丛书序
Preface
Chapter 1 Systems Study
1.1 Study of the Elements of the Functional Chains in the Industrial Environment
1.2 Technical Communication Tools
Chapter 2 Linear Continuous-Time Time-Invariant Systems
2.1 Modeling
2.2 Performance Evaluation of a Control System
2.3 Correction of Control Systems
Chapter 3 Chains of Rigid Solid Bodies
3.1 Kinematic Modeling
3.2 Classification of Mechanisms
3.3 Notion of Hyperstaticity
3.4 Modification of a Model
3.5 Modeling of Two-Dimensional Problems
3.6 Conclusions and Perspectives
Chapter 4 Dynamics and Energetics of Systems of Rigid Solid Bodies
4.1 Notion of Mass
4.2 Kinetics
4.3 Inertia
4.4 Dynamics
4.5 Energy
Chapter 5 GRAFCET Representation of Sequential Systems
5.1 Representation of Actions
5.2 Structuring of Grafcet Charts
5.3 Stability of the Grafcet Chart Model
5.4 Conclusion
內容試閱：
Cha,pter 1
Systems Study
1.1 Study of the Elements of the Functional Chains
in the Industrial Environment
1.1.1 Information Functional Chain
As seen in the first volume, the information functional chain is the set and
organization of the components which allow to acquire, process and transmit
the information.
Concept of Information Processing
The conversion of a physical data Dm temperature, velocity, etc. into a usable
data Ss which is most of the time electrical by a sensor is not sufficient, since
this latter signal Ss generally has a very low magnitude which is highly noised
by the disturbances endured by the sensor. The sensor hence is often associated
with the following components:
* a conditioner, which is an electronic circuit allowing the adaptation of
the signal Ss at the output of the sensor into a usable measure signal Sm,:
it often is a low-pass filter which attenuates the noise of the signal Ss, as
illustrated in Figure l.1. The signal Sm at the output of the conditioner
still has a low magnitude, but it is no longer noised. However, the signal
is delayed due to the low-pass filter.
* a transmitter, which allows to transmit the signal: its output signal St
may be the same as the signal Sm., but it is most often digitized since
the transmitter often is an Analog to Digital Converter ADC.
Figure l.1 principle of a low-pass filter
, a processing module, which allows to get the root mean square value
of the signal St. Its output signal De can be analog or digital, but it can
always be used by the downward systems.
The sensor hence is the first element of an information processing chain which
aims at collecting information and delivering them under an appropriate form.
The structure of this chain is depicted in Figure l.2.
Figure l.2 structure of the information functional chain
Conventional Sensors
The conventional sensors can be divided into different families:
, angular position sensors: two types of measures of the angular posi-
tion exist: the absolute measure and the relative measure. The axis of
the sensor is mechanically attached to the axis whose angular position
must be determined by means of a fiexible coupling. The rotation of this
latter axis causes the rotation of the axis of the sensor, whose angle shift
can be measured. The output signal of such sensors can be:
- Logic: two types of such sensors exist:
* Incremental rotary encoders, which provide a relative mea-
sure of the angular position. A disk pierced with regularly dis-
posed holes is fixed on the axis of the sensor and hence turns at
the same velocity as the axis whose angular position must be
determined, and light emitting and receiving diods are located
on both sides of the disk. The emitted light goes through the
holes of the disk and generates an analog signal when it reaches
the receiving diods. This signal is amplified, converted into a
square signal by means of a trigger, and then transmitted to a
processing module by means of an electronic device. An incre-
mental rotary encoder is depicted in Figure l.3, the disk of such
a sensor is depicted in Figure l.4, and the timing diagrams of
the outputs of the related receiving diods are depicted in Fig-
ure l.5: the output variables a and b correspond to the outputs
of the two receiving diods whereas the variable a D b is used
to determine the angular position of the disk. The following
variables can be used to determine the rotation direction:
Positive_rotation = a . b+ b . a+ a . b+ b?a
Negative_rotation= a . b+ b a+ a . b+ b . a
Figure l.3 an incremental rotary encoder
* Absolute rotary encoders, which provide an absolute mea-
sure of the angular position. Their disk has n concentric rings
divided into parts which are alternatively translucent and opa-
que. An optical emitterreceiver couple is associated with each
ring7 the inner ring corresponding to the least significant bit
whereas the outer ring corresponds to the most significant bit.
The binary code obtained allows to know the absolute position
of the axis. The disk of such a sensor is depicted in Figure l.6.
Figure l.4 the rotary disk of an incremental rotary encoder
Figure l.5 timing diagrams of the outputs of the related receiving diods
- Analog: three types of such sensors exist:
* Resistive potentiometers: the variation of the angle of the
axis of the potentiometer modifies the resistance of the poten-
tiometer. The measure of the voltage across the potentiometer
hence allows to determine the angular position of its axis. A
resistive potentiometer is depicted in Fig
購物車/收銀台(0) | 在線留言板
| 付款方式
| 運費計算
| 聯絡我們
| 幫助中心 |
加入書簽
HOME
新書上架
