qbmove simulink library

Installation:

Downloads

To be able to correctly use these libraries, you will need to download the current APIs You can find them here. You will need to just download the qbAPI folder and save it side by side with the qbmove_simulink folder. Before compiling be sure to have a folder tree like that (be sure to remove the -master suffix):

• working_directory
  • qbAPI
  • qbmove_simuilnk

NOTE: if it is the first time you use the qbmove units on your computer, it is possible that you need to download the drivers to let your computer see the port correctly. To do that visit FTDI driver webpage -> VCP drivers and download the proper driver depending on your OS

The compiler

1. First of all be sure to have a C compiler installed in your system. Execute the command "mex -setup" on your Matlab Command Window to let Matlab use your compiler. The suggested is the "MinGW64 Compiler".

2. If you don't have any, install the "MATLAB Support for MinGW-w64 C/C++/Fortran Compiler" either through the add-on page or following this link.

   If you have trouble in this step, try follow this link.

Compile and Include the library

The library can be used on various operating systems such as MacOS X, Windows, Linux... but you need to recompile it for your system.

1. Move your position in qbmove_simulink folder,type install and press return. It will install the library depending on your MATLAB configuration and set necessary path. If no error is returned the libraries are correctly compiled and it is displayed a successful comment on shell.

Use

Create a new simulink model

1. Click on the "Simulink Library" icon or type "simulink" in the Matlab Command Window.

2. Create a new model using: "File -> New -> Model"

3. In the new model go to: "Simulation -> Model Configuration Parameters". Under "Solver" select as Type "Fixed-Step", as Solver "ode1 (Euler)" or "discrete (no continuous states)" and as Fixed-step size type the delta_t in seconds. (e.g. if you want to retrieve positions and set new inputs every 5 milliseconds, type 0.005). Click "OK".

   Every qbvmove needs at least 1 millisecond to read and set new positions, so the minimum step time allowed is 1 millisecond multiplied by the number of qbmoves in the chain.

4. You should be able to see "QB Pacer" and "Qb Move Library" under libraries in Simulink Library Browser. From here drag and drop the desired blocks onto your model.

The main blocks

• QB Pacer You need one of this block to be in your model, otherwise the simulation time will not match the real time. You can set a number representing the simulation time real time ratio. Leave it set to 1 for normal use.

• QB Move

  This block is the interface between your computer and the real qbmove. By default you will see 3 input ports and 4 outputs ports. This means that the block is set to both receive information from the sensors and send new position reference and stiffness to the qbmove. If you double-click to the block, the Function Block Parameters will open and you will be able to set the proper ID for your qbmove and the Communication Direction. If you set Tx, you will be able to only send new reference input to the qbmove. If you set Rx you will be able to only read the the position sensors value. Either the inputs and the outputs are in degrees.

  To use this block you MUST have a "QB Move Init" block connected to the first input handle.

  To use multiple qbmoves, just put an array containing the IDs in the ID field and use a mux to send multiple inputs to the eq. pos and s. preset ports.

  ID 0 is broadcast ID so if you want to move a qbmove you do not know the current ID, just use 0

• QB Move Init

  This block is used to provide the right handle to the other blocks and allows the communication between the computer and the qbmoves.

  • WINDOWS

    Under windows the qbmoves are seen as Communication Ports (COM1, COM2, COM#...).

    If your qbmove is not automatically recognized by windows, try to manually install the FTDI drivers from here

    You need to modify the port number to allow simulink using it. Click on START and type Device Manager. Go under Ports (COM & LPT), right-click on the COM# associated with your qbmove and open Properties. Select the tab Port Settings and click on Advanced.... Be sure to set a port number within 1, 2, 3 or 4. Click OK and OK again. Now you can come back to your simulink model, double-click on the QB Move Init block and type the port you choose between single quote mark (e.g. 'COM1').

  • UNIX or MAC

    Under unix you do not need to make any special modification to your port.

    If you use MacOSX, you probably will need to install the FTDI driver following this link.

    To retrieve the name of the port you need to open a Terminal window and type ls /dev/ You should see a series of interfaces:

    • MAC OS X: the interface is usually called "tty.usbserial-XX" where XX is the serial of the qbmove.
    • LINUX: the interface is usually called "tty.USB0" or similar

    Now you can come back to your simulink model, double-click on the QB Move Init block and type the port name between single quote e.g. '/dev/tty.usbserial-13' or '/dev/tty.USB0'

Example:

In the "examples" folder you will find an example called "qbmove_basic_example.slx" This is a simple configuration which you can use to test your qbmove. On the left there are two slider gain which can be tweaked while the simulation is running and you can see the result on the qbmove. On the right there are 3 displays where you can read the values in degree of the 3 sensors (1 and 2 are the motor shafts, 3 is the qbmove output shaft). The output error can be used to see if there are errors in communication. It starts from zero and it is incremented by 1 every time a communication error occurs. As you can see in the bottom-left corner there is also the "QB Pacer" block used to ensure the correct synchronization between simulation and real time. If you want, you can use the output of this block to trace the time of the simulation.

If you take a look at the scope you can observe two lines. One is the simulation clock and the other one is the real time pacer output. If they overlap, the sample time of the simulation is properly chosen, this means that the step size is big enough to let the communication finish between two consecutive steps. If the two lines diverge, you have to use a bigger step size.

In this particular configuration, the step size is set to 2 milliseconds and the computer should be able to run it in real time. This means that every 2 milliseconds you send a new reference position to the qbmove and the current position is read. Furthermore a current reading is done and you can see the milliampere absorbed by each of the two motors.