Page 355 - Mechatronics for Safety, Security and Dependability in a New Era

Ch69-I044963.fm Page 339 Friday, July 28, 2006 1:50 PM
Friday, July 28,2006
1:50 PM
Page 339
Ch69-I044963.fm
339
339
EMBEDDED DISTRIBUTED SUB CONTROL SYSTEM BASED
ON HYBRID CONTROLLER

M. Lammila, T. Virvalo and E. Lehto

Institute of Hydraulics and Automation, Tampere University of Technology
Tampere, Finland

ABSTRACT

Modern forest machines, like forward loaders and harvesters, are still manually controlled
hydraulically driven, but strongly computerized machines. There are some fully or semi automatic
functions, but most often a driver acts as a controller. Goals of improving energy utilization of
forward loader boom and at the same time intensify the control of the boom require a lot of
computation power. Modern hybrid controllers seem to be good solution to these kinds of
requirements and applications

KEYWORDS

Embedded controller, hybrid controller, hydraulic boom

INTRODUCTION
Natural development during last decade has brought more integrated electronics also into mobile
machines and their hydraulic components like valves, pumps, and actuators. Quite a flexible method
is to use components that can be connected to the control system via a data bus. However, very few
valves with field bus interfaces have been available in the past, BoschRexroth (2005), Sauer-Danfoss
(2005), Ultronics (2004). On the other hand machine builders have accepted field buses very well.
The CAN bus is one of the most common data buses used in real time fluid power applications,
especially mobile hydraulic control systems. Lately the manufacturers of hydraulic components have
also developed valves and accessories which are available with a CAN bus interface, Moog (2005),
Parker (2005). There are suitable sensors for fluid power applications like position, pressure, and
temperature sensors with the CAN bus interface, Balluff (2005), Dynisco (2005), Pepperl-Fuchs
(2005).

One important topic in R&D of mobile machines is the improving of energy utilization. Total power
levels, for instance, in forest machines are 150-200kW. Low efficiency leads to over-sizing of
components and heat problems as well as to poor economic results.