Elastic suspension of the LM has rigidity [k.sub.v] = 153291 N/m, coefficient of viscous friction
[b.sub.v] = 44.9 kg/s.
Two typical faults in actuators of UM were considered: fault caused by changing of viscous friction
moment and error in the sensor, which measures the position of output shaft of gear.
At low temperature viscous friction
is a significant contributor to the total power requirement of the pump.
Simulations performed with viscous friction
near to zero revealed no improvement of the response time.
As far as the effective low area is concerned, this is a consequence of the greater viscous friction
in the radial flow, which is observed when the clearance becomes narrower, reducing the mass flow rate.
In CP (1), for convenience of writing and analysis, the following notations are accepted: [T.sub.d] = [+ or -] [[beta].sub.C]/[c.sub.12] is time constant due to viscous friction
; [T.sub.y] = 1/[[OMEGA].sub.12] is the time constant of elastic vibrations.
However, the behavior of the identified viscous friction
coefficient [??]([t.sub.k]), shown in Figure 6(b), may disagree with the actual phenomenon in which the viscous friction
is proportional to the velocity and reaches zero at zero angular velocity.
where, v is the relative velocity between the two surfaces, [F.sub.c] is the coulomb friction level, [F.sub.s] is the level of the stiction force, [v.sub.s] is the Stribeck velocity, [[sigma].sub.0] is the stiffness, [[sigma].sub.1] is the viscous damping coefficient, and [[sigma].sub.2] is the viscous friction
It is assumed that the following types of faults are possible in the actuators of MM: [d.sub.1]-fault caused by an increase of moment of viscous friction
in the link of manipulator; [d.sub.2]-fault caused by an increase of moment of viscous friction
in the actuator; [d.sub.3]-fault caused by the change of active resistance of rotor circuit of DC motors (for example, in case of significant changing of temperature).
Parameters of PC servo motor and tacho generator Motor constants Symbol Rated Voltage [U.sub.n] Stream idle [I.sub.0] Permissible maximum current [I.sub.max] Inductance coil [L.sub.a] Winding resistance [R.sub.a] Rated engine speed n Torque constant [K.sub.t] Constant voltage [K.sub.e] Mechanical time constant [T.sub.m] Moment of inertia of the engine J Viscous friction
B Motor constants Value Rated Voltage 12 V Stream idle 0.044 A Permissible maximum current 1.5 A Inductance coil 0.0003 H Winding resistance 2.5 [OHM] Rated engine speed 5800 rpm Torque constant 0.0195 Nm/A Constant voltage 0.01957 Vs/rad Mechanical time constant 0.012 s Moment of inertia of the engine 17.6-[10.sup.-7] kg[m.sup.2] Viscous friction
1 x [10.sup.-6] Nms/rad
also creates a force to resist motion, but the effect is proportional to speed.
where [u.sub.A] represents the input voltage, [R.sub.A] is the electric resistance, [i.sub.A] is the armature current, e is the counter-electromotive force, L is the electric inductance, [K.sub.m] motor torque constant, [K.sub.e] ([K.sub.m] = [K.sub.e]) electromotive force constant, [K.sub.d][[omega].sub.m] ([K.sub.d] = b) damping torque given by the loss of magnetic field and viscous friction
in the motor's bearings, [M.sub.m] is the motor's torque, [M.sup.r.sub.r] is the resistant torque reduced in the axle of the motor, [I.sup.r] is the moment of inertia of the rotor and [i.sub.total] = [i.sub.reducer][i.sub.transmission].