Internal sensors

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Internal sensors
Josep Amat and Alícia Casals Automatic
Control and Computer Engineering Department
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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 Cha
pter 7. Robotics applications. Robotization
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Chapter 2. Robot Morphology

• 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.

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User
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Mechanical
Internal sensors
Actuators
Mechanical structure
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Optical From the interruption of a light beam,
or reflection.
Internal sensors
Actuators
Mechanical structure
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Types of sensors
Angular
Linear
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Types of sensors
Resistive (Potentiometers) Angular

Analog
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Types of sensors
Resistive (Potenciometers) Angular
Inductive ( Resolver )

Analog
Digital
A is obtained through the lecture in a look up
table of arcsin and arccos
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e
A
S1
S2
Ve V sin (wt)
S1 V sin(wt ) cos a
S2 V sin(wt ) sin a
Possibility of obtaining the value of a by means
of tracking
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Types of sensors
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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
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Example of a disc with the Gray code
Example of an angular encoder
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Types of Sensors
Resistive (Potentiometers) Angular
Inductive ( Resolver )
Absolute Incremental
Analog
Digital
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Commercially 10 bits ?1024 div. ? Resol.
0.35º 12 bits ?4096 div. ? Resol. 0.088º 14 bits
?16384 div. ? Resol. 0.022º
Signal obtained after displacing the sensor over
a coded disc
1 2 3 4 5 6 7 8 9 10 11
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Gray code
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Commercially 10 bits ?1024 div. ? Resol.
0.35º 12 bits ?4096 div. ? Resol. 0.088º 14 bits
?16384 div. ? Resol. 0.022º
Gray code
Possibility of detecting the counting sense using
two sensors
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P
Q
Q
P
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Computing resolution


q 170,6
Using a a 10 bits encoder directly coupled to the
motor axis
7,3 mm.
js
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Measuring strategies
1 n
0 j
0
360º
Encoder
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Measuring strategies
1 n
0 j
Encoder
0 360º
0 360º

Encoder coupled to the arm with a transmission
ratio m x n
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Computing resolution
q 8 210

q 8192
0,15 mm.
Using a 10 bits encoder coupled with a
164 transmission ratio
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0 1 2 3
199 200
With a 10 bits A/D converter r r/1024
200 x 1024 204.800
0,006 mm.
Sinusoidal light obtained from Moore interference
r lt 0,01 mm.
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Sensing with a linear potentiometer
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Inductosyn sensor

• With two secondary sensors shifted 90º, the
  resolution is 0,2 / 28 lt 0.001 mm

With an analog interpolation using a 8 bits ADC
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Types of sensors
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LVDT

• LVDT Linear Voltage Differential Transformed)

Linear sensing displacements
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Linear sensing displacements
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Types of sensors
Resistive (Potentiometers) Angular
Inductive ( Resolver )
Incremental Absolute
Resistive Inductive (
Inductosyn ) Linear LVDT
Optical rule
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