As Alex Osborn said: "ideas evaporate faster than water". I think is better fix all the steps and project decisions in a document so it is possible review them in a long time.
Now in the resource gadget on this page you can find a link to that document. Now it is incomplete but I want update it along this project so at the end it can be use for reproduce and fix it .
In order to reach this result driverd
We selected the motor model we have, all parameters are set automatically
Auto phasing was asked, this activated a procedure for sensor phasing.
Position loop is set for minimum following error this is the best for this application.
Autotuning procedure was asked, this activated a strong step movement for loop gain computing. This procedure will ‘be done again when motors will be mounted on the telescope with real mechanical charge.
These are computed control parameters from autotuning procedure
Position sensor parameters are left as default.
This assure the position accuracy 360/4096 = 0.087 °
Hello to all,
work is in progress on the controller side.
We select Raspberry Pi 4 Model B as controller for the observatory. It is a medium performance controller and low prices, has a Linux operating system and is supported by Codesys. Many hardware peripherals are available on the market for Raspberry. CODESYS is the leading manufacturer-independent IEC 61131-3 automation software for engineering control systems. This provides us Ethercat fieldbus support, sophisticated motion libraries and communication libraries over IP. It is used for the brushless driving with DS402 profile.
Wifi connection is use for the communication with PC where Polypus is
installed. Morover Raspberry has many GPIO lines useful for digital I/O
connection and I2C line where many more complex devices can be manged.
For Raspberry OS installation the Raspberry Pi imager is used. It can be download from the official Raspberry website, it allows the OS selection. We used the raccomanded
With this step the SD card is programmed ready to be inserted in the Raspberry board.
After that connecting Raspberry to: a video monitor, a USB keyboard and a USB
mouse we have our own system running.
Other steps needs to be done in order to complete installation:
Now you have Raspberry with standard linux support. For application where the
real time is important jiitter genarate by task context switch need to be
reduced. For this porpose a stronger kernel have to be installed. It can be
found at following address with the info for installation.
https://www.raspberrypi.org/forums/viewtopic.php?t=250927
On this Linux system we install the Codesys runtime for Raspberry. First step is the Codesys developing system (IDE) on a PC. Main purpose of this software is the application developping. It can be dowloaded for free with this link:
https://store.codesys.com/tag/product/list/tagId/38/
After download ad installation we have the environment running
For Raspberry runtime installation and programming an extra package need
to be get from Codesys website from this address
https://store.codesys.com/codesys-control-for-raspberry-pi-sl.html
This package is not for free but without license it is possible use it in demo mode for 30 minutes after that it is automatically stopped. This is enough for developping and evaluation.
Package needs to be installed in the codesys with menu command:
tools/Package manager.
After package installation with the command: tools/ Update Raspberry Pi
we have this panel. Selecting Raspberry IP address, giving the password for pi
user you set in the OS installation and pressing “Install” button you have
codesys runtime on our own device.
A friend of mine, owner of a company that uses a lot of motors, was very kind and gave me two high performance bruschless motors. With this motors we intend to drive the right ascension and declination of the telescope.
The motors are equipped with a resolver that allows to control the motor position to less than a tenth of a degree.
Then we purchased two Infranor servo drives capable of driving these motors through the Ethercat fieldbus with DS402 profile.
Now we need the controller for the initial tests.
Hello everyone, the Bassano Bresciano observatory (code 565) has been fully automated and remote controlled for some time. It can work automatically all night without the presence of operators and can be remotely controlled. Now the growing needs require a rethinking of all parts of automation. We open this blog with the intention of publishing all the steps that we will perform in this modernization operation allowing anyone to access projects and software in the hope that they will be useful.
