How Can Steer Accuracy Be Improved? Minimizing Mechanical Plays - Zapi EPS-AC0 SWs&ENC User Manual

7.11 How can steer accuracy be improved? Minimizing mechanical plays

The highlight of a correct installation for a steering system with
potentiometers is to neutralize the mechanical plays. Due to the fact we have
only a potentiometer in the tiller side, the mechanical play to be neutralized is the
one in the shaft of the potentiometer at the tiller. In fact the accuracy for pursuing the
commanded position is only effective in case no mechanical play exists between the
coupled parts. Obviously potentiometer is a fragile device and mechanical
connection of its shaft with a rigid frame requires a joint clearance or slotted hole to
avoid damage. This joint clearance is absolutely negative because it determines that
a certain tiller position corresponds to different positions for the pot's shaft (all the
positions inside the joint clearance). The consequence is a poor accuracy of the
pursuing at the commanded position. An effective countermeasure to neutralize this
mechanical dead zone in the potentiometer is to use a spring to keep the shaft in
contact with an end-stroke inside the joint clearance (see figure below).
Neutralizing mechanical plays is strongly recommended because eps_ac0 makes
possible a big accuracy in the pursuing of the commanded voltage (see 11.4.4.6-7,
parameter change KP and POS ACCURACY) but only the absence of
mechanical plays between coupled parts gets this potential accuracy
effective.
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Figure 7–1
AEMZP0EA - EPS-AC0 SWs&ENC - User Manual