L'Agilité Comme une Performance Métrique Dans le Sport Robotisé.

From M.SPIESER under the supervision of J.BAILLIEUL

Abstract: This paper examines how and why the agility can be used as a performance metric in

robotic athletics according to recent research and some experiments with a Dubins vehicle like

robot. The main focus is to find a way to value the agility in order to represent the global

performance of a robot which can move as a Dubins vehicle in a specific situation.

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Introduction

Nowadays robots are used to accomplish human

tasks faster and/or better and also tasks that can not

be accomplished by a human being. A part of the

robotic application field is the sports, and according

to the artificial intelligence progress of the last

decade we can easily guess that robots will be able

to compete against human in a few years. As we

measure the performance of human athletes it is

interesting and feasible in most cases to measure a

robot's performance. The speed, the data-rate, the

response time, the precision and many other

performance metrics can be measured. These metrics

measure the varied components of agility and their

values in aggregate indicate how well the robot may

be expected to perform on various tasks. In order to

illustrate the discussion, we will use examples with a

defined context for the whole paper. A dubins

vehicle like robot (m3pi by Pololu) following a path

with different curves and turns, represented by a line

made of electrical tape with a certain thinness.

The paper is organized as follows. We will first

briefly introduce the term agility and how it can be

defined in a robotic context. In parts 2, 3, 4 and 5 we

will describe the agility of a robot with different

experiments. In the part 6 we will try to value the

agility of a robot in two specific situations and then

give a conclusion.

The agility is a very common term which includes

many aspects according to the field in which it is

used.

Literal definition of “agility”:

The agility is defined in the literature as: “The power

for an entity to handles change well.”[a]. So the first

idea covered by the term “Agility” is the ability to

handle changes well, and according to many other

definitions, it also covers the quickness and

efficiency of these changes.

Sports definitions of “agility”:

In the sports field, agility is defined as the ability to

react well to an event while under control. The

agility is often defined as “a complex combination

of qualities like balance, coordination, speed,

reflexes, strength, and endurance” [b].

All these bring us to a global definition which can be

applied in different fields including robotic athletics:

“Agility is the ability to change operating modes

quickly while maintaining all operational

constraints, according to a changing context and in

order to accomplish a defined task.”

Feedback impact

In a 2004 paper of Professor J. Baillieul about

“Data-rate requirements for nonlinear feedback

control” [1] they considered the problem of finding

the minimum data-rate at which sensor data must be

acquired in order to make it possible to control a

mobile robot to follow a prescribed path within a

prescribed error bound, in which we can find the

idea of agility by the link between data-rate and

control. In an other paper of Professor J. Baillieul,

about “Data-rate problems in feedback stabilization

of drift-free nonlinear control systems” [2], they

discussed how the system performance changes if

feedback laws of a moving vehicle are implemented

over data-rate constrained feedback channels. And as

in the previous paper we notice the impact of the

robots data-rate on the global performance of the

robot to accomplish a specific task. In our

experiments (1) we have reached the limit of the

feedback precision.

Experiment (1)

In order to solve a maze made of electrical black

tape, we have used the “Left hand on the wall”

algorithm [c] and in addition to that we would map

AGILITY AS A PERFORMANCE METRIC IN ROBOTIC ATHLETICS

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