Galil DMC-1700 Manual Do Utilizador

G(s) = [16 + 0.144s + 1000/s} 

∗ 250/ (s+250) 

The notch filter has two complex zeros, Z and z, and two complex poles, P and p. 

The effect of the notch filter is to cancel the resonance affect by placing the complex zeros on top of the 
resonance poles.  The notch poles, P and p, are programmable and are selected to have sufficient 
damping.  It is best to select the notch parameters by the frequency terms.  The poles and zeros have a 
frequency in Hz, selected by the command NF.  The real part of the poles is set by NB and the real part of 
the zeros is set by NZ. 

The most simple procedure for setting the notch filter, identify the resonance frequency and set NF to the 
same value.  Set NB to about one half of NF and set NZ to a low value between zero and 5. 

The ZOH, or zero-order-hold, represents the effect of the sampling process, where the motor command is updated 
once per sampling period.  The effect of the ZOH can be modeled by the transfer function 

H(s) = 1/(1+sT/2) 

If the sampling period is T = 0.001, for example, H(s) becomes: 

H(s) = 2000/(s+2000) 

However, in most applications, H(s) may be approximated as one. 

This completes the modeling of the system elements.  Next, we discuss the system analysis. 

To analyze the system, we start with a block diagram model of the system elements.  The analysis procedure is 
illustrated in terms of the following example. 

Consider a position control system with the DMC-1700/1800 controller and the following parameters: 

Kt = 0.1 

Nm/A 

Torque constant 

J = 2.10-4 kg.m2 

System moment of inertia 

R = 2 

Ω 

Motor resistance 

Ka = 4 

Amp/Volt 

Current amplifier gain 

KP = 12.5 

 

Digital filter gain 

KD = 245 

 

Digital filter zero 

KI = 0 

 

No integrator 

N = 500 

Counts/rev 

Encoder line density 

T = 1 

ms 

Sample period 

The transfer function of the system elements are: 

M(s) = P/I = Kt/Js2 = 500/s2  [rad/A] 

Ka = 4  [Amp/V] 

Kd = 0.0003  [V/count]