Robotics Knowledge

Control.systems.can.be.broadly.classified.into.two.basic.categories:.open-loop.control.systems.and.closed- loop.control.systems..While.both.classes.of.systems.have.common.objectives.to.provide.a.desired.system. response,.they.differ.in.physical.configurations.as.well.as.in.performance..An.open-loop.control.system,. typically.shown.in.Figure.2.1,.utilizes.a.controller.or.control.actuator.in.order.to.obtain.the.desired.response. of.the.controlled.variable.y..The.controlled.variable.is.often.a.physical.variable.such.as.speed,.temperature,. position,.voltage,.or.pressure.associated.with.a.process.or.a.servomechanism.device..An.input.signal.or.com- mand.r.is.applied.to.the.controller.C(s),.whose.output.acts.as.the..actuating..signal e,.which.then.actuates.the. controlled.plant.G(s).to.drive.the.controlled.variable.y.toward.the.desired.value..The.external.disturbance,. or.noise.affecting.the.plant,.is.represented.in.the.figure.by.a.signal.n,.appearing.at.the.input.of.the.plant. An.example.of...

A mobile robot needs locomotion mechanisms that enable it to move unbounded through- out its environment. But there are a large variety of possible ways to move, and so the selec- tion of a robot’s approach to locomotion is an important aspect of mobile robot design. In the laboratory, there are research robots that can walk, jump, run, slide, skate, swim, fly, and, of course, roll. Most of these locomotion mechanisms have been inspired by their bio- logical counterparts (see figure 2.1). There is, however, one exception: the actively powered wheel is a human invention that achieves extremely high efficiency on flat ground. This mechanism is not completely for- eign to biological systems. Our bipedal walking system can be approximated by a rolling polygon, with sides equal in length to the span of the step (figure 2.2). As the step size decreases, the polygon approaches a circle or wheel. But nature did not develop a fully rotating, actively powered joint, which is the technology nec...

A.new.class.of.phenomena.has.recently.been.discovered.three.centuries.after.the.publication.of.Newton’s Principia.(1687).in.nonlinear.dynamics..New.concepts.and.terms.have.entered.the.vocabulary.to.replace. time. functions. and. frequency. spectra. in. describing. their. behavior,. e.g.,. chaos,. bifurcation,. fractal,. Lyapunov.exponent,.period.doubling,.Poincaré.map,.and.strange.attractor. Until.recently,.chaos.and.order.have.been.viewed.as.mutually.exclusive..Maxwell’s.equations.gov- ern.the.electromagnetic.phenomena;.Newton’s.laws.describe.the.processes.in.classical.mechanics,.etc.. They.represent.the.world.of.order,.which.is.predictable..Processes.were.called.chaotic.when.they.failed. to.obey.laws.and.they.were.unpredictable..Although.chaos.and.order.have.been.believed.to.be.quite. distinct.faces.of.our.world,.there.were.tricky.questions.to.be.answered..For.example,.knowing.all.the. laws.governing.our.global.weather,.we.are.unable.to.predict.it,.or.a.fluid.system.can.turn.easily.f...

Recently there has been a lot of discussion about futuristic wars between humans and robots, robots taking over the world and enslaving hu-mans. Movies like The Terminator, Star Wars, etc., have propogated these ideas faster than anything else. These movies are beautiful works of fi c-tion and present us with an interesting point of view to speculate. However, the truth is much different but equally as interesting as the fi ction. If you look around yourself you will see several machines and gizmos within your surroundings. When you use a simple pair of spectacles, do you become non-living? When an elderly person uses a hearing aid or a physically challenged person uses an artifi cial leg or arm do they become half machine? Yes, they do. Now we are rapidly moving toward an era where we will have chips embedded inside our bodies. Chips will communicate with our biological sensors and will help us in performing several activities more effi ciently. An artifi cial retina is almost at the fi n...

Spatial, rigid-body kinematics can be viewed as a com-parative study of different ways of representing the pose of a body. Translations and rotations, referred to in com-bination as rigid-body displacements, are also expressed with these representations. No one approach is optimal for all purposes, but the advantages of each can be lever-aged appropriately to facilitate the solution of different problems. The minimum number of coordinates required to locate a body in Euclidean space is six. Many represen-tations of spatial pose employ sets with superabundant coordinates in which auxiliary relationships exist among the coordinates. The number of independent auxiliary relationships is the difference between the number of coordinates in the set and six. This chapter and those that follow it make frequent use of coordinate reference frames or simply frames. A coordinate reference frame i consists of an origin, denoted Oi , and a triad of mutually orthogonal basis vectors, denoted ( ˆxi ˆy...