1. Harpeth Hall Winterim 2016 Servo Motors, Stepper Motors, and DC motors ARMA Lab Vanderbilt University Prepared by Rashid Yasin Harpeth Hall Winterim January 2016

2. Harpeth Hall Winterim 2016 Overview Robots need to move Many different kinds of actuators Today, we will review servos, DC motors, stepper motors http://2.bp.blogspot.com/- yhKSTGwrIX4/UfrLm60CnOI/AAAAAAAAA DM/NY5BMn1oOp0/s1600/stepper_motor.j pg https://electrosome.com/wp- content/uploads/2012/06/Servo-Motor.gif http://image.made-in- china.com/4f0j00qvUamTtdbgoF/DC-Motor-RF-385-.jpg

3. Harpeth Hall Winterim 2016 What is a servo motor? 2 words servo, motor  Servo (servomechanism)  Motor Generally refers to comparatively low-cost motors that are used for precise positioning tasks Often used in RC hobbyist builds or in prototyping  Not limited to such uses http://www.hizook.com/files/users/3/Trossen_Giger_Robot.jpg

4. Harpeth Hall Winterim 2016 What to use servo motors for Need accurate position control Don’t need rotation more than 180 or 260 degrees

5. Harpeth Hall Winterim 2016 Servo Motor Components Motor Gear train Feedback sensor (potentiometer)

6. Harpeth Hall Winterim 2016 Servo Motor Components - Motor

7. Harpeth Hall Winterim 2016 Servo Motor Components – Gear train

8. Harpeth Hall Winterim 2016 Servo Motor Components - Sensor

9. Harpeth Hall Winterim 2016 Connecting a servo motor 3 cables Power, ground, signal Power almost always the same – some constant voltage

10. Harpeth Hall Winterim 2016 Servos http://www.robotplatform.com/knowledge/servo/servo_tutorial.html Servos are pulse length modulation controlled  Which, dumbly, isn’t a real thing. Sigh

11. Harpeth Hall Winterim 2016 Servo Motor Signal Digital signal: high or low Time-dependent Runs on a clock – every 20 ms!???? (200 hz????) If the motor does not get a signal, it will turn off  Location

12. Harpeth Hall Winterim 2016 Controlling a servo with Arduino

13. Harpeth Hall Winterim 2016 Controlling a servo with Arduino and a pot

14. Harpeth Hall Winterim 2016 “Closed loop” control Servo is an example of “closed loop” control Often better to Examples:  Toaster, dryer, sprinkler  Stepper motors: used in printer heads  Continuous servos

15. Harpeth Hall Winterim 2016 Continuous Servos Similar to a DC motor, but based around a servo Allows for multi-turn applications https://www.pololu.com/blog/24/continuous-rotation-servos-and-multi-turn- servos

16. Harpeth Hall Winterim 2016 Steppers http://homepage.cs.uiowa.edu/~jones/step/

17. Harpeth Hall Winterim 2016 DC Motors

18. Harpeth Hall Winterim 2016 Transistors Act like an amplifier

19. Harpeth Hall Winterim 2016 Transistor Data sheet In your Arduino kit, you have a transistor https://www.sparkfun.com/datasheets/Components/2N3904.pdf I

20. Harpeth Hall Winterim 2016 Controlling a DC motor with arduino

21. Harpeth Hall Winterim 2016 Mechanisms There is a lot you can do with only rotary joints Many robot manipulators only have rotary joints in an “open chain” We can intelligently use links, joints, and actuators to make different motion profiles Examples:

22. Harpeth Hall Winterim 2016

23. Moving from rotary to linear motion Can use mechanisms to get linear motion

24. Harpeth Hall Winterim 2016 Linear actuators But sometimes, we need more than just a mechanism, need a different kind of actuator Lead screw – many kinds, very common Solenoid Voice coil Pneumatic/hydraulic