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11.SELECTION
11-1 Specification symbol list
The following symbols are required for selecting the proper servo:
T
: Acceleration torque [N • m]
a
T
: Deceleration torque [N • m]
b
T
: Servo motor torque necessary for
Ma
acceleration
T
: Servo motor torque necessary for
Mb
deceleration
T
: Torque applied during servo motor stop
LH
T
: Load torque converted into equivalent
L
value on servo motor shaft
T
: Load torque converted into
LM
equivalent value on servo
motor shaft during stop
T
: Unbalance torque
U
T
: Load friction torque
F
T
: Load torque on load shaft
LO
T
:Continuous effective load torque
rms
converted into equivalent value
on servo motor shaft
J
: Load inertia moment converted
L
into equivalent value on servo
motor shaft
J
: Load inertia moment on load shaft
LO
J
: Servo motor's rotor inertia moment
M
N
: Servo motor speed
N
: Servo motor speed during fast feed
O
N
: Load shaft speed during fast feed
LO
V
: Moving part speed
V
: Moving part speed during fast feed
O
P
: Ball screw lead
B
Z
: Number of gear teeth on servo motor shaft
1
Z
: Number of gear teeth on load gear
2
Z
n
: Gear ratio
2
n =
Z
1
Speed reduced when n>1,
Speed increased when n<1
η
: Drive system efficiency
g
: Gravitational acceleration (9.8[m/s
µ
: Friction coefficient
π
: Circle ratio (3.14)
[N • m]
P
: Number of feedback pulses in
t
position control mode
[N • m]
f
: Input pulse frequency in position
control mode
[N • m]
f
: Input pulse frequency during fast
o
[N • m]
feed in position control mode
T
: Acceleration time constant of
psa
[N • m]
frequency command in
position control mode
T
: Deceleration time constant of
psb
[N • m]
pulse frequency command in
[N • m]
position control mode
[N • m]
K
: Position control gain 1
p
[N • m]
T
: Position control time constant (Tp=1/Kp)
p
K
: Speed control gain
v
T
: Speed control time constant (Tv=1/Kv)
v
∆R
2
[kg • cm
]
: Feed per feedback pulse in
position control mode
∆R
: Feed per command pulse in position
o
2
[kg • cm
]
control mode
2
[kg • cm
]
R
: Feed
[r/min]
P
: Number of input command pulses in
[r/min]
position control mode
[r/min]
ts
: Settling time in position control mode
[mm/min]
to
: Positioning time
[mm/min]
tc
: Time at constant speed of servo
[mm]
tR
: Stopping time in 1 cycle
∆ε
: Positioning accuracy
ε
: Number of droop pulses
∆θ
: Load shaft rotation angle per pulse in position
e
: Euler constant = 2.718278
∆S
2
: Feed per servo motor revolution
])
11– 2
motor in 1 cycle
control mode
[pulse/rev]
[pps]
[pps]
[s]
[s]
[rad/s]
[s]
[rad/s]
[s]
[mm/pulse]
[mm/pulse]
[mm]
[pulse]
[s]
[s]
[s]
[s]
[mm]
[pulse]
[degree/pulse]
[mm/rev]
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