control your Cartman Cartesian robot via a serial port on your computer from python.

git clone https://github.com/ctmakro/cartman
pip install -e cartman # "-e" means "edit mode"

cd cartman
git pull

from cartman import bot

b = bot()
b.home()
b.set_speed(1000)
b.goto(x=10,y=10)
b.sync()

Make sure you've read the Cartman User Manual before trying anything here.

The Cartman robot is connected to your computer via a USB-serial link. When you instantiate the bot class, you will be prompted with a list of available serial ports on your OS. The chosen port will be connected.

you can of course initialize the class with a serial port of your choice (instead of prompting the user) as follows:

b = bot(name='COM2')

The bot object will print out everything it sends and receives via serial. you can suppress the printouts by specifying verbose=False on init:

b = bot(verbose=False)

After connected to the specified serial port, the controller board will likely reset itself, so we have to wait until the bot is ready to receive commands. The library will repeatedly send $X command to the bot and wait for an ok response. The call will block when waiting for an ok response.

The initializer will return after the expected ok arrives. You can now send more commands to the bot.

b.command_ok('G1 X100 Y100')

The call above sends the command G1 X100 Y100 to the bot and returns after receiving an ok response.

b.send(c) is shorthand for b.command_ok(c).

• Instead of constructing/sending commands yourself, we suggest using methods listed below for normal operation of the bot.

b.home() is shorthand for b.command_ok('$H'). As stated in the User Manual, the bot won't do anything before homing.

b.goto(x=100, y=20, z=-5, f=1000) is shorthand for the command G1X100Y20Z-5F1000.

b.set_speed(1000) is shorthand for the command G1F1000. The bot will not move before a speed is specified.

b.set_offset(x, y, z) will shift the coordinate positions specified in later b.goto() calls by x, y and z correspondingly.

b.init_offset() is shorthand for b.set_offset(0,0,0).

b.sync(), b.join() and b.wait_until_idle() are shorthands for "wait until the bot got into its 'Idle' state". Three methods are identical.

When you send a movement command to the bot, the call usually returns before the command is executed. The command will be stored in a buffer within the controller board, which enables the bot to lookahead and plan the motions with appropriate speed transitions.

So if you send a bunch of commands to the bot, then immediately quit the python script, the serial port will be closed before the bot finishes all the movement. Unfortunately this particular controller board will reset itself when a host disconnects, which will cause the bot to stop before all buffered commands are executed.

The solution is to call b.sync() at the end of your script, which will only return after all buffered commands are executed.

b.where() returns a list of 3 floating point numbers, in case you want to know the working position of the bot in real time. Do not call this function too frequently as it pulls data from the controller board via serial on each call.