User Manual

4/16 Bosch Rexroth AG Mobile Hydraulics
Dual Path Control DPC
RE 95 325/03.04
Additional Functions
During the commissioning of the vehicle, three different func-
tions can also be activated to facilitate control of the travel
behavior:
• Setpoint repeat function
The setpoint repeat function determines the way in which the
maximum travel speed is increased or reduced step by step
using the pushbuttons in the joystick.
When the setpoint repeat function is switched on, the travel
setpoint is increased or reduced constantly as long as the
corresponding button is pressed.
When the setpoint repeat function is switched off, the
travel setpoint is increased or reduced once every time the
corresponding button is pressed.
• Load Limiting Control
The load limiting control prevents overload of the diesel
engine when the demanded hydraulic power is increased,
when negotiating a steep ramp, for example.
It does this by comparing the current speed drop of the
diesel engine with a definable limit value. If this value is
exceeded, the load limiting controller intervenes and reduces
the demanded pump outputs.
• Synchronization control for controlled straight line driving
The speed ratio of the left and right drives determined
by the steering angle setpoint is kept constant by the
synchronization control. This is achieved through the use of
sensors which detect the actual speeds of the left and right
hydraulic motors.
Steering Behavior
Steering behavior is controlled by two variables:
• The steering direction is determined by the joystick.
• The steering behavior, that is to say, the reaction to a change
in the steering direction, is determined by the actuation of
the PWM outputs and by a modifiable curve. Five curves are
available, from linear to maximum progressive.
The joystick is in the neutral position in terms of travel direction
(forwards or backwards) and steering direction (left or right),
if it is positioned within a user-definable range around the zero
position. This range is called the dead band. The dead band
can be set for both deflection directions separately.
When the joystick is in the neutral position, the PWM outputs
for the forwards and backwards travel directions for actuat
-
ing the proportional solenoids of the left and right pumps are
turned off.
If the joystick is moved sideways to a position outside the dead
band, the current at the relevant PWM outputs (for forwards or
backwards travel direction) changes according to the deflec
-
tion direction (left or right) of the joystick and the selected
curve. The corresponding proportional solenoids of the left and
right pumps are actuated.
If the joystick is moved sideways beyond a point at which
resistance can be felt, this causes the drives to run in opposite
directions, to achieve the smallest possible turning radius.
The point at which this resistance can be felt can be set for all
deflection directions of the joystick separately.
The steering function has priority over the travel setpoint.
Therefore, with maximum travel setpoint and simultaneous
steering, the travel speed is reduced due to braking of the drive
on the inside of the curve.
Figure 2: Dual path control DPCA: How it works
Set speed of diesel engine
Actual speed of diesel engine
Actual speed of left motor
Actual speed of right motor
up/down
CAN
Analog
setpoint
Drive
setpoint
Safety
switch
CAN
Analog
setpoint
Steering
setpoint
Emergency
Stop
Acceler-
ation
behavior
Steering
behavior
linear/
progressive
Speed
controller
Pump
Left
Pump
Right
Motor
Left
Motor
Right
Load Limiting
Control
E
M
E
R
G
E
N
C
Y
S
T
O
P