20
Elevation 1+
© 2011 Kinesys Projects Ltd
10
Position Controller
The advanced position controller inside the Elevation 1+ unit takes the move profiles
that are sent to it by the controller and translates them into movement commands for the
internal drive electronics. The control software use a closed loop ‘PID’ system to
regulate the speed and position of the hoist at any given moment. The Proportional,
Integral and Derivative (PID) sections of the control loop each have a unique effect on
the accuracy and smoothness of the final motion and consequently the ‘tuning’ of these
parameters can be crucial to the correct functioning of the unit.
NOTE: Only adjust these parameters if you are confident of your abilities to tune
the system. The Elevation 1+ is supplied with a default set of parameters which are
designed to work in the vast majority of situations and environments. When tuning
the drive be sure that the device and load are free and safe to move and that there
is physical room to allow for unexpected movement and behaviour.
P1 - Proportional Gain
(Default value 25000)
The proportional gain in the system creates an output that is proportional to the position
following error (the difference between its current location and its ideal location). This
gain is not affected by speed and ramps and provides the majority of the feedback
require to keep the system working correctly.
P2 - Integral Gain
(Default value 1500)
The integral gain creates an output that is proportional to the sum of the errors that have
occurred during the system operation. Its effect is to reduce small steady-state position
errors. Integral gain has most effect in ensuring that the desired speed is followed as
accurately as possible and therefore applies most during the cruise phase of a move
profile.
P3 - Derivative Gain
(Default value 00250)
The derivative gain is a function of the measured velocity and improves the high
frequency closed loop response. Derivative gain is the most volatile of the three settings.
Its effect is most pronounced during the acceleration and deceleration phases of a move
profile. An incorrect value for this setting can lead to instability during movement and
potentially erratic behaviour.
P4 - Min Speed Output Value To Drive
(Default value 50 = 1hz)
The minimum raw speed value that can be sent to the drive. This value is measured in
units of 0.02Hz. Used to set the minimum drive speed required to obtain movement. This
value is used with the max speed output parameter to limit the range of the PID loop.
The Elevation 1+ Firmware only uses the lower 16 bits as an unsigned integer.
P5 - Max Speed Output Value To Drive
(Default value 5000 = 100hz)
The maximum raw speed value that can be sent to the drive. This value is measured in
units of 0.02Hz. Used to set the maximum drive speed that may be permitted. This value
