Mechanical Electrical Digital

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1 Mechatronics I: Mechanical Systems Richard Voyles Week 1 Based on notes from Paul Rullkoetter Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element Mechanical Electrical Digital 2 1

2 Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element Actuat a device that transfms electrical energy ( some other fm) to kinetic energy; e.g. electric mot hydraulic piston. 3 Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element Sens a device that produces a signal in proption to a quantity being measured. Transducer a device that converts (transfms) one physical quantity (e.g. luminance, sound, col, texture, pressure, voltage, current, etc.) into another. 4 2

3 Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element a device circuitry that transfms (converts) the electrical signals from one component to match the electrical signal characteristics to another component. conditioning entails: Isolation impedance matching Amplification Filtering (noise reduction) 5 Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element DAC (Digital to Analog Conversion) a device that converts the digital (binary) output from a computer to an electrical (analog) signal. 6 3

4 Mechatronic Systems Mechanical Structure Actuats Senss Transducers DAC ADC Computer Digital Processing Element ADC (Analog to Digital Converter) a device that converts electrical (analog) signals to a digital (binary) value. 7 Why Study Mechanisms? We might want to build: Vehicle steering mechanisms End effects, manipulats Multi-DOF robotic arms Walking robot locomotion Docking, refueling, box exchange mechanisms We might want to test: Dynamic fce analysis to spec required mots, servos, structural components Structural moniting of fuel tanks, cryo, fuselage 8 4

5 Objectives Understand basics of mechanism kinematic and kinetic analysis using planar linkages DOF 4-bar mechanism, Grashof condition Inversion, isomers; 4 bar inversions Kinematic analysis using VLE; including multi-loop, loop, multi-dof and rolling contact Kinematic coefficients, point path Graphical velocity analysis using instant centers; Kennedy s theem Dynamic fce analysis Newton-Euler equations Power equation Flywheel sizing Balancing Estimate stress/strain in links, estimate life 9 Basic Terminology 5

6 DOF Degrees of freedom? Number of independent parameters required to specify position 11 Links Moving parts termed links; must transmit fce with small defmation Assumed to be rigid bodies 12 6

7 Joints Kinematic Pairs 13 Kinematic Chain How many DOFs f each chain? 14 7

8 Mobility (DOF) Gruebler s mobility equation: M = 3(n-1) 2J 1 J 2 Where: n = # of links J 1 = 1 DOF joints J 2 = 2 DOF joints 4-bar: 3(4-1) 2(4) 0 = 1 15 Mobility Definitions >= 1 is a Mechanism 0 is a structure < 0 is a pre-loaded structure 16 8

9 Exceptions! 17 Mobility Examples 18 9

10 4 Bar Mechanism 1 DOF motion control Most common mechanism in machinery Very versatile in motion generated / motion control 19 4 Bar Inversions 20 10

11 4 Bar Inversions 21 Grashof Condition Determine if a 4 bar link can perfm full rotation S + L <= P + Q Where S = length of shtest link L = length of longest link P,Q = the other two! Class I chain Grashof (<) Class II chain non-grashof (>) Class III chain special equality case (=) Toggle change points when links become colinear and behavi indeterminate 22 11

12 4 Bar Inversions: Grashof 23 4 Bar Inversions: Non-Grashof 24 12

13 Special Case Grashof 25 Isomers 26 13

14 Toggle Positions Colinearity of the moving links Check f presence of toggle positions during synthesis Limited undetermined motion 27 Transmission Angle Simplified assessment of quality of fce transmission through 4 bar Angle between output link and the coupler ROT: keep above 40 deg minimum 28 14

15 29 15

ME 321 Kinematics and Dynamics of Machines

ME 321 Kinematics and Dynamics of Machines .0 INTRODUCTION ME Kinematics and Dynamics of Machines All Text References in these notes are for: Mechanism Design: Analysis and Synthesis, Volume, Fourth Edition, Erdman, Sandor and Kota, Prentice-Hall,