B. Command and Control Circuits
Our instrumentation allows us to command and control
the 2DOF platform. A Microsystems based on Pic18F4550
microcontroller was realized for driving the whole
instrumentation. The choice of the microcontroller is due
to the availability of a sufficient number of input pin and a
USB communication protocol. Our development board
contains a microcontroller, an USB and serial port, a 5V
power supply for all inputs and outputs. This card has been
designed in order to be so polyvalent, so it can be used for
the acquisition of any analog or digital signals and
transmitted signals via the USB or serial port. Fig.5 shows
the development board.
The four stepper motors are driven with the
Microcontroller thought an adaptive power circuit made
with a stepper motor controller ‘L297’ from
STMicroelectronics to convert a time delay into a stepper
sequence and allow us to choose the rotation, coupled with
a dual full bridge driver ‘L298’ from STMicroelectronics
to supply the motors with 24V DC and sufficient current
and make them able to rotate in two directions.
und it useful to insert an accelerometer for measuring the
angle of inclination; this measurement is taken from the
measurement of static acceleration.
For the inclination measurement, we use an ADXL335
accelerometer from Analog Device as a tilt sensor. The
monolithic IC is mounted on a breakout board from
Mikroelektronika which contain a signal conditioned
voltage outputs made with a low pass filter with a 50Hz
cut-off frequency and three rail-to-rail op-amps as voltage
follower for impedance matching.
Because our accelerometer is a 3 axis, we use a tripleaxis
tilt calculation to perform the tilt sensing using the
static acceleration due to gravity. With classical method of
rectangular (x, y, z) to spherical (