alter() usage

    I'm developing a program without a simulator/robot at the moment (still waiting for some people to get their act together and get me the robot!), and one of the functions I need to use is the alter() function. I'm a bit unsure about the structure of it as there's limited information in the documentation, could someone tell me if I'm doing things in the right places?

    In an async. function, I have:

    Code
    taskCreateSync "controller", dt, b_overrun, controller()

  // Start the alter() process.
  wait(alterBegin(t_flayer, m_sequence))

  alterMovel(appro(here(t_flayer, world), tr_sequence), t_flayer, m_sequence)

  // End the alter process.
  wait (alterEnd() == 1)

    And in controller():

    Code
    // Some code to process an analogue signal.
// Some code to compute the transformation required.


alter(tr_offset)


// More tidy up

    Does that look about right? The part I'm not sure about are the alterBegin() and alterEnd() functions.

    Many thanks in advance.

    Hello,

    Some general informations about Alter :

    VAL 3 alter runtime license

    What is the alter runtime license?


    The alter runtime license allows to modify in real time the nominal path of the arm, to adapt it to a changing context such as conveyor position or tool wear out. It can also be used to replace the usual VAL3 motion control with a customer-specific motion control.

    Operation
    To be alterable, the path must be programmed with the specific alterMovej, alterMovel or alterMovec instructions. The alteration is specified as a transformation (rotation and/or translation) that can be modified every 4ms.
    Two alter modes are supported: one allows to define the alter transformation relatively to the arm base (World or any other frame in World); the other allows to define the alter transformation relatively to the arm extremity (flange or any other tool on flange).

    Limitations
    The correct use of the alter instruction is difficult when the alter deviation is changing quickly: sensor filtering, synchronisation and desynchronization algorithms are then required to keep a good control on the arm position and velocity, without discontinuity or noise.

    Some technical limitations are described in the VAL 3 reference manual.

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