User guide

B. Basic controlling principles
B−37
Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
m
delta
= m
current tool mass
+ m
current workpi ece mass
 m
ident.
m
delta
= m
current tool mass
+ m
current workpi ece mass
 (m
workpi ece mass ident.
+ m
workpi ece mass ident.
)
F
piston
= F
setpoint
+ F
0
+ m
delta
* g * sin α
In the simplest case, the following applies:
m
current tool mass
= m
tool mass ident.
m
workpi ece mass ident.
= 0 kg
This simplifies calculation for:
m
delta
= m
current workpi ece mass
F
piston
= F
setpoint
+ F
0
+ m
current workpi ece mass
* g * sin α
What does this mean in terms of force control?
It is not necessary for the mass m
ident
specified during
identification to be exact, since the force F
0
required for
compensation is identified.
If the drive is not mounted horizontally (
α š 0° ), it is im
portant to specify the mass changes precisely. Since the
controller calculates a compensation force based on the
specified mass, an error in the mass specification will lead
to a systematic deviation from the force setpoint value
F
setpoint
.
F
piston
= F
setpoint
+ F
0
+ (m
delta
+ m
error
) * g * sin α
 Error F will then be:
F = m
error
* g * sin α