# Chapter 1- part 2 Introduction to Robotics. Robot Application 1.Machine loading 2.Pick and place operations 3.Welding 4.Painting 5.Sampling 6.Assembly.

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Chapter 1- part 2 Introduction to Robotics

Robot Application 1.Machine loading 2.Pick and place operations 3.Welding 4.Painting 5.Sampling 6.Assembly operation 7.Manufacturing 8.Surveillance 9.Medical applications 10.Assisting disabled individuals 11.Hazardous environments 12.Underwater, space, and remote locations Briefly explain the role of Robotics in Industries. Dec 2010

A Staubli robot loading and unloading Staubli robot placing dishwasher tubs An AM120 Fanuc robot A P200 Fanuc painting automobile bodies Robot Application

Staubli RX FRAMS robot in a BMW A Fanuc LR Mate 200i robot removal operation The Arm, a 6 DOF bilateral force-feedback manipulator Medical Robot of German Robot Application

Robot Specification/ Characteristics: 1.No. of Axis 2.Degree of Freedom (DOF) 3.Tool Orientation (YPR) 4.Reach and Stroke 5.Repeatability, Precision & Accuracy 6.Loading capacity/Speed 7.Working Environment Define Reach & Stroke, Degree of Freedom and Accuracy. Dec 2011, June 2013

Translation & Rotation Movements

1. No. of Axis- An imaginary straight line along which all the links will rotate or translate. –Each Robotic manipulator has number of axis about which its link rotate or along which its link translate. –Number of Axes  Major axes, (1-3) => Position the wrist  Minor axes, (4-6) => Orient the tool  Redundant, (7-n) => reaching around obstacles, avoiding undesirable configuration

2. Tool Orientation (YPR) While the 3 major axis of the robot determines the shape of work envelope, the remaining 3 axis determine the kind of orientation that the tool or hand can resume. If 3 independent minor axis is available then arbitrary orientation in 3 D Workspace can be obtained. OperationDescriptionAxis 1Yaw (Left Right) F 1 - Rotation about 1st axis 2Pitch (Up Down)F 2- Rotation about 2nd axis 3Roll (Rotate)F 3 - Rotation about 3rd axis

Tool Orientation Examples

3. Degree of Freedom (DOF)- The no. of independent movements a robot can perform in a 3-D Space. Direction in which a robot moves when a particular joint is activated. Basic motion configurations utilizes 3 DOF in the arm. 3 DOF located in the wrist give the end effector all the flexibility. A total of 6 DOF is needed to locate a robot’s hand at any point in its work space. Although 6 DOF are needed for maximum flexibility, minimum DOF for any robot should be 4 i.e. 3 for positioning and 1 for orientation. The more the DOF, the greater is the complexity of motions encountered.

DEGREES OF FREEDOM (CONTD.) The Three Degrees Of Freedom Located In The Arm Of A Robotic System Are: 1.The Rotational Reverse: Is The Movement Of The Arm Assembly About A Rotary Axis, Such As Left-and-right Swivel Of The Robot’s Arm About A Base. 2.The Radial Traverse: Is The Extension And Retraction Of The Arm Or The In-and-out Motion Relative To The Base. 3.The Vertical Traverse: Provides The Up-and-down Motion Of The Arm Of The Robotic System. The Three Degrees Of Freedom Located In The Wrist, Which Bear The Names Of Aeronautical Terms, Are 1.Pitch Or Bend: Is The Up-and-down Movement Of The Wrist. 2.Yaw: Is The Right-and-left Movement Of The Wrist. 3.Roll Or Swivel: Is The Rotation Of The Hand.

4. Reach and Stroke 1.Horizontal Reach (H.R)- It is defined as maximum radial distance the wrist mounting flange can be positioned from the vertical axis about which the robot rotates is called H.R. 2.Vertical Reach (V.R)- Maximum elevation above the work surface the wrist mounting flange can reach is called V.R. 3.Horizontal Stroke (H.S)- The total radial distance that the wrist can travel is called H.S. 4.Vertical Stroke (V.S)- Total vertical distance that the wrist can travel is called V.S.

Reach & Stroke Note:- Outer Radius= Horizontal Reach Inner Radius=Horizontal Reach- Horizontal Stroke Height=Vertical Stroke

Problem on Reach & Stroke 1.Suppose a cylindrical Co-ordinate robot has a vertical reach 480 mm and a vertical stroke of 300 mm. How far off the floor do parts have to be raised in order to be reachable by the robot?  Since robot cannot move below 300 mm so floor parts have to be raised by 180 mm. = 480-300 mm = 180 mm In order that the parts are reachable by the robot.

5. Repeatability, Precision & Accuracy 1. Repeatability: It is defined as measure of the ability of the robot to position the tool tip in the same place repeatedly. OR Repeatability: Ability of the robot to do the same job again & again repeatedly and then to come back again to its original position. –Repeatability is measured in mm. Repeatability Errors: –Due to slip in gears –Due to continuous operation there is wear and tear in mechanical parts.

5. Repeatability, Precision & Accuracy 2. Precision (Spatial Resolution): Measure of the spatial resolution with which the tool can be positioned within the work envelope. OR Precision: The Smallest distance the tool tip can be moved in the workspace of the robot. Example: –If the tool tip P is positioned at point A and the next closest position that it can be moved to is the point B then the precision along that direction is the distance between point A and Point B.

5. Repeatability, Precision & Accuracy 3. Accuracy: It is ability of robot to place the tool tip at the prescribed point. Example: –If the user commands the robot to move to the position (1,2,3) and if the robot goes to the exact prescribed position then accuracy is 100 %. –If the robot is commanded to move to 2cm/30 degree and if it moves exactly then it is accurate. But if it moves 1.9cm/2.1 cm and 29/31 degree then it is said to be fairly accurate. Note: –The robot will have better accuracy only if he have better resolution or precision. –Low Accuracy, High Repeatability –High Accuracy, Low Repeatability Accuracy directly proportional to Precision Accuracy inversely proportional to Repeatability.

Compare Precision, Accuracy & Repeatability for different Robots Type of Robot Vertical Precision Horizontal Precision RepeatabilityAccuracy RectangularUniform Very Good + Highly Accurate CylindricalUniform Decreasing radially Good + Accurate Spherical Decreasing radially Satisfactory Less Accurate SCARAUniform Decreasing radially Very Good Articulate Decreasing radially GoodVery, Very Less Accurate

University Asked Questions Define Precision, Accuracy & Repeatability. For Which type of robot is overall precision uniform and for which type of robots vertical precision uniform? Dec 2010 Briefly explain the role of Robotics in Industries. Dec 2010

6. Loading Capacity / Speed  Speed and acceleration –Faster speed often reduces resolution or increases cost –Varies depending on position, load. –Speed can be limited by the task the robot performs (welding, cutting)

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