Independent thesis Advanced level (professional degree), 20 credits / 30 HE credits
The objective of this thesis is to derive an analytical model representing a reduced
form of a mine hoist hydraulic braking system. Based primarily on fluid
mechanical and mechanical physical modeling, along with a number of simplifying
assumptions, the analytical model will be derived and expressed in the form of a
system of differential equations including a set of static functions. The obtained
model will be suitable for basic simulation and analysis of system dynamics, with
the aim to capture the fundamentals regarding feedback control of the brake
The thesis will mainly cover hydraulic servo valve and brake caliper modeling
including static modeling of brake lining stress-strain and disc spring deflectionforce
characteristics. Nonlinearities such as servo valve hysteresis, saturation,
effects of under- or overlapping spool geometry, flow forces, velocity limitations
and brake caliper frictional forces have intentionally been excluded in order not to
make the model overly complex. The hydraulic braking system will be described
in detail and basic theory that is needed regarding fluid properties and fluid
mechanics will also be covered so as to facilitate the reader in his understanding
of the material presented in this work.
Overall, the scope of this thesis is broad and more work remains in order
to complement the model of the system both qualitatively and quantitatively.
Although not complete in its simplified form and with known nonlinearities aside,
the validity of the model in the lower frequency domain is confirmed by results
given in form of measurements and dynamic simulation. Static analysis of the
brake caliper model is also verified to be essentially correct when comparing
calculated characteristics against actual measurements, as is also the case for the
static models of the brake lining and disc-spring characteristics.
2015. , 100 p.