Handson Sessions on Learning Robot Kinematics using Robo

Hands-on Sessions on Learning Robot Kinematics using Robo. Analyzer* Prof. S. K. Saha Dept of Mech Engg IIT Delhi saha@mech. iitd. ac. in Mr. Rajeevlochana G. Chittawadigi Dept of Mech Engg Amrita School of Engineering, Bengaluru rg_chittawadigi@blr. amrita. edu *Developed at IIT Delhi

Contents • • Robotics Education Homogenous Transformation Denavit-Hartenberg Parameters Forward Kinematics Inverse Kinematics Motion Planning (Virtual Robot Module) 2

Robotics • Design, development, control and application – – – Industries Academics Research Entertainment Medical applications etc. • Included in curriculum of universities Source: Mechatronics Lab and PAR Lab, IIT Delhi 3

Robotics Education Courses* usually include: 1. Theory: – – Design and working of robot in the form of drawing and pictures Mathematically intensive 2. Practical: – – – CAD modeling and simulation Real robots in action Not many institutes have facilities *Mechanical Engineering Source: http: //images. google. com 4

Robotics Concepts • • Homogenous Transformations DH Parameters Kinematics Dynamics Motion Planning … Difficult to Visualize Robo. Analyzer Software: Priceless!! Free to use: http: //www. roboanalyzer. com 5

Robo. Analyzer • • 3 D Model Based Robotics Learning and Teaching Software Developed by Prof. S. K. Saha and Team (IIT Delhi) Main Developer: Mr. Rajeevlochana G. Chittawadigi Other Developers – – – – – Dr. Suril V Shah Mr. Ratan Sadanand Mr. Ravi Joshi Mr. Amit Jain Ms. Jyoti Bahuguna Mr. Sasanka Sekhar Sinha Mr. Sai Vikas Maram Mr. Yashaswi Kuruganti … 6

Robo. Analyzer Website: • http: //www. Robo. Analyzer. com • Download latest version (V 7. 5) from http: //www. roboanalyzer. com/downloads. html • After download, unzip it • Robo. Analyzer. exe 7

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Homogenous Transformation Matrix (HTM) Module • Top Panel Button of Robo. Analyzer Window • Translation – Local Frame – Global Frame • Rotation – Local Frame – Global Frame • Homogenous Transformation Matrix (HTM) 9

Task 1: Translation in HTM • Translate along X, Y and Z axes • Observe the last column (fourth) of the HTM • Translation alone is commutative 10

Task 2: Rotation in HTM • Rotate about X, Y and Z axes • Observe the first 3 x 3 matrix of the HTM – Direction Cosine – Projection of smaller axis vector on bigger frame – 3 columns => 3 vector projections • Rotation is not commutative 11

Task 3: Local v/s Global in HTM • Current transformation => Multiplication of individual HTMs • Local transformation => Post-Multiplication of HTMs • Global transformation => Pre-Multiplication of HTMs 12

Geometric Model of a Serial Robot • Robot – moves in Cartesian frame – controlled at joints • Mapping – Geometric model – Robot Architecture – Denavit-Hartenberg (DH) Parameters 13

Denavit-Hartenber (DH) Parameters • Line represented with respect to a coordinate frame • Common normal between Z and line • Generally used in Robotics

Denavit-Hartenber (DH) Parameters 1. Frame and Line 2. Z axis of Frame 3. Find Common Normal (Shortest Distance) between Z axis of Frame and Line

Denavit-Hartenber (DH) Parameters θ a b 1. Translate Z (b) till Intersection of Z axis and Common Normal Joint Offset 2. Rotate Z (θ) so that 3. Translate X (a) till 4. Rotate X (α) so that X axis aligns with Intersection of Common Z axis aligns with the Common Normal and Line Joint Angle Link Length Twist Angle α

Video on DH Parameters 17

Joint Axes 18

Joint Axes 19

Joint Axes 20

Joint Axes 21

DH Parameters • Geometrical description • 4 parameters α – Joint offset (b) – Joint angle (θ) – Link length (a) – Twist angle (α) α X 2 Z 3 2 θ 2 a 1 Z 1 Demo b 2 a 2 X 3 θ 1 1 b 1 Z 2 X 1 • Relates frames attached on consecutive links 22

Visualize DH Parameters A. 3 DOF and 3 R Robot B. Modify DH Parameters C. Visualize with Animation 23

Kinematics Study of motion of links without considering the forces θ 1 and θ 2 Forward Kinematics Joint Angles Demo Inverse Kinematics 24

Forward Kinematics T 2 • Joint to Cartesian space • End-effector configuration in base frame Demo T 3 [ ] Tee = T 1 T 2 T 3 = Q T 1 Px Py Pz 0 0 0 1 25

Task 4: Transformations • Robo. Analyzer Main Application • 2 R Robot (Spatial) • DH Parameters • Verify Transformation = • Try for Different Joint Angles 26

Task 5: Forward Kinematics • KUKA KR 5 Arc • FKin • Animation • Plots • Verify Position of EE Config • Try Different Motion 27

Task 6: Inverse Kinematics • • • Ikin Button MTAB Aristo Robot IKin: 8 Solutions Verify in RA Visualize in RA Try Different Robots 28

Dynamics Study of forces and moments causing the motion of links Forward Dynamics Inverse Dynamics Joint Accl. Joint Force Forward Dynamics Inverse Dynamics Demo Due to complexity, these are usually not taught in most of the UG courses 29

Virtual Robot Module • • Joint Jogging Cartesian Jogging 17 Robots Integration with MATLAB • Interface with Physical Teach Pendant Demo 30

Task 7: Virtual Robot Module • VRM_XML… • ABB IRB 1520 • Start Record Motion • Cartesian Control • Draw a Square of Side 100 mm • Stop Record Motion • Read and Playback 31

Contest: Virtual Robot Module • VRM_XML… • ABB IRB 1520 • Start Record Motion • Cartesian Control • Draw a Cube of Side 100 mm • Stop Record Motion • Read and Playback • Least Number of Motion Sequences!!! 32

Robo. Analyzer Team • • • • Subir K. Saha (1996 - present) S. Goel and S. Ramakrishnan (1996 -97) A. Patle (2000 -01) Rajat Jain (2009 -10) Suril V. Shah (2007 -11) Rajeevlochana G. Chittawadigi (2009 – 2013, 2015 -present) Amit Jain (2010 -11) Jyoti Bahuguna (2011 -12) Ratan Sadanand (2012 -15) Ravi Joshi (2014 -15) Keshav Bimbraw and Ishaan Mehta (2016 Summer) Sasanka Sekhar Sinha (2017 -present) Sai Vikas Maram and Yashaswi Kuruganti (2018 -19) www. roboanalyzer. com The feedback/suggestion of the below are sincerely acknowledged: • Mr. Arun Dayal Udai (2010): Suggested importing of CAD files in STL format • Dr. Sandipan Bandyopadhyay (2012): Suggested to make RA/VRM as an API/COM server to be integrated with other software • Prof. Sudipto Mukherjee (2012 -13): Suggested an interfacing with MATLAB • Dr. Nayan Kakoty (2013): Suggested to have custom trajectory file input for joints Prof. Peter Corke (2015): Discussion on integration of Robo. Analyzer (VRM) with Robotics Toolbox • Mr. Vinay Gupta (2016): Suggestion on having a link in the software for online feedback and contact form • Mr. Dharmender Jaitly, Dr. Majid Koul, Mr. Aamir Hayat, Mr. Riby Boby, many more 33

Complementary • Illustrations • Examples • Effective!!! 34

Feedback http: //www. roboanalyzer. com/feedback. html 35

Thank You • rg_chittawadigi@blr. amrita. edu • saha@mech. iitd. ac. in • roboanalyzer@gmail. com 36