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ME 3230 Kinematics & Mechatronics – An Introduction
R. Lindeke, Ph. D. Introduction
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ME 3230 Kinematics & Mechatronics
Front Piece Matter Website: Easiest way to get there is via Department Home Page– Faculty – Lindeke – Course ME3230 Syllabus: Meeting Rooms Course Schedule Course Grading Professional Issues Text Materials: Required Main Text: Kinematics, Dynamics and Design of Machinery, 2nd Ed. by K. Waldron & G. Kinzel Mechatronics, Electronic Control Systems in Mech & Electrical Engineering, 3rd Ed. By W. Bolton Other Readings will be available on electronic reserve at UMD Library, see syllabus ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Lets Plant our Feet! The design of Mechanisms (and machines) is the key way that Engineers separate themselves from Scientists! Science is the study of what is; Engineering is the creation of what is TO BE! Waldron and Kinzel So then? Are you ready for the challenge … ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Some Definitions: Kinematics: Kinematics is the study of motion, quite apart from the forces which produce that motion. More specifically [it] is the study of position, displacement, rotation, speed, velocity, and acceleration. John Uicker, ME Professor at UWisc Kinematics is a subset of “Solid Mechanics” which deals with the study of relative motion. Art Erdman, ME Professor at UMTC Kinematics is the study of position and its time derivatives. Specifically, [it is] concerned with positions, velocities, and accelerations of points and with angular positions, angular velocities, and angular accelerations of solid bodies. It is the study of the GEOMETRY of MOTION. K. Waldren, ME Professor at Stanford University ME 3230 Kinematics & Mechatronics 11/8/2018
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Definitions Continued
Mechanism: A mechanism is a mechanical device that has the purpose of transferring motion and/or force from a source to an output Erdman A mechanism is a machine composed of rigid members that are jointed together. Waldron An assemblage of resistant bodies, connected by moveable joints, to form a closed kinematic chain with one link fixed and having the purpose of transforming motion F. Reuleaux, “The Father of Modern Kinematics” – a German Kinematician whose work marked the beginning of a systematic treatment of kinematics during the 1850’s ME 3230 Kinematics & Mechatronics 11/8/2018
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Mechanisms Can Be designed to serve 3 different tasks
These Tasks are as a: Path Generator where the designer is interested in the path taken by a “Tracer Point” Function Generator where the relative motion (or forces) of linkage’s (generally focusing) on the links connected to ground are of interest Motion Generator with the entire motion of the “coupler” portion of the linkage is of interest ME 3230 Kinematics & Mechatronics 11/8/2018
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Specific Linkage Tasks:
Extracted from: L.E. Torfason, “A Thesaurus of Mechanisms” in Mechanical Designer’s Notebooks, V. 5 Mechanisms, McGraw Hill, 1990. Snap Action Mechanisms Linear Actuators: stationarl screws w/ traveling nuts; stationary nuts w/ traveling screws; Single- and double-acting pneumatic or hydraulic cylinders Clamping Mechanisms Locational devices Rachets and Escapements Swinging or rocking mechanisms (Oscillators) ME 3230 Kinematics & Mechatronics 11/8/2018
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Specific Linkage Tasks:
Reciprocating Mechanisms (Scotch Yoke & Quick-return mechanisms) Reversing Mechanisms Couplings & Connectors – for transmitting power between shafts Sliding connectors Stop, Pause, and Hesitation Mechanisms – thinking CAMS (but also linkages!) Curve Generators – following a coupler curve Straight Line Generators (see images over) ME 3230 Kinematics & Mechatronics 11/8/2018
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Straight Line Generator Linkages
From: Uicker, et al, The Theory of Machines and Mechanisms, 3rd ed., Oxford Press, 2003. ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Definitions, cont. Joints: The coupling parts of a mechanism that allow relative motion in some direction(s) while limiting motion in other directions Lower Pair joints: Contact between joined links occurs at every point of a surface segment Higher Pair joints: Contact between joined links occurs at isolated points or along line segments (implies much high contact forces) ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Lower Pair Joints: ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Higher Pair Joints ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Definitions, cont. Degrees of Freedom -- Connectivity A representation of the type of motion permitted by a joint Number of Degrees of freedom (of a joint or ultimately a mechanism) is equal to the number of independent coordinates needed to uniquely specify the location (position and orientation) of one link to the other in a pair connected by a joint In Planer Motion, the max number of DOF is ??? In 3-D Motion this number is: ??? ME 3230 Kinematics & Mechatronics 11/8/2018
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Planer Kinematic Linkages
A Planer linkage is one in which all points velocities are directly parallel to the “Plane of Motion” Axes of rotation of joints are normal to this plane Revolute joints are represented by points or small circles Direction of sliding of all prismatic joints are parallel to this plane ME 3230 Kinematics & Mechatronics 11/8/2018
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Representing Linkages
Binary Jointed Link Ternary Jointed Link Quaternary Jointed Link ME 3230 Kinematics & Mechatronics 11/8/2018
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Conventional Representation of Planer Linkages:
Ternary Link Binary Link Quaternary Link ME 3230 Kinematics & Mechatronics 11/8/2018
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Representation of Linkages With Prismatic Joints
4-Bar (a) and 6-Bar (b) Representations ME 3230 Kinematics & Mechatronics 11/8/2018
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Linkages of Special Interest
The most fundamental linkage is the 4-bar It consists of 3 moving links and 1 fixed link The Links are: Ground/Base link (fixed) Input Link (“driver” mover and connected to ground) Output Link (“driven” mover and connected to ground) Coupler or Floating Link (moving and connects driver to driven link) 6-Bar Linkages – are extensions of these simple one and are also found extensively ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
A 4-bar Example: Here we see a model of the Physical Linkage – And a ‘Linkage Chain’ or ‘Frame Skelton’ ME 3230 Kinematics & Mechatronics 11/8/2018
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Slider – Crank Mechanism
It is a special Case 4-bar linkage with one “infinitely long” prismatic link One of The MOST Common mechanisms of all! Why? ME 3230 Kinematics & Mechatronics 11/8/2018
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An Image: Input-Output could be reversed as in the IC Engine!
ME 3230 Kinematics & Mechatronics 11/8/2018
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Analytical Representation are most important!
Think about converting from a physical device to a reasonable motion equivalent This is sometimes called the kinematic skeleton or chain (as earlier) Consider mechanisms as a series of Joints that form a closed (or sometimes open) chain from ground to ground Standard 4-bar is: RRRR linkage Slider Crank is: RRRP linkage ME 3230 Kinematics & Mechatronics 11/8/2018
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For Example: A Tilt Window Mechanism from Erdman & Sandor’s Text
ME 3230 Kinematics & Mechatronics 11/8/2018
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ME 3230 Kinematics & Mechatronics
Makes this Skeleton: ME 3230 Kinematics & Mechatronics 11/8/2018
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