Technology & Engineering
Kinematics Engineering
Kinematics engineering involves the study of motion, including the position, velocity, and acceleration of objects. It focuses on understanding and analyzing the movement of various mechanical systems, such as robots, vehicles, and machinery. By applying principles of physics and mathematics, kinematics engineering plays a crucial role in designing and optimizing the performance of these systems.
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7 Key excerpts on "Kinematics Engineering"
eBook - PDF- David F. Rogers(Author)
- 2016(Publication Date)
- Pergamon(Publisher)
The subject of kinematics provides a good example. Between 1940 and 1960 the availability of drafting tables and good drawing instruments promoted the development of graphical solution techniques for obtaining the displacement, velocity, and acceleration of mechanical com-ponents. Many of these techniques are still in use today [1]. The scientific and mathematical emphasis during the past 20 years has resulted in a vector analysis approach to kinematic analysis in most engineering curricula [2]. Both the graphical and vector analysis methods lead to the determination of instantaneous kinematic values for a particular configuration of the device under study. They will continue to provide valuable design tools for the engineer. Computer graphics makes feasible the use of complete kinematic motion curves for describing the behavior of mechanical components. This provides the option of observing the behavior of a mechan-ism over a complete cycle of operation, rather than at only a few instantaneous positions. The generation of motion curves may require a change in the manner in which the fundamental subject of kinematics is presented to undergraduate engineering students. The purpose of this paper is to illustrate some of the new options available to educators in engineering and physics which are feasible using low cost computer graphics. K I N E M A T I C S Kinematics, the study of motion in terms of displacement, velocity, and acceleration is fundamental to understanding modern technology. All components of a device in motion are treated as rigid members, and no concern is given to the forces which cause the motion. Kinematics is the foundation for later study in dynamics, vibrations, and machine design where forces and deflections are con-sidered. As higher speeds are encountered and energy efficient designs become more critical, a com-plete description of kinematic behavior will often be needed for proper analysis.
eBook - ePub- D. Gordon E. Robertson, Graham E. Caldwell, Joseph Hamill, Gary Kamen, Saunders Whittlesey(Authors)
- 2013(Publication Date)
- Human Kinetics(Publisher)
PART IKINEMATICSKinematics is the study of motion without regard to causes. Studying human motion in the past was a time-consuming, laborious, and expensive task because cinematography was employed and manual methods were needed to extract the trajectories of body parts from the film. Advances in technology have automated much of the processes of capturing motion data electronically and then extracting the two- or three-dimensional trajectories. Such technology is now commonplace in the motion picture industry, but biomechanists use additional software to obtain time derivatives of the various trajectories or combine the trajectories to reconstruct the motions of body segments and joints so that differences in motion patterns can be readily identified. Kinematics is also the first step to analyses by inverse dynamics (covered in part II ) that estimate the causes of the motion. In this part, chapter 1 outlines how to record two-dimensional kinematics electronically, photographically, and videographically and how to extract digital data from the recordings. Chapter 2 outlines the additional mathematics and processing needed for three-dimensional kinematics. Note that chapter 12 outlines data smoothing techniques that are also important to the valid processing of kinematics, particularly accelerations. Several of the appendixes also have information concerning electronics (appendix C ) and mathematical principles (appendixes D and E) that are required for data collection and analysis in kinematics. Note that text in boldface is a concept described in the glossary at the end of the book.
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Chapter 1Planar KinematicsD. Gordon E. Robertson and Graham E. CaldwellK inematics
eBook - ePub- Jitendra R. Raol, Jatinder Singh(Authors)
- 2023(Publication Date)
- CRC Press(Publisher)
2 Engineering DynamicsDOI: 10.1201/9781003293514-32.1 Introduction
This chapter gives the reader an insight into the various aspects of engineering dynamics. The subject of engineering dynamics is a blend of physics, applied mathematics, basic logic, and computational methods. An airplane is considered as a dynamic system, and hence, many principles and concepts of engineering dynamics are directly applicable to the study of aircraft flight mechanics–flight dynamics. Important aspects here are the use of the tools that describe the motion and solve the equations of motion of the vehicle, wherein the kinematics of a particle or a rigid body supports the laws of dynamics. The concerned scientists and engineers are interested in studying the movements of such bodies on Earth, in atmosphere, and in space and are also interested in predicting their behavior for longer time spans. Such an understanding would help them design, develop, modify, and use these vehicles for their intended purposes. The basic study actually starts with the vector mechanics algebra; however, it is presupposed to have been studied by the readers at the level of first two semesters’ course level in mathematics. The basic vector calculus can be easily used to derive the formulae for velocity and acceleration. The Newtonian mechanics plays very important role in the study of flight mechanics as dealt in Chapter 3 .The kinematical description can be understood by using either extrinsic or intrinsic coordinates: The former means that the description is extrinsic to the knowledge of the path followed by the point (rectangular Cartesian coordinates), and the latter means that the description uses the knowledge of the path. In the Cartesian coordinates, the position is known in terms of the distances measured along the three mutually orthogonal straight lines that represent reference directions. In the intrinsic coordinates, the unit vectors are defined in terms of the properties of the path, and these coordinates are known as path variables; alternatively, this description is also known as tangent and normal components. The fundamental variable for a denoted path is the arc length ‘s’ along a curve, measured from some starting point A to the point of interest, B. We also know that because ‘s’ changes with time, the position is an implicit function of time; this also means that the position is a vector function of the arc length. The velocity and acceleration are oriented parallel to the straight path. However, acceleration will not be parallel to the velocity for a smooth curvilinear path, unlesss ˙= 0
- John J. Uicker, Bahram Ravani, Pradip N. Sheth(Authors)
- 2013(Publication Date)
- Cambridge University Press(Publisher)
The branch of scientific analysis that deals with motions and forces in a mechan- ical system is called mechanics. As shown in Figure 1.1, it is made up of two parts, called statics and dynamics. Statics deals with the analysis of stationary systems, that is, those in which time is not a factor. Dynamics, on the other hand, deals with systems that change with time. 1.2 Multibody Systems and Mechanisms 3 Dynamics is also made up of two major disciplines. The great Swiss mathemati- cian, Leonhard Euler (1707–83), was the first to distinguish these [2]: The investigation of the motion of a rigid body may be conveniently separated into two parts, the one geometrical, the other mechanical. In the first part, the transference of the body from a given position to any other position must be investigated without respect to the causes of the motion, and must be represented by analytical formulae which will define the position of each point of the body after the transference with respect to its initial placement. This investigation will therefore be referable solely to geometry, or rather to stereotomy [the art of stone-cutting]. It is clear that by the separation of this part of the question from the other, which belongs properly to Mechanics, the determination of the motion from dynamic principles will be made much easier than if the two parts were undertaken conjointly. These two aspects of dynamics were later recognized as the distinct sciences of kinematics and kinetics, which treat the motion and the forces producing it, respec- tively. Kinematics was first defined as a separate study by the French mathemati- cian and physicist, Andr ´ e Marie Amp ` ere (1775–1836). He chose the French name cin´ ematique from the Greek word κ iνημα (kinema), meaning motion [1]. An inter- esting narrative on the history of kinematics is found in [3, pp. 1–27].
- Zhijun Li, Shuzhi Sam Ge(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
2 Kinematics and Dynamics CONTENTS 2.1 Introduction ............................................................. 17 2.2 Kinematics of Mobile Platform .......................................... 19 2.2.1 Differential-driven Mobile Platform ............................. 19 2.2.2 Car-like Mobile Platform ........................................ 23 2.3 Kinematics of Robotic Manipulators .................................... 24 2.4 Dynamics of Mobile Manipulators ...................................... 27 2.4.1 Lagrange-Euler Equations ....................................... 28 2.4.2 Kinetic Energy .................................................. 31 2.4.3 Potential Energy ................................................. 32 2.4.4 Lagrangian Equations ........................................... 32 2.4.5 Properties of Dynamic Equations ............................... 34 2.5 Dynamics in Cartesian Space ........................................... 36 2.6 Conclusion ............................................................... 39 2.1 Introduction Kinematics are the velocity relationships relating the linear and angular ve-locities of the task space end-effector to the joint space, while dynamics are concerned with the relationship between the forces acting on them and the positions, the velocities and the accelerations they produce. Mathematically, the forward kinematic equations define a function between the task space and the joint space. The velocity relationships are then deter-mined by the Jacobian which is a matrix that can be thought of as the vector version of the ordinary derivative of a scalar function. The Jacobian is one of the most important quantities in the analysis and control of robot motion. It arises in virtually every aspect of robotic manipulation: in the planning and execution of smooth trajectories, in the determination of singular con-17
eBook - ePubIntroduction to Mechanism Design
with Computer Applications
- Eric Constans, Karl B. Dyer(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
1Introduction to Kinematics
1.1 Introduction to Mechanical Design
The subject of this textbook is mechanical design and analysis. While most people have at least a vague idea of what the word “design” means, in this text we are mainly interested in two definitions [1 ]:Design: transitive verb 1. To make preliminary sketches of; sketch a pattern or outline for; plan. 2. To plan and carry out, esp. by artistic arrangement or in a skillful way. … intransitive verb 8. the arrangement of parts, details, form, color, etc. so as to produce a complete and artistic unitThe goal of the text is to give the reader a set of computational tools to design and analyze mechanisms to achieve specific goals. A mechanism is a collection of links and joints designed in such a way as to create a desired motion output. One link of a mechanism is “grounded,” that is, fixed to some reference frame, and we are commonly interested in finding the motion of the remaining links. Some examples of mechanisms are windshield wiper blades, the crankshaft/connecting rod/piston assembly in a car engine, certain types of hinges, mechanical watches and clocks, etc. Another excellent example of a mechanism, or linkage, is the human body. Each segment of the body can be modeled as a link, and the segments are connected through pin joints (the elbow) or spherical joints (the shoulder). By modeling the body in this way, biomechanical engineers can deduce the forces and moments present at the joints by analyzing the motion of the body with motion capture techniques.Scientists, mathematicians, and engineers have studied mechanisms since the 1700s. Until very recently, all mechanism analysis was performed graphically, that is, with drafting tools. These tools have been superseded in modern times by computational tools such as CAD software, which make it possible to analyze several trial designs very quickly to find a solution. Computers have also made “linkage design optimization” possible; that is, finding the dimensions of a linkage that traces out a desired path.
eBook - PDF- Philip Dyke, Roger Whitworth(Authors)
- 2017(Publication Date)
- Red Globe Press(Publisher)
CHAPTER 1 Kinematics 1.1 Introduction The study of the motion of bodies requires a structured understanding of the fundamental quantities of displacement and time. This study is called kine-matics and it will provide a basis for later modelling in other branches of mechanics. From time and displacement, we derive the quantities velocity and acceleration. Displacement, velocity and acceleration are vector quantities and can be expressed in an algebraic vector form. Not surprisingly, therefore, the study of vectors is crucial to the study of kinematics and indeed of all mechanics. We shall start our study by considering some kinematic quantities which may already be familiar. Everyday language provides us with an intuitive compre-hension of these quantities, but in some cases this familiarity can lead to serious misunderstanding, particularly where vectors are concerned. Here is an illustrative example. When a car is travelling along a road, and the speedometer reads an unchanging 30 km per hour, the driver naturally assumes that the speed is constant. The fact is that if the car is cornering, or going down or climbing up a hill, it is accelerating despite the constant speed shown on the speedometer. In the following section, we establish the concepts of displace-ment, velocity and acceleration. In particular, we clarify the distinction between speed and velocity, often used as synonyms by non-mathematicians, and the cause of the apparent contradiction of the accelerating car with its constant speedometer reading. 1.2 Definition of kinematic quantities Now we present formal definitions of displacement, distance, velocity, speed and acceleration which should help us to make a start in clearing up miscon-ceptions. Consider the fixed points P and Q , illustrated in Figure 1.1. The displacement from P to Q represented by the vector PQ ! s is the translation that is needed to move the point P to the point Q .
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