Hardware manual
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8. Conclusions.
The general conclusions from my work are not simple task, so I think the best would be if I present
my own opinion about every part or element on which I gained some new experience.
Firstly, my knowledge about motors was/is not too big, but personally I think that brushless DC
motors represent one of the most powerful and useful group of motors. At the first look, the control
of this kind of the motors seems very hard and complicated task - especially when we compare it to
a normal DC motor, where it is just enough to connect power to make it working. But, at the same
, starting from a silent during operation,
and finishing at higher accuracies in changes of the speed. Additional support in manner of hall
sensors and index mark allows us to create devices where we are mostly interested in high accuracy
and precision for example in space technology or military. The confirmation of all above can be
found in Mars Robots Spirit and Opportunity - which also base on Brushless Motors.
Another device which allows me to get new experience was H8S/2638 microcontroller. My final
opinion about it is also very positive. Although the calculation power of it is comparable with
t at the same time some futures like: PWM Timer, TPU,
Watchdog, support for CAN, high number of I/O ports, exception handlings and many others make
this microcontroller very useful for control of Brushless Motors (and not only brushless). Of curse
there are also some drawbacks. First is a lack of some software simulator of it. If there would exist
some similar tool like AVR Studio for ATmega128 microcontroller, the speed of creating and testing
programs for H8S/2638 would highly increase. Second, there is missing FPU (floating point unit). This
can lead to a situation, when we need some external computer to make more complicated
calculation. For example, it is almost impossible to use only H8S/2638 for full autonomous
odometry.
Finally, here are a couple of words about PXMC library. Now, after several hours spending on
working on it, I really like it. PXMC has a strong potential to become one of the best library for
motor control. The one big problem is a lack of a good and actual documentation. Because of that,
for the beginners, going through and analyzing the code is like trip through the jungle (hopefully
there are some guiders ;)). Except this drawback, there are a plenty of positive aspects. I will present
only couple of them. Firstly, if someone has some experience with it, it is really very easy for him to
extend the library and add support for new devices. Secondly, the concept of BSP (Board Support
Package) brings high simplification of the use of code for supported boards and motors. Thirdly,
because PXMC is written in C, it is very easy to increase its performance and speed by adding some
assembler parts. Finally, because this library is under GPL license, everyone can use it for free even
for commercial purposes. One thing worth to note is a need of simulator. As far as I spoke with
Michal Sojka, there is a plan to create some simulator of PXMC. Personally, I think that now it should
be one of the priorities for PXMC. Having such simulator would allow to spread this code among
different users than students. This potentially new programmer and developers probably, even