Simulators

Player/Stage/Gazebo, MissionLab, SimRobot, FlightGear, USARSim

Questions?Questions?

Questions?