3 linear actuators and 1 semi rotary actuator position Control-all analogue

[Martin.OlearyCIT]

Hi,

I am using a PCI-7344 with a UMI-7764 to try and control 3 linear actuators and 1 semi-rotary actuator, each of these actuators takes a 0-10v dc voltage and has a feedback signal of 0-10v dc, both input and output being proportional to linear/angular displacement.

Im not very advanced with LabVIEW and I assumed that it would be relatively simple to take in a signal somewhere between 0 and 10v and "operate" on that signal to determine the outputs to the other 3 actuators. By operate I mean to perform basic mathematical functions on a the proportional number between 0 and 10 (feedback voltage).
Basically take in a 0-10v dc signal and based on that value send out signals of between 0-10v to 3 other outputs of the umi-7764
 
Ive been sifting through all the NI-Motion vi's but cannot seem to find what im looking for.
Im sure that there is a simpler way of doing this but I can't seem to figure it out.

Please help as this is a rather simple problem(i assume) which is stopping project progress.

Thanks.

[Highland_Controls]

I'm not sure what your motion controller would be doing in this situation.  It appears that you already have a position controller that takes in a 0-10VDC signal to position the actuator.  Is the feedback just for information, or is it supposed to be used to alter the control signal.  Please give us more information on your hardware.

[Martin.OlearyCIT]

Ok I am basically controlling a manipulator which is to be actuated with pneumatic actuators(3 linear and one semi rotary), the actuators are capable of giving a proportional 0-10v dc feedback, and are actuated by a 0-10v dc signal.

The method of controlling the actuators will be a 5/3 proportional servo-valve, which will receive a 0-10v dc signal. If the valve is receiving 0v then the actuator will stay "home", when it receives 10v it i will be fully extended and any voltage in between will position the actuator proportionally along its stroke.

Firstly, there are two actuators which need to be master and slave, (the equivelant, in my mind, to a mechanical link). The first actuator fully extends and as this happens another actuator which starts fully extended goes home, but this second actuator's position must be controlled by the first actuator (Feedback).

This sequence is to be repeated every time before the next sequence, and goes in reverse after the second sequence (returns home),

The next sequence involves another linear actuator and a semi-rotary actuator (270degree).

This part of the sequence will involve a combination of linear position control of the linear and angular position of the rotary, but the roatary is controlled by the exact same method as the linear so the fact that it is rotary is irrelevant.

I will be given x,y,z coordinates (4) to reach but the linear rotary combo will only involve a 2D problem. So i will do some maths in a vi I made to determine, depending on the x,y coordinates, what voltage between 0-10 I must send to the linear and rotary actuators in the end effector. Hopefully the attached pdf's can help visualise the problem.

Just to be clear I want to use the pci-7344/umi-7764 combo to send the 0-10v signals to control the valves and to take in the 0-10v feedback signals from the encoders.  The main reason I want the feedback signals is to close the loop. I may want to manipulate the signals in labVIEW but all I want to do now is send out 0-10v signals to 4 servo-valves and receive 4 0-10v feedback signals.

Maybe the pci card is overkill, I don't know, i'm sure I could use a general breakout box type system but the setup I have is all we have in my lab.

[Highland_Controls]

Please give information on the position controllers you are using.

[Martin.OlearyCIT]

Hi

I am using the PCI-7344 motion control card, nothing else.

[Highland_Controls]

You stated that you have something that is controlling your actuators.  What is doing that?  I am not referring to the mechanics or the PCI card, but there is something that takes 0-10VDC and puts out 0-10VDC.  What is that?

[Martin.OlearyCIT]

Sorry I misunderstood,

In the field there will be a controller provided to do this, an SPC200 4 axis controller, It will have programmes downloaded to it and can run independant of a PC BUT I dont have this now and my Festo contact assured me I could run the system without this through labVIEW for prototyping.

What I want to output the 0-10V DC to is a servo valve, so depending on what voltage this gets the servo will control the position of the valve and hence the actuator. The feedback is by way of a sin/cos encoder built into the actuator, this encoder signal is then passed through a transducer which will convert the signal to a DC voltage. 

I don't have anything other than the NI hardware and this mechanical hardware.

I have included the documentation for the 3 pieces of hardware; actuator+encoder DNCI, servo operated valve MPYE and transducer DADE (Included in the DNCI pdf).

I may be wrong but I am assuming that the PCI/UMI combo can output the voltage to the servo and can take in the voltage from the transducer.

[Highland_Controls]

The servo valve position has little to do with the actuator position.  The servo valve is controlling air flow and direction, and will essentially push your actuator in one direction or the other, with a certain amount of speed/force.  The valve is somewhat unusual in that a signal of 0V will output full flow in one direction.  This can be dangerous, particularly at startup.  You should contact NI tech support on how to setup the 7344 in this situation.

[Martin.OlearyCIT]

Yes but the valve is a proportional 5/3 not just a 5/2, there is midstroke positioning by regulating air between two input ports of the actuator, so where the servo is positioned determines the proportion of air between the two input ports of the actuator and hence the position.

When there is 0V going to the valve all airflow will be to one port, this is designed to keep the arm in the home position when not in use. I.e. the 0V to the valve case is always the initial position.

Thanks for your suggestion.

[Highland_Controls]

The valve position to actuator position is analogous to electric motor position and current.  Open loop current cannot position a motor, and valve position is not proportional to actuator position.  The 7344 is needed to modulate the valve and control position.  The valve position required will vary based on acceleration, velocity, load, etc.