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Ch69-I044963.fm Page 342 Friday, July 28, 2006 1:50 PM
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342 Page 342 Friday, July 28,2006 1:50 PM
Digital-Signal-Processors have previously had a serious limitation in control applications; lack of
suitable I/O. Motorola's DSP56F803 processor and its newer version are designed to fulfil a gap
between traditional Micro Controllers and high speed DSPs [Freescale 2005], These kinds of DSPs
are often called a hybrid controller. Main features which make this processor suitable for this
application are; a CAN 2.0B module to connect controller to other modules in the system (joystick,
other controller modules, etc.), a PWM-module to control proportional valves and ADC-channels to
measure pressures. One nice feature is also a quadrature decoder interface which gives possibility to
connect incremental encoder directly to the controller without any extra electronic. To achieve a
reliable current control of proportional valves it is necessary to close the current control loop via a
hybrid controller. This control solution gives more options to improve long term stability and
diagnostic of valves. Because this hybrid controller has not enough l/O-capacity it is necessary to
distribute the control of this sub-system. Best and most flexible solution is to use one hybrid
controller per DOF. The preliminary tests show the speed of this hybrid controller is enough to realize
needed control algorithms, especially when applied only on one DOF. Based on tests the estimated
computation time is approximately lms. This guarantees that 2ms sampling time of the control loop
can be used, which is short enough for these kinds of applications and needed algorithms.

CONCLUSIONS
According to preliminary simulations and estimations the following conclusion can be presented: It is
possible to reduce energy consumption of forward booms in unloading work with proposed control
system about 25% in certain work cycles. Only pressure sensors are needed. Hybrid controller has
suitable I/O and computation capacity for computation of one DOF.

FURTHER STUDIES
In the next stage the study is extended to loading process. Then the jib cylinder is in the same role as
the lift cylinder in unloading. Experimental studies will be also carried out. If results are still
promising the study is extended to deal with all four DOFs of the boom.

REFERENCES

Balluff, www.balluff.com, 2005
BoschRexroth www.boschrexroth.com, 2005
Dynisco, www.dynisco.com, 2005
Freescale, www.freescale.com, 2005
Kannisto, S. & Virvalo, T. 1, 2002. Approximate velocity feedback using estimated volume flow rate
of servo valve. 8th Mechatronics Forum, Netherlands, 24-26 June, 2002. s. 764-774.
Kannisto, S. & Virvalo, T. 2, 2002. Approximate Velocity Feedback Using Hydraulic Valve Flow
Modelling. 5th JFPS, Nara 2002, November 14, 2002. 2. Japan, s. 501-506.
Kannisto, S. & Virvalo, T. 3, 2002. Valve Manufacturer Specifivation Based Hydraulic Velocity
Control. IMECE2002, November 17-22, 2002, New Orleans, Louisiana, USA. 2. 7 s
Moog, www.moog.com, 2005
Parker, www.parker.com/iqan/. 2005
Sauer-Danfoss, www.sauerdanfoss.com, 2005
Ultronics, www.ultronics.com, 2004