ElmoMC SimplIQ Software Manual - Manual (Page 225)

SimplIQ Software Manual The Controller
MAN-SIMSW (Ver. 1.4)
15-7
15.3 The Gain Scheduling Algorithm
Gain scheduling (GS) is implemented for speed and position controllers, so that the
controller parameters — speed controller KI and KP, position controller gain, and high-
order filter links — are changed automatically with the working point of the servo drive.
Gain scheduling solves the following problems:
ƒ
Low-resolution position sensor:
When the position sensor has a low resolution, the speed is derived from the position
data with a large time delay, typically half the time between consecutive encoder pulses.
The delay in speed measurement is a potential risk to controller stability. In order to
maintain stability at low speeds, the controller gains are reduced. For high speed, the
controller achieves its full possible bandwidth. The
SimplIQ drive can schedule the
controller gains automatically, as a function of the command to the speed controller. In
speed unit mode, the command to the speed controller is a function of the reference
generator only. For the position control modes (UM=4, UM=5), the reference to the
speed controller is the sum of the position command derivative and the output of the
position controller.
ƒ Load and posture variations:
When controlling an articulated manipulator, the inertia of some manipulator motors
varies greatly with the posture of the manipulator. The resonance frequency may also
vary considerably with changing posture or load conditions. Using gain scheduling, one
can switch the active controller parameters as a function of posture and load.
The following table describes the programming of 63 controller parameter sets:
Parameters Name Description
KG[1]…KG[63] SpeedKiTable SpeedKiTable[k] is the speed KI gain for the k-th
controller.
KG[64]…KG[126] SpeedKpTable SpeedKpTable[k] is the speed KP gain for the
k-th controller.
KG[127]…KG[189] Position KpTable Position KpTable[k] is the position KP gain for
the k-th controller.
KG[190]…KG[252] SpeedIndexTable Used for automatic gain scheduling ( section
15.4 ).
KG[253]…KG[315] ParameterTable1 ParameterTable1[k] is the k
1
parameter for the
second-order element of the k-th controller.
KG[316]…KG[378] ParameterTable2 ParameterTable2[k] is the k
2
parameter for the
second-order element of the k-th controller.
KG[379]…KG[441] ParameterTable3 ParameterTable3[k] is the k
3
parameter for the
second-order element of the k-th controller.
KG[442]…KG[504] ParameterTable4 ParameterTable4[k] is the k
4
parameter for the
second-order element of the k-th controller.
Table 15-5: Programming Sets of Controller Parameters for Gain Scheduling