m-a. leblanc pierre sicardrequire time derivation of measured speed (or acceleration measurement)....

Workshop EMR’ 09Trois-RivièresSeptember2009

« Modelling and control usingEnergetic Macroscopic Representation »

EMREMR AND AND IINVERSIONNVERSION--BBASED ASED CCONTROL OF A ONTROL OF A VVIRTUAL IRTUAL RREALITY EALITY

BBICYCLE ICYCLE TTRAINERRAINERM-A. LeblancPierre Sicard

Université du Québec à Trois-Rivières, Canada

EMREMR AND AND II--BCBC OF AOF A VVIRTUAL IRTUAL RREALITY EALITY BBICYCLE ICYCLE TTRAINERRAINER

EMR’09, Trois-Rivières, September 20092Introduction

Let the cyclist feel the road…when he wasn’t there!

• In virtual reality training, we want the cyclist to feel the same effects on a stationary bike as he would on the road.

• The virtual reality training system consists of a bicycletrainer base, a data base from a virtual or real road ride and an electrical drive for loading and energy recovery.

• The EMR is use to clarify the representation of various models used for the environment, cyclist force estimation and control design.


EMR’09, Trois-Rivières, September 20093Contents

1/ Problem statement

2/ EMR modeling of the dynamic braking system

3/ Reference signal for emulation

4/ Inversion-based control

5/ Results

6/ Conclusion



PPROBLEM ROBLEM SSTATEMENTTATEMENT


EMR’09, Trois-Rivières, September 20095Problem statement

The cyclist should feel effects from:• Mass Inertia• Slope• Aerodynamics• Wheel-road friction



The behaviour of the virtual trainer should be independent of the bicycle being used and how it is being used: we shall consider a model at the interface between the wheels and the road.



A passive braking system may be used, with some restrictions.

To provide greater opportunities for virtual training and for educational purposes, an active loading system will be used, providing capabilities to use the produced energy or to connect the trainer to a power network.



EMREMR MMODELING OF THE ODELING OF THE DDYNAMIC YNAMIC

BBRAKING RAKING SSYSTEMYSTEM


EMR’09, Trois-Rivières, September 20099EMR modeling of the dynamic braking system

• A dc machine (generator) is used for loading the bicycle.• The bicycle is coupled to the generator through a simple

transmission (roller).


EMR’09, Trois-Rivières, September 200910EMR modeling of the dynamic braking system

• Power converters are used to control the load and to interface the trainer to an electric load or a power network.



RREFERENCEEFERENCE SSIGNAL IGNAL

FORFOR EEMULATIONMULATION


EMR’09, Trois-Rivières, September 200912Reference signal for emulation

We want to choose a control structure and measurements so that the virtual trainer reproduces the effects of the environment and cyclist (mass, aerodynamics …).


EMR’09, Trois-Rivières, September 200913Reference signal for emulation

What should be the reference input for emulation?

• Load force as a reference input: – An apparent natural choice to impose aerodynamic and

gravity effects.– Inclusion of mass-inertia effect in the reference signal would

require time derivation of measured speed (or acceleration measurement).

• Bicycle velocity as a reference input:– Maintaining the velocity in the trainer close to the model

velocity, with high dynamics, implies proper loading.– The reference velocity

is obtained directly from the cyclist-environment model.

– This option is chosen.



IINVERSIONNVERSION--BBASED ASED CCONTROLONTROL

EMR’09, Trois-Rivières, September 200915


Inversion-based control

• At this point, we assume that the applied force is measured.

• The environment model reproduces the real system with the cyclist’s and bicycle mass-inertia, aerodynamics, friction and slope along a predefined trajectory.

• In the following, we will only consider the load emulation control and assume that the dc-bus voltage is well controlled.




Using inversion-based control we deduce the control structure

To obtain a practical control structure:

• Neglect electromotive force E• Roller torque can be estimated from applied force (Force)• Applied force can also be estimated or observed to avoid

using expensive sensors.




Only classical measurements are required, i.e. current and machine speed.

Applied force estimation is obtained by using the models of the bike trainer and machine.



RRESULTSESULTS


EMR’09, Trois-Rivières, September 200920Results

Simulation results were obtained with SimulinkTM for the emulation system using data from the experimental system under development.

Characteristics of applied force profile: low frequency cyclic force.

Applied force

Estimated force

Time

Step response of the force estimator


EMR’09, Trois-Rivières, September 200921Results

Desired velocity

Simulated velocity

Applied force

Estimated force

Time

Simulation responses to a variation of slope and to a variation of applied force:

• applied force is estimated accurately• velocity of the trainer tracks

the emulation model velocity.


« Modelling and control usingEnergetic Macroscopic Representation »CCONCLUSIONONCLUSION

EMR provides a convenient and useful framework to describe and to define inverse-based control of electromechanical systems.

EMR proved very useful to clarify the control problem and to select a control strategy, including a convenient and efficient way to generate

the reference input and to define a partial state observer.

A relatively complex system, including its control, can be explained simply to non experts.



The virtual reality bicycle trainer is under development.

It will be used for undergraduate and graduate level training and for demonstration purposes.

Application:



Energy management issues : The dc-bus voltage can be maintained to the desired value only if power balance is achieved:

• External load or a braking resistor must dissipate the produced energy to avoid overvoltage;

• If produced power is smaller than losses, dc-bus voltage cannot be maintained unless energy storage or a connection to the power grid is used;

• Without energy storage or a connection to the power grid, loads that require a stable or fixed voltage cannot be fed by this system;

• Energy storage or a connection to the power grid, and a bidirectional power converter to interface the dc-machine, are required to reproduce coasting and going downhill conditions.

These issues are considered in implementation and for future work.


« Modelling and control usingEnergetic Macroscopic Representation »RREFERENCESEFERENCES

M-A. Leblanc, “Émulation de charge (Projet Vélo)”,Rapport de projet d’activités de synthèse en génieélectrique, Département de génie électrique et génie informatique, Université du Québec à Trois-Rivières, Mai 2009.

M-A. Leblanc, “Conception et mise en oeuvre d’un système d’entraînement virtuel pour cyclistes”,Rapportde stage en génie électrique, Département de génie électrique et génie informatique, Université du Québec à Trois-Rivières, Septembre 2009.

Seabury et al., Ergonomics, 1977, 20, pages : 491-498.

m-a. leblanc pierre sicardrequire time derivation of measured speed (or acceleration measurement)....

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