5.3.1.2
Speed limiting options
The DX System offers many options that limit the available Speed Demand range to
suit safety requirements as well as the preferences of the user. These options can be
grouped into five categories:
•
the Maximum Motor Volts parameter
•
the Input Demand Scaler parameter
•
the Speed @ Maximum parameter
•
the Speed Pot function
•
the Speed Limit function.
100
%
10
0%
10
0%
Speed @
Maximum
Speed @
Minimum
Speed Pot
(0-100%)
Speed Limit
(0-100%)
10
0%
Chair physical top speed*
Zero speed
100%
PM Input
De
ma
nd
Sc
aler
100%
Chair speed @
100% Joystick
Deflection
Joystick
This line is pushed down
by the dynamic speed
limiting function that has the
lowest momentary value
(in this example Speed Pot)
Static speed limit
Dynamic speed
limiting functions
momentary value
* The 'Chair physical top speed' is limited by either the available battery voltage or the
Maximum Motor Volts parameter, whichever has the lowest momentary value.
The
Maximum Motor Volts
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: Issue 1 – October 2007
54
parameter (4.3.2.12) sets the maximum Voltage that the
Power Module will apply to the motor. The
powerchair manufacturer
can use this
parameter to limit the 'Chair physical top speed' to a calculated speed limit for a
particular chair type (for specific motors and a specific wheel diameter).
The
Input Demand Scaler
parameter (4.3.2.13) allows the
Power Module
to scale
down the Speed Demand that the UCM requires. A reduced Speed Demand creates
extra steering headroom if a turn is requested at full speed (because steering is
normally done differentially, with one wheel turning faster than the other one).
The
Speed @ Maximum
parameter can be adjusted by the
dealer
to set a maximum
UCM Speed Demand value for the chair, suitable for a specific user. Every Drive
Profile has its own Speed @ Maximum setting for forward, reverse and turning to allow
different speed limits for different circumstances (indoors, outdoors).
For more information on Drive Profiles, see section 5.3.2.
