Fab Lab Frosinone

Testing Steppers and Coordinates:

From a software point of view, if you want to create new machine, you have to import the Gestalt library.

-From pygestalt import:
1) Nodes
2) Interfaces
3) Machines
4) Functions

-From pygestalt.machines import:
1) Elements
2) Kinematics
3) State

-From pygestalt.utilities import: notice
-From pygestalt.publish import: rpc #remote procedure call dispatcher
-Import time
-Import io

Next you define the virtual machine class that is a set of functions and parameters that defines the machine (i.e. number of axis, kinematics etc), class virtualMachine(machines.virtualMachine).
Then you tell to gestalt how to connect with the nodes.
Here is important to change the name of the serial port used:
-def initInterfaces(self): if self.providedInterface: self.fabnet = self.providedInterface #providedInterface is defined in the virtualMachine class.
else: self.fabnet = interfaces.gestaltInterface('FABNET', interfaces.serialInterface(baudRate = 115200, interfaceType = 'ftdi', portName = '/dev/tty.usbserial-FTXW9L60'))

A very important part is the definition of the axis. Here you can define how many axis will have your machine. In the definition there is also the python file that describes the virtual node class, with important parameters and routines of the nodes. We have 4 nodes of the same type but you can have different type of nodes together.
The last line defines the compound nodes. It is useful as you can treat the nodes as one. Sending a command to a compound node affects all the nodes that are listed in it.

In our case we have two axis (z and k) that make the same moves def initControllers(self):
-self.xAxisNode = nodes.networkedGestaltNode('X Axis', self.fabnet, filename = '086-005a.py', persistence = self.persistence)
-self.yAxisNode = nodes.networkedGestaltNode('Y Axis', self.fabnet, filename = '086-005a.py', persistence = self.persistence)
-self.zAxisNode = nodes.networkedGestaltNode('Z Axis', self.fabnet, filename = '086-005a.py', persistence = self.persistence)
-self.kAxisNode = nodes.networkedGestaltNode('Z Axis', self.fabnet, filename = '086-005a.py', persistence = self.persistence)
-self.xyzkNode = nodes.compoundNode(self.xAxisNode, self.yAxisNode, self.zAxisNode,self.zAxisNode,self.kAxisNode)
-self.zkNode = nodes.compoundNode(self.xAxisNode, selfkAxisNode)

Another important point is where you can set the kinematics properties of the nodes.
They depends on the physical characteristics of the nodes used (step, microstep, pulleys etc).
It is very important to correctly set up the parameters or it will result in an incorrect movement of the node especially regarding the correspondence between the machine coordinates and real world coordinates.

def initKinematics(self):
-self.xAxis = elements.elementChain.forward([elements.microstep.forward(4), elements.stepper.forward(0.9), elements.pulley.forward(11.6), elements.invert.forward(True)])
-self.yAxis = elements.elementChain.forward([elements.microstep.forward(4), elements.stepper.forward(0.9), elements.pulley.forward(11.6), elements.invert.forward(True)])
-self.zAxis = elements.elementChain.forward([elements.microstep.forward(4), elements.stepper.forward(0.9), elements.pulley.forward(11.6), elements.invert.forward(True)])
-self.kAxis = elements.elementChain.forward([elements.microstep.forward(4), elements.stepper.forward(0.9), elements.pulley.forward(11.6), elements.invert.forward(True)])
-self.stageKinematics = kinematics.direct(4) #direct drive on all four axes

Then you can initialize the functions for moving the machine. You can see the corresponding class in the functions.py file. Here we initialize the map and the job command. As we have a compound node (z and k) we set it as the third argument that will be sent to the machine.

When you create an instance of the machine with this line
instancename = virtualMachine(persistenceFile = “filename.vmp")
you create a “persistence file” that stores the machine configuration.
Indeed when you first run your code the nodes will start flashing and a message will ask you to identify the axis.
You have to press a button on the the gestalt board to tell to the system the correct axis sequence. If you want to reconfigure that you just have to delete the .vmp file.

Then you can choose the way you want to control the machine. You can include the virtual machine into a python program, you can put the commands directly into the code or you can use the RPC to remotely call the functions of the gestalt.
We used the last one.
You can expose functions with this command:
-rpcDispatch.addFunctions(('move',desktopFactory.move),
('position', virtualmachine.getPosition),
('jog', virtualmachine.jog),
('disableMotors', virtualmachine.xyzkNode.disableMotorsRequest),
('loadRemote', fileReader.loadFromURL),
('loadLocal', fileReader.loadFromFile),
('runFile', fileReader.runFile),
('setPosition', virtualmachine.setPosition))

As we didn’t find a complete documentation to better understand how to call the remote procedures we analyzed the calls made by the following site:
'http://tq.mit.edu.'.

We created a command to load a local files or a remote file containing a path that the machine will follow.
Inside the file we put commands that are mapped into another RPC function:

fileReader.addFunctions(('move',virtualmachine.move), ('jog', virtualmachine.jog))

Indeed reading from a file is better than send commands from a website as HTTP protocol is stateless and there is a risk of a delay due to network issues.

Here you can see the code to make a simple square:
/move?position=[None,None,-2,-2]&velocity=1
/move?position=[None,80,None,None]&velocity=1
/move?position=[80,None,None,None]&velocity=1
/move?position=[None,0,None,None]&velocity=1
/move?position=[0,None,None,None]&velocity=1
/move?position=[None,None,10,10]&velocity=1

---

WEB INTERFACE:

We made a first interface prototype visible at
'http://www.my-id.org/utilities/test_interface_5.html'
that sends commands to the machine using ajax calls.

We planned the following workflow:
- jog the machine to reach an home position
- set the home position (set position 0 on every axis)
- load a file
- run the file


After we made a second interface always using html5.
You can target the function you need by a browser, addressing to 'http://127.0.0.1:27272/'

The commands we use are:
/setPosition?position=[0,0,0] set the actual position as zero.
/move?position=[x,y,z]&velocity=v the 3 values are the coordinates that each axis reaches. “none” doesn’t move it. “v” is the speed machine value.
/jog?incrementalPosition=[x,y,z] the 3 values are the numbers of step that each axis jogs. no velocity needed. negative numbers to reverse direction.
/disableMotors to stop the machine immediately and disable the motors.
/runfile? to run the uploaded file.