User manual

RP6 ROBOT SYSTEM - APPENDIX
7. With every program, the motors just accelerate very shortly up to a
high speed, and then immediately stop. Subsequently four red LEDs
start blinking!
● The simplest possibility: You loaded a self-written or modified example pro-
gram to the robot and forgot to execute “powerON();” before starting the
motors!
● Did you modify the software (especially the library) in any way? Try some
other programs and the self-test program.
● If other programs and the self-test behave in a similar way: check the out-
put on the serial interface! Additionally to the 4 red blinking LEDs, the sys-
tem outputs an error message which you can look at in the terminal. Most
likely, the encoder system may cause this malfunction. Sometimes the ad-
justing collars, fixing the encoder wheels, may have detached, causing the
gearwheels to drift away from the sensors. In this case the encoder system
will stop delivering feedback signals! By the way: we provided the encoders
with potentiometers (=variable resisters) to adjust the sensors (use a fine
1.8mm slot screwdriver or a suitable cross slot screwdriver! BUT BE VERY
CAREFUL (for RP6, RP6v2 is quite robust and easy to adjust). The self-test
program will show if the encoders work properly. We provided the program
with a special mode (c - Duty Cycle Test) to check the duty cycle for the
square wave signal. You can activate WAVEFORM DISPLAYS there from
the “Displays” tab to take a look at the Encoder Signals. 50% duty cycle
(50:50) is optimal. However, deviations and fluctuations between 25 and
75% can be considered as tolerable. Most of the duty cycle values should be
in the range of 30 up to 70%. During tests the test-program will deactivate
the motor-control and run the engines at a fixed PWM-value. Speed meas-
urement values will be shown in encoder counts per 200ms.
● Maybe the encoder wheels have been damaged? For instance by oil or lub-
rication grease as described previously?
● Check the cables to the encoder system for possible damage, e.g. by using a
Multimeter (switch the robot off and check every single wires for connection
between both ends and for short circuits to its neighbours!)!
● Check the tiny IR reflection sensors of the encoders for polluted areas.
● The LEDs will also start blinking as soon as one motor is (or both motors
are) malfunctioning – so check the wiring and the printed circuit board, es-
pecially near the motor drivers.
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