The Robot Power Scorpion XXL is a flexible high-performance
two-channel motor controller for small to medium mobile robots such as
competition firefighting robots, sumo, robotic combat, theater props,
inspection and other applications. It may be used on robots up to as much
as 90 pounds or more as long as the motor current limits are respected.
The Scorpion XXL is suitable for other applications as well including
lights, hydraulic valves and other static non-robot uses.
Features
The Scorpion XXL contains the following features:
- 20A continuous current (45A peak) each on Left
and Right channels.
25A continuous current with fan cooling
- 6.0V to 28V battery
voltage
- Full current limiting and
over temp limiting. Nearly blow proof!
- Size: 3.27� x 2.27� x
.5�
- Weight: 1.8 oz (52g) with
servo leads but without enclosure
- Two R/C input leads and
one pin header for:
- Steering/Throttle or
Left/Right Control - fully reversible H-bridge channels
- Flip Control - reverses
controls if robot is flipped over (optional)
- 2 Indicator LEDs for
Left/Right speed and direction. A status LED shows the R/C signal
status and other information
- Left/Right channel mixing
or separate channel control option
- Brake/Coast at zero speed
option
- Linear/Exponential
steering response option
- Lipo battery cutoff option
- Switching style 5V
regulator eliminates battery voltage worries and provides increased
current on the 5V rail for the newer 2.4GHz radio receivers. Works
without jumpers from 6V to 28V
- Receiver battery
eliminator circuit (BEC) standard � may be disabled. This can
provide up to 200 mA of current at 5V to
the RC receiver and other attached electronic circuits.
- Failsafe shuts off motors
if R/C signal is lost
- Calibration function to
match Scorpion to your radio or other signal source - settings
stored in EEPROM
- FLASH-based
microcontroller with upgradeable software via in-circuit programming
header
- Remote power switch
connections to turn unit off without breaking the main power
connection
An optional
plastic enclosure is offered to protect Scorpion XXL from environmental
contamination.
The enclosure is also used to mount the cooling fan for the XXL.
The enclosure and cooling fan are offered as user-installed
kits. The user is free to customize them as needed for the individual
application.
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Scorpion
XXL Controls
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Control Features
The Scorpion XXL software is designed to work with most R/C systems out of
the box. The most common options are set up as the default so no complicated
configuration, calibration, or programming is required. The controls shown
in the image above, left to right, are: BEC jumper, RC wires for
Steering/Throttle or Right/Left channels, Option DIP switches, Status LED
and the Calibration button.
The following configuration options are available in the Scorpion XXL
software:
- Mixing
- Switching the "M" switch to ON activates channel mixing.
This function allows one radio channel to be used as the
"throttle" control and one as the "steering". This
allows driving of differential drive robots in a natural and intuitive
way using a single transmitter stick. The OFF position allows
independent control of each motor output. This is also known as
"tank" mode. Tank mode is also suitable for programmed control
by microcontrollers etc. which can do any needed channel mixing
internally.
- Brake/Coast
- Switching the "B" switch to ON activates Brake Mode. In
this mode the motor leads are shorted together when a zero speed is
commanded. This provides a strong electromagnetic braking action to
the motor. The OFF position activates Coast Mode. In this mode the
motor leads are disconnected at zero speed. This allows the motor to
more gently coast to a stop. The physics of the individual application
will decide which setting is best.
- Exponential
- Setting the "E" switch to ON actiates
Exponential mode - OFF activates Linear Mode. In Linear Mode at 50%
stick throw the output voltage will be set to 50% as well. Under
Exponential Mode the output response is related to the input via an
exponential curve . This allows a softer response around the center
point while still giving full power at the extremes of the control
range. This setting helps when driving robots by eye as it makes
control smoother when giving small control inputs. Throttle response
is always linear. In Tank Mode both channels have exponential
response.
- Lipo Cutoff
- the "L" switch controls the Lipo
battery safety cut-off feature. When switched ON the Lipo cut-off is activated if OFF the battery
voltage is ignored. Lithium chemistry batteries can be damaged if they
are over-discharged. The Lipo cut-off
feature will disable the outputs if the battery voltage falls below
3.0V per battery cell. The system determines the cell count at
power-on and calculates the cutoff voltage from that. If the battery
is mostly discharged when the unit is powered on an incorrect cell
count may result and the cut-off function may not work properly
allowing excessive discharge of the battery.
- BEC
- the internal 5V regulator on the Scorpion XXL is connected to the
power wires on the servo leads by default. This allows the Scorpion to
provide power to the R/C receiver or other external circuits and
eliminates the need for an external R/C receiver battery. Cutting the
BEC jumper on the PC board disables this function and allows a
separate 5V supply to power the R/C signal source (receiver or
microcontroller).
- Calibrate
- a pushbutton switch is provided to activate the Scorpion XXL
calibrate mode. This mode is used to map the radio or other RC signal
source to the full range of motor outputs. The range of values sent by
the radio system or microcontroller is recorded and the Scorpion XXL
stores the values in non-volatile memory and retains them permanently.
It is also possible to reset the values to the factory defaults.
- Flip
- Certain robot applications need to reverse the forward/reverse
response under user control. The most common situation is when the
robot is flipped upside down. If the control response is not reversed
driving is very difficult as the robot responds in a reverse direction
to normal control inputs. By default the Flip function is controlled
by an R/C channel. The landing gear switch on an aircraft style radio
or the 3rd channel on a pistol style are commonly used to activate
this function. An alternative configuration is to use a binary signal
to activate the motor flip function. In this configuration a switch is
connected between the signal wire and the ground wire on the Flip R/C
lead. When the switch is closed the flip function is activated. A
logic level input from a microcontroller may also be used as long as
the two units share a common ground wire.
A Documentation for the Scorpion XXL with details on setup and
operation of the controller will be available soon from the downloads page. Contact us for any detailed
questions about setup or use of the XXL.
Robot Power offers the Scorpion XXL in
fully assembled units ready to install and use. Check the Web store for details on prices and special offers.
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