1. Internal sensors Josep Amat and Alícia Casals Automatic Control and Computer Engineering Department

2. Program Chapter 1. Introduction Chapter 2. Robot Morphology Chapter 3. Control Chapter 4. Robot programming Chapter 5. Perception Chapter 6. Mobile robots. Architecture, components and characteristics Chapter 7. Robotics applications. Robotization

3. 2.1 – Mechanical Structures. Classical Architectures. 2.2 – Characteristics of a Manipulator. Definitions. 2.3 - Actuators. Pneumatic, Hydraulic and Electrical. 2.4 – Movement transmission systems: Gearboxes, movement transmission and conversion. 2.5 – Robot internal sensors. Position sensors, speed and acceleration. 2.6 – End Effectors. Chapter 2. Robot Morphology

4. User Components of a Robot Control Unit Programming External Sensors Environment Internal Sensors Actuators Mechanical Structure Net

5. Internal sensors Actuators Mechanical structure Detectors Position sensors Mechanical:

6. Internal sensors Actuators Mechanical structure Detectors Position sensors Electromagnetic: Detection from the variations of the oscillation conditions of an L – C sensor circuit

7. Internal sensors Actuators Mechanical structure Detectors Position sensors Optical: From the interruption of a light beam, or reflection.

8. Types of sensors Angular Linear

9. Resistive (Potentiometers) Angular Analog Digital R1 R2 Vcc 0 V R  V = Vcc R1 R  R V = Vcc   R   = Vcc Types of sensors

10. Resistive (Potenciometers) Angular Inductive ( Resolver ) Analog Digital V e = A sin (  t) V e = A sin(  t ) cos  V e = A sin(  t ) sin  A is obtained through the lecture in a look up table of arcsin and arccos Types of sensors

11. V e = V sin (  t) S 1 = V sin(  t ) cos  S 2 = V sin(  t ) sin  A S1S1 S2S2 S 1 = V cos  S 2 = V sin  e Possibility of obtaining the value of  by means of “tracking” A/D D/A  controler   Low resolution conversions High resolution conversions XX XX

12. Resistive (Potentiometers) Angular Inductive ( Resolver ) Absolute Incremental Analog Digital Types of sensors

13. Optical Encoder Absolute 2 paths 4 divisions Fotoelectric sensor n paths 2 n divisions n optical barriers

14. Commercially 10 bits  1024 div.  Resol. 0.35º 12 bits  4096 div.  Resol. 0.088º 14 bits  16384 div.  Resol. 0.022º Encoder diameters: de 50 a 175 mm Elimination of the reading ambiguity using the Gray code Ambiguity when reading the natural binary code

15. Example of a disc with the Gray code Example of an angular encoder

16. Resistive (Potentiometers) Angular Inductive ( Resolver ) Absolute Incremental Types of Sensors Analog Digital

17. Gray code Commercially 10 bits  1024 div.  Resol. 0.35º 12 bits  4096 div.  Resol. 0.088º 14 bits  16384 div.  Resol. 0.022º 1 2 3 4 5 6 7 8 9 10 11 12 Signal obtained after displacing the sensor over a coded disc

18. Gray code Commercially 10 bits  1024 div.  Resol. 0.35º 12 bits  4096 div.  Resol. 0.088º 14 bits  16384 div.  Resol. 0.022º Possibility of detecting the counting sense using two sensors

19. Incremental Optical Encoder ABRABR 1 mark = 4 divisions

20. 0 1 200 x 4 = 800 P Q P Q

22. ss 120 cm. Computing resolution  = 60º l = 2  1200 60 360 q = 2 10 60 360 l = 1256 mm. = q = 170,6 = r r = 1256 mm. 170,6 = 7,3 mm. U sing a a 10 bits encoder directly coupled to the motor axis

23. 1 : 1 Measuring strategies Arm 0 360º 0  Encoder Absolute Incremental d n-1.... d o Counter d n-1.... d o Code 

24. 1 : n Measuring strategies Arm 0 360º 0  Encoder Absolute Incremental d n-1.... d o Counter d n-1.... d o Code  n = 360º 

25. 1 : n Measuring strategies Arm 0 360º 0  Encoder n = m 360º  0 360º m · · · m = 2 m = 1 Absolute + Inc. Incremental d n+p-1.. d n-1 · · · · d o Code  Counter d n+p-1.. d n-1 · · · ·d o Encoder coupled to the arm with a transmission ratio: m x n

26. 120 cm. Computing resolution  = 60º l = 1256 mm. q = 8192 = r r = 1256 mm. 8192 = 0,15 mm. q = 8 · 2 10 x 6 x 8 Using a 10 bits encoder coupled with a 1:64 transmission ratio

27. l = 1256 mm. 200 x 1024 = 204.800 r = 1256 mm. 204.800 = 0,006 mm. r < 0,01 mm. Sinusoidal light obtained from Moore interference With a 10 bits A/D converter r’ = r/1024 0 1 2 3 · · · 199 200

28. Types of sensors Resistive (Potentiometers) Angular Inductive ( Resolver ) Incremental Absolute Resistive Inductive ( Inductosyn ) Linear LVDT Optical rule Analog Digital Analog Digital

29. R Sensing with a linear potentiometer

30. Types of sensors Resistive (Potentiometers) Angular Inductive ( Resolver ) Incremental Absolute Resistive Inductive ( Inductosyn ) Linear LVDT Optical rule Analog Digital Analog Digital R

31. Inductosyn sensor With two secondary sensors shifted 90º, the resolution is: 0,2 / 2 8 < 0.001 mm * 0,2 mm * With an analog interpolation using a 8 bits ADC

32. Types of sensors Resistive (Potentiometers) Angular Inductive ( Resolver ) Incremental Absolute Resistive Inductive ( Inductosyn ) Linear LVDT Optical rule Analog Digital Analog Digital

33. LVDT = Linear Voltage Differential Transformed) LVDT Linear sensing displacements

34. V1V1 V2V2 V 1 - V 2 V1V1 V2V2 v LVDT Linear sensing displacements

35. Types of sensors Resistive (Potentiometers) Angular Inductive ( Resolver ) Incremental Absolute Resistive Inductive ( Inductosyn ) Linear LVDT Optical rule Analog Digital Analog Digital

36. Head reader Incremental optical rule Absolute optical rule