MSRS - Critique on its Usability via a Path Planning Algorithm Implementation

George Markou & Ioannis Refanidis

University of Macedonia

Greece

Microsoft Robotics (1/2)• Microsoft Robotics Studio (MSRS) 1.0

– Originally available in late 2006

• MSRS 1.5 Refresh – Available in late 2007– Version we used to implement our experiments

• Microsoft Robotics Developer Studio (MRDS) 2008– Current version (Since April 2008)

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Microsoft Robotics (2/2)Features include:– Microsoft Visual Simulation Environment (VSE)

• 3D physics-based virtual environments• User can create / import 3-dimensional meshes into MSRS’ simulation

environment

– Support for multiple programming languages• C#, C++, VB.NET, Iron Python• Visual Programming Language (VPL)

– Built-in support for multiple robots• LEGO MINDSTORMS NXT, iRobot Create, MobileRobots Pioneer P3DX, etc.

– Concurrency and Coordination Runtime (CCR)• “manages asynchronous operations, exploits parallel hardware and deals

with concurrency and partial failure”

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Related WorkWhat others say:

– Lots of technological solutions to common robotic field problems : e.g. VPL & concurrency

control &efficient distributed message passing. (Jackson J, 2007)– Usefulness in academic environment:

• Link between language syntax already known to students and unfamiliar robotics semantics• Satisfied with the available features of the program and its support (Workman K & Elzer S,

2009))– Will force other platforms to develop their competitive products so as to offer similar

capabilities (Tick J, 2006)

– Evident limitations: e.g. integration with low level processors (Jackson J, 2007)

– Usefulness in high school environment:• Main disadvantage: Visual programming language used requires detailed knowledge of an

imperative programming language (Tsai W T et al., 2007)

Our critique?

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Robotics Platforms Comparison

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  MSRS 1.5 MobileRobots Skilligent Orocos Player Project Urbi/ Webots

Open Source No No No Yes Yes Parts of Urbi

Free of Charge Express Edition No No Yes Yes No

Windows/ Linux Yes/ No Yes/ Yes Yes/ Yes No/ Yes No/ Yes Yes/ Yes

Other OS No No No No Yes Yes

Distributed Services Yes No Yes No Limited Yes

Drag-and-Drop IDE Yes No No No No Yes

Object Recognition No No Yes No No No

Localization No Yes Yes No No No

Learning/ SocialInteraction

No No Yes No No No

Simulation Environment Yes Yes No No Yes Yes

Reusable Service Blocks Yes Yes Yes Yes No Yes

Real-Time No No No Yes No No

Maze Domain (1/2)• Simulated Maze

– Originally created using MSRS 1.5 Refresh– Migrated to MRDS 2008

• Creating very realistic environment: not suited for novices– Professional examples: see SimplySim (www.simplysim.net)

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Maze Domain (1/2)• Our environment

– Simpler – Based on the “MazeSimulator” project (Trevor Taylor -

http://www.promrds.com/Downloads.htm) – Gridworld of size 7×7– Nodes can randomly alternate their status between blocked & unblocked

(abstraction of the Robocup Rescue Simulator Competition - http://www.robocuprescue.org)

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Maze Domain (2/2)• Robot

– Pioneer 3DX with mounted Sick Laser Range Finder (LRF) LM200

• Movement of the robot:– Moves in a straight line for a distance equal to the length of a node.– Decides, based on the planning algorithm, if a turn is necessary– Executes the turn (in angles which are multiple of 90°)

• Using LRF, the robot builds a tri-color map of the environment– White color: Free space – Black color : Laser hit an obstacle– Grey color: Non explored part of the maze

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Implementation• Implemented the backwards version of the Lifelong Planning

algorithm (LPA*) (Koenig et al., 2004)– Combination of heuristic (A*) & incremental algorithm

(DynamicSWSF-FP)– Able to repeatedly find a shortest path between two given

vertexes in a dynamic environment

• Dynamic Environment: Blocking / unblocking a maximum of two nodes.

• Use of C#

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Critique (1/2)Why not VPL?

• Preference towards languages related to our previous knowledge (in our case C#)• Diagrams tend to become exceedingly large as program’s complexity increases• Limited support for arbitrary user-defined data types • Built-in support:

– Control flow: “if statements”– Collection of items: lists– Recursion and arrays are not natively supported

Why VPL?

• Graphical “drag-and-drop” programming– Best suited for novice users

• Creation of a program by “orchestrating activities” == connecting activity blocks• Most useful as a tool, especially if one is not familiar with MSRS’ environment

– Easily create the skeleton of a basic program by wiring activities to each other & automatically generating C# code through it

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Critique (2/2)• CCR:

– Handles the required messaging and orchestration efficiently – Instead of writing complex code to coordinate sensors & motors functioning

simultaneously

• Simulation environment– Served our functional needs– Aesthetically appealing

• MSRS 1.5 Refresh: Extensive features & capabilities

• Potentially establish it as the field’s standard• Major advantage: Vast economical & commercial support a company like Microsoft can

provide for it

Several minor or major difficulties• Major: Unexpected termination depending on the machine it was executed on• Most attributed to small life cycle of the product migration to MRDS resolved them• Such problems could discourage researchers/educators from relying on it

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Future Work• Different environment

– Induce changes to it more than once– Coordinate MSRS’s services to communicate automatically every

time a change occurs

• More efficient, semi-quantitative evaluation– Develop structured questionnaire– Ask two groups of students to fill them out– Each of them will implement a similar robotics project in MSRS &

another robotic platform

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Thank you!

• Comments? Questions?

• Contact us at: gmarkou/ yrefanid@uom.gr

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