Medical Robotics Applications & Design Considerations (Part 1) Dr. James Smith

Transcription

1 Medical Robotics Applications & Design Considerations (Part 1) Dr. James Smith

2 A Short History of Robotics

3 Abu Al-Jazari ( ) Arabic scholar during the Islamic Golden Age. Invented the crank-shaft and connecting rod Invented an escapement mechanism and cogged gears allowing machines to be programmed Called the Father of Modern Engineering and the Father of Robotics A hydropowered water-raising machine A valve-operated reciprocating suction piston pump The elephant clock Programmable humanoid robots.

4 Leonardo Da Vinci ( ) Was an artist and military during the Italian Renaissance. Designed and built programmable automata. After his death his works were destroyed and sketches scattered and was forgotten about as an engineer until the 1800 s Built a programmable robotic knight to entertain visitors to a castle. Built a programmable cart which carried a robotic lion that entertained guests at a party.

5 Nikola Tesla ( ) Serbian who emigrated to the U.S. at 28 Invented AC electricity generation, AC transmission, AC motors, and radio. The man who invented the twentieth century Many people credited Marconi and Edison with many of Tesla s inventions (because he was not American) but the U.S. Supreme Court eventually sided with Tesla on all patent disputes He demonstrated robotic radio-controlled boats in 1898 at Madison Square Garden

6 Alan Turing ( ) Englishman known as the father of computer science Invented the idea of a programmable computer (Universal Turing Machine) in 1936 Built machines to break the German enigma code in WWII Proposed the Turing Test to establish whether a machine is intelligent or not in 1950 A turing machine made with Lego Mindstorms RCX

7 Famous Robots Unimate Puma 560 Widely used manipulator irobot s Roomba Most successful home vacuum robot Marc Raibert s Hoppers First successful running MIT & CMU

8 Robot Manipulators

9 Electromechanical Arms Mech. Linkages Motors Electrical Pneumatic Hydraulic Sensors Angle Vision Force Etc.

10 Mechanical Linkages: Kinematic chains Know lengths Track angles Need linear algebra & matrices! MTH 141 PCS 211 Kinematics

11 Electrical Common Clean Compact Pneumatic Fast Light Compressor needed Hydraulic Powerful Dirty Pump needed Actuation Types

12 Angle Potentiometers Incremental Encoders Velocity Tachometer Derivative of Angle Force Accelerometers Strain Gauges Sensors

13 Sensors Ultrasound Motion (Doppler) Range (ToF) Vision Visible Invisible Electromagnetics EMG EKG 3D Visual Target Tracking

14 Important Concepts Physical concepts Hooke s Law Newton s Second Law Motor and Load interaction

15 Hooke s Law Force in a spring (F) Proportional to change in length (!l) Spring constant: k F = k " #l

16 Applying Hooke s Law Force Control: Sensing Motor Load Don t apply voltage to motor Apply an unknown mass to the motor Resulting displacement corresponds to load on motor by the mass. What is a good spring location? Mass Motor

17 Motor Voltage & Speed Lego motors accept voltage commands via software The motor speed varies with applied voltage Higher voltage batteries also speed up the motors When motor is loaded you need to apply a larger voltage to get enough current.

18 Force Control: Generate a Known Force Motors produce forces (torques) Attach a linear spring to the motor shaft Send a voltage command to motor Motor shaft angle corresponds to the spring force

19 Haptic Rendering Algorithm Collision detection & response Position & Orientation Force & Torque Contact Info Collision Detection Collision Response Object Database (Geometry & Material)

20 Design Considerations for Robots in Medicine

21 System Selection Function Safety User Interface Cost

22 Categories Manipulation type Teleoperation Autonomous Control Mode Admittance Measure force & produce displacement Impedance Measure displacement & produce force

23 Robots in Surgery Puma 560 Needle in brain biopsy Robodoc Milling in femur for hip replacement da Vinci Surgical System Laparoscopic procedures Cardiac valve repair & others

24 Da Vinci Robot Teleoperation Non-autonomous $ in consumable parts per operation Very expensive

25 Surgical Robotics in Action

26 Surgical Robots in Action

27 Haptics: Enhancing Surgical Robots Relating to sense of touch As opposed to optic (sight) Why? Simulation Human performance studies

28 How can YOU explore medical robotics? It s within reach!

29 Medical Robot Development Process Identification of pathology or ablation What needs fixing? Identification of affordable technology What motors and sensors? At what cost? Determine level of functional replacement What is possible? Keep it simple & effective! Risk evaluation Never underestimate what can go wrong! Failures always occur. What is the acceptable risk level? Prototype device, test & start again Test on larger population set International certification Manufacture & distribute device Long process: up to 15 years! Otto-Bock C-leg development began in the 1980s; released in 1999 Start Prototype Test Manufacture End

30 Commercial Toolkits Commercial Off-the-Shelf Cheap ($300 - $700) Easy to obtain Refined user interfaces Examples Lego Mindstorms Vex Fischer Technik

31 LEGO Mindstorms NXT From: Lego Mindstorms NXT Components by paytonrwhite Manipulating Everyday Objects with Prosthetic Hands 31

32 NXT BRICK 32-bit ARM Processor KB Flash - 64 KB RAM 4 button user interface 100 x 64 LCD Display Speaker A/B/C Output Ports Motors 1/2/3/4 Input Ports Sensors USB download interface Manipulating Everyday Objects with Prosthetic Hands 32

33 NXT Programming: Option 1 NXT-G Visual / GUI programming Comes with Lego Mindstorms Integrated debugging & downloading USB & Bluetooth

34 NXT Programming: Option 2 C-like progamming language Harder, but more powerful & flexible than NXT-G Use Bricx interface in Windows or Text Editor in Unix Use Not exactly C compiler NXT Brick executes resulting Byte Code (NBC) Download programs using USB - linxt (Linux) or BricxCC (Windows) Manipulating Everyday Objects with Prosthetic Hands 34

35 NXT Buttons Centre Button (square) On/Enter/Run Arrow Buttons left/right select Rectangular Button Clear/Go Back/ exit Manipulating Everyday Objects with Prosthetic Hands 35

36 Not exactly C Program: btn.nxc // NXC LCD Button Demo // Task main() { Int count = 0; TextOut(0,LCD_LINE1, LCD > ButtonDemo ); while(count < 5) { count = ButtonCount(BTNRIGHT,false); NumOut(0,LCD_LINE2,count); } } Manipulating Everyday Objects with Prosthetic Hands 36

37 Compile Upload Run File NXCdefs.h must be in the directory Compile: Upload: Run: nbc I=. btn.nxc -O=btn.rxe linxt u btn.rxe My Files/Software Files/btn Manipulating Everyday Objects with Prosthetic Hands 37

38 NXT Sensors Ultrasonic Sensor - detect objects - measure distance to object Touch Sensor - touch / no touch (on/off) Light Sensor - distinguish light/dark - measure light intensity Sound Sensor - ~3 6 KHz - measure sound level (db/dba) Manipulating Everyday Objects with Prosthetic Hands 38

39 NXT Servo Motor Connect to Outputs A/B/C Built-in rotation sensor - Measure angle - Measure # of rotations - Motor may be off Continuous rotation - Fwd/Rev Power/Speed Rotate (Servo Mode) - Fwd/Rev # of degrees - PID control Manipulating Everyday Objects with Prosthetic Hands 39

40 NXT View Test Sensors Sensors connect to inputs 1/2/3/4 NXT program View used to test sensors Select View / Sensor Type / Run - Use to verify sensor operation - Display sensor measurement value Motors connect to outputs A/B/C Motors include a rotation sensor - Display motor rotation angle - Display # of rotations Manipulating Everyday Objects with Prosthetic Hands 40

41 NXC Documentation / Examples Next Byte Codes & Not exactly C NXC documentation Programmers guide NXC Examples see: nxcsamples.zip Manipulating Everyday Objects with Prosthetic Hands 41

42 Robotics Competition