HS50_advance_level 2 - 第154页
07/2002 Editio n Student G uide HS -50 Advanc ed II 6 Cont rol & C ommun icatio n 24 3RVLWLRQ &RQWURO Under the o peration al mod e of pos ition control an attempt is ma de to retain a progra mmed po si- tion. …
Student Guide HS-50 Advanced II 07/2002 Edition
6 Control & Communication
23
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This means moving the axis mechanism out of the current position in a specified destination po-
sition under controlled acceleration and speed control. Here the destination position, the acceler-
ation, the deceleration and the speed can be varied.
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The end signal is generated, when the position deviation is in the allowed range (value in
ACHS.MA, normally 13 digits).
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By crossing the positioning corridor (digit value in ’mode 2’ in ACHS.MA, normally 10 digits) the
set point speed is set to zero (Vnull) and the position control is activated. This means the micro-
processor calculates the acceleration and deceleration curve to a position, which is 10 digits be-
fore the real target position.
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The Overshoot counter is activated when the axis crosses the target (setpoint) position for the first
time. You can check this overshoot because axis test box is triggered with "actual position is nom-
inal position signal". The End signal is given by the axis card to the Machine Controller once the
apex of the overshoot is within the Allowed Deviation of position. The end signal allows the ma-
chine controller to initiate the next movement or function.
Position counting
Overshoot
counting
Time
Time
Time
mechanical movement and position counting
ACTUAL-, is NOMINAL position signal
End signal
Allowed deviation of position
Allowed deviation of position
positioning
occurrence
position
controlling
X
position
Axis move up from
here with minimum
speed and with
reduced P
gain
When the mechanic move
the first time across the
target position the
“actual position is nominal
position signal” is triggered
the overshoot counter starts
The overshoot counter monito
r
a 6 digit maximum
End signal is triggered
position controlling start
s
and the next axis starts
For the P&P head is the allowed deviation of position 2 digit
Positioning
corridor
07/2002 Edition Student Guide HS-50 Advanced II
6 Control & Communication
24
3RVLWLRQ&RQWURO
Under the operational mode of position control an attempt is made to retain a programmed posi-
tion. The target (setpoint) position stored in the main memory of the microprocessor is compared
with the actual position (counter register). If a position deviation is detected (the target or setpoint
position is not equal actual position) then the servo amplifier is actuated via the V nom in such a
way that the mechanism returns back to the programmed position (target or setpoint position).
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On short travel distances and at SIPLACE HS-50 X and Y axis positioning very often occurs with-
out an overshoot. The end signal is triggered 10 ms after the axis first crosses the allowed devia-
tion of position. If within this time the axis moves out of allowed position deviation the 10 ms timer
is deactivated.
ACTUAL-, is NOMINAL position signal
mechanical movement and position counting
End signal
Time
Time
Time
ACTUAL-, is NOMINAL position signal
mechanical movement and position counting
End signal
Time
Time
Time
Position counting
Allowed deviation of position
Allowed deviation of position
Time for “SSK” (10 ms)
is used for the end
signal at asymptotic
approach
positioning
occurrence
position
controlling
If there is no overshoot we get the end signal by asymptotic approach.
From here the Axis
moves with minimum
speed and with
reduced P
gain
End signal is triggered
position controlling
starts and the next axis
starts
X
position
Positioning
corridor
Student Guide HS-50 Advanced II 07/2002 Edition
6 Control & Communication
25
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The diagram above represents the key signals that can be monitor using an oscilloscope, axis test
box and axis test adapter.
On the axis test box there is a push button switch, this switch should normally be pressed. When
it is the End Signal waveform is measured by connecting the oscilloscope BNC lead to the adapter
card. In this state the ’End Signal’ connection at test box will not output the actual End Signal but
instead output the signal given when the target position is passed by the axis for the first time, this
is know as the ’Positioning Time’. If the push button is released the signals given are reversed.
On the diagram above we can see that the difference between ’Positioning Time’ and ’End Signal’
is determined by the size and quantity of the overshoots. This signal can be monitored at the test
box by connecting to the ’Position Deviation’ connector.
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