ModelRob: A Simulink Library for Model-Based Development ... · Modeling of Cartesian Space Motion Control of a Robot Manipulator Indranil Saha ModelRob 7/20. ... Created two ﬁxed-point

ModelRob: A Simulink Library for Model-BasedDevelopment of Robot Manipulators

Indranil Saha

Department of Computer ScienceUniversity of California Los Angeles

Joint work with Natarajan Shankar (SRI International)

Indranil Saha ModelRob 1/20

Applications of Robot Manipulators


Applications of Robot Manipulators

Many applications, including in some mission-criticalsystems, for example, spacecraft and in somelife-critical systems, for example, tele-surgical robots


Model-Based Development of Cyber-Physical Systems

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Model-Based Development of Cyber-Physical Systems

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Main activity is modeling, code generation is automatic


Robotics Toolbox [Corke96]

A comprehensive toolbox to model robot manipulators inSimulink

Modeling blocksets are developed in Matlab S-functions

Useful for Simulation

Production code generation is not possible


Objective

To generate code automatically for the robotmanipulator software from the model


Objective

To generate code automatically for the robotmanipulator software from the model

Need a library of Simulink blocks, blocks shoulduse only Simulink’s basic blocks


ModelRob Library

A library to model kinematics of a robot manipulator inSimulink

Useful for both Simulation and Code Generation

Generated C code for M7 Controller (SRI’s tele-surgicalrobot)

- above 5000 lines of code in a few seconds


Modeling of Cartesian Space Motion Control of aRobot Manipulator


Simulation Result


Conformance with Robotics Toolbox


Fixed-Point Implementation of Robot Software

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Fixed-point Modeling of M7 Controller

Created two fixed-point model for cartesian space motioncontrol of a robot manipulator: 8-bit model and 16-bitmodel

The end-effector still follows the trajectory, but with largererror

Error decreases as the number of bits increases


Simulation Results

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8-bitimplementation

16-bitimplementation


Cyber-Physical System Development Flow

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Limitations of Simulation

Simulation can find out bugs, but cannot guaranteecorrectness

Needs disciplined analysis approaches - formal verification


Cyber-Physical System Development Flow

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Two Step Verification Approach

Dimensional Consistency CheckingCheck if the Simulink model is well-formed with respect todimensionEnsures that the mathematical equations of the systemhave been captured correctly in the model

Functional VerificationVerification of functional properties of the system on themodelMakes sure that the system has been designed correctly

We present two toolsDimSim An automatic dimension checker for SimulinkSimprover A Simulink verifier through theorem proving


Verification Issues

A number of verification tools available for Simulink models

The tools do not support nonlinear arithmetic

Need to build the tools the can handle specificnonlinearities arisen in robot models


What Properties to Verify?

Two very intutive properties..

While moving the end-effector, no part of the robotmanipulator should go inside an unsafe region.

Eventually the end-effector follows the desired trajectorywithin certain specified error bound.


Future Work

Developing verification tools suitable for robot software

Extending the Library to support modeling of

- robot dynamics

- stationary robots, e.g., cylindrical, spherical and parallelrobots

- mobile robots, e.g., wheeled robots and legged robots


Thank You!!http://www.csl.sri.com/∼shankar/ModelRob.tar


Documents

ModelRob: A Simulink Library for Model-Based Development ... · Modeling of Cartesian Space Motion Control of a Robot Manipulator Indranil Saha ModelRob 7/20. ... Created two ﬁxed-point