Motors and Drivers


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Motors and Drivers

  1. 1. Motors and DriversThinkLABS
  2. 2. Actuators: The Family Actuators Rotational Linear DC Motors Stepper Motors Pneumatics Artificial MusclesGeared RC Servo Unipolar Bipolar
  3. 3. DC Motor Backbone of major actuators in robotics Available in various shapes, sizes and ratings Easy to use
  4. 4. Geared Motors A DC motor with a gear head on its output shaft Principle of gear reduction used Amplifies torque and reduces speed Absolutely necessary Available in wide range of gear reduction ratios [ My summer dream collection ;-) ]
  5. 5. Inside a Geared Motor
  6. 6. The Right Geared Motor How to select the right motor for your robot? Its all about Speed & Torque For small robots, speeds of 60 – 150rpm is ideal and torque in the range of 2Kgcm Gear reduction ratio can approximate torque All depends on the DC motor used, bigger, meaner, the better
  7. 7. Motor Drivers Motor Motor Logic block Driver Motor Power Supply Basic Block Diagram of a Motor Controller
  8. 8. Motor Drivers: Types Drivers Electromechanical Solid-State Relays BJTs & (SPST,SPDT,DPST,DPDT) MOSFETs
  9. 9. RELAYS V/S BJTS Relays BJTs (Solid State) • Has a high power • Power rating is rating. smaller than relays. • High power • Very small power consumption. consumption. • Slower in response. • Fast response. • May produce noise • Immune to noise. at the output. • Size?? • Size??
  10. 10. Relays V/S BJTs
  11. 11. Motor Drivers: Solid State Drivers built using Transistors Fast, Efficient and Small Also available in Integrated Packages Ideal for our needs !!
  12. 12. Motor Drivers: Solid SateBasic Motor Driver (ON/OFF) using a BJT
  13. 13. Motor Drivers: Solid SateProblems with this Circuit?
  14. 14. Motor Drivers: Solid SateBasic Motor Driver (ON/OFF) using a BJT
  15. 15. Motor Drivers : Bi-DirectionalBut how about changing the motor direction as well??
  16. 16. Motor Drivers : H-BridgeH Bridge / Full Bridge H Bridge is capable of driving a DC motor in both the directions. Based on the switch states, direction of the motor can be changed.
  17. 17. H-Bridge Case 1Case 1: When switch S2 and S3 are closed, current will flow from right to left of the motor. Now, the motor will rotate in one direction, say Clockwise.
  18. 18. H-Bridge Case 2Case 2: When switch S1 and S4 are closed, current will flow from left to right of the motor. Now, the motor will rotate in another direction, ie., Counter Clockwise.
  19. 19. H Bridge Design 1
  20. 20. H Bridge Design 2
  21. 21. H-Bridge using BJTs
  22. 22. H-Bridge using BJTs : Case 1 A B T1 T2 T3 T4 0 1 ON OFF OFF ON
  23. 23. H-Bridge using BJTs : Case 2 A B T1 T2 T3 T4 1 0 OFF ON ON OFF
  24. 24. H Bridge Design (Buffered)
  25. 25. Complete H Bridge
  26. 26. H Bridges: Integrated Circuits Darlington pairs available in IC packages : ULN XX H Bridges available in IC packages : L298, L293D, LMD1800 and many more…
  27. 27. Driving Motors
  28. 28. ANY QUESTIONS?