Denso SMT7 Instruction Manual page 81

Chapter 4 Configuring the Joint Parameters
4.7.2.1 Parameter details
(1) Positioning loop gain
Set the response of the positioning loop. The positioning loop gain is a
dimensionless number, so it may be converted to the (1/s) unit according to the
following formula:
Positioning loop gain x 125/256 (1/s)
For example, positioning loop gain 32 is equivalent to 15.625 (1/s).
Increasing the positioning loop gain will reduce the positioning time. However,
increasing the gain exceeding the natural oscillation frequency of the connected
mechanism will easily bring vibration or overshoot. If the natural oscillation frequency
is 20 Hz, for instance, set the positioning loop gain to 20 (1/s), that is, approx. 41.
(2) Positioning loop feed forward gain
Set the speed feeding forward value of the positioning loop. Increasing the value
will reduce the positioning error and increase the system response. Setting 100 may
reduce the positioning error to almost 0 in constant speed operation. However,
setting an excessively high value may easily cause vibration or overshoot in the
system.
(3) Positioning error allowance
Set the positioning error allowance. If the actual positioning error exceeds the
specified allowance, an error will occur. The positioning error allowance should
satisfy the following formula:
[Positioning error allowance] > [Maximum motor speed (rpm)] x
(1.0-[Positioning loop forward gain (%)] x 0.01)/[Positioning loop gain] x 524288/1875
(4) Speed control linear gain
Set the response of the speed control system. Increasing the value will make it
possible to set a high value to the positioning loop gain, thereby increasing the
system response. The speed control linear gain to be set may be converted to the
speed response frequency (in Hz) according to the following formula:
Speed response frequency (Hz) = [Speed control linear gain] / [Motor rotor inertia
(kgm
2
) + Load inertia converted at motor joint (kgm
2
)] x [Drive current loop gain] / (2)
65
(Formula 4.7-1)
(Formula 4.7-2)
(Formula 4.7-3)