motion control for vertical actuator and data acquisition

[GeotechEng]

Hi,


I'm a geotechnical engineering (a branch of civil engineering) researcher, and I have very little knowledge about motion control and data acquistion, so would need alot of help from the NI experts. I have only basic knowledge about these 2 aspects based on my reading of some materials on the NI website and some youtube videos, so I hope you bare with me :). Here are my questions:

I am trying to build an actuator which will be used to push a probe (a penetrometer with a load cell to measure the resistance of a soil sample), which in concept, looks something like the pic in the attached file. I need to have these criterias for my system:

1) Actuator that can push the probe at velocities between 0.01mm/s - 300 mm/s accurately and move the probe cyclically (i.e. upwards and downwards) in the vertical direction 
2) Expected load range on the probe when penetrating into the soil: 0.02kN -  6 kN.
3) need to acquire the load data from the load cell and the velocity of the probe.

4) Able to control the actuator from a PC (velocity and posotion) and monitor the data coming from the tranducers and at the same time log data from the tranducers.

My beginner's guess is i'm gonna need:

For control:
1) Software - LabVIEW and NI-motion assistant

2) Motion controller - NI PCI 7342

3) Driver/Amplifier -  Analog AKD servo Drive

4) Motor - AKM brushless servo motor

For acquistion:
1) software - LabVIEW base development systems

2) Amplifiers or other signal conditioning device - no idea what type

3) Data acqusition device - no idea what type

Since I am a beginner, could someone recommend the components (hardware and software) for both control and data acqusition. I'm on a tight budget, so I appreciate if someone could help me recommend components good enough to build my system.

Thanks for your help.

[Highland_Controls]

Verify your requirements first.  Do you need 300mm/s at 6kN?  If you do, you are going to end up with a big actuator(and big drive, and big power feed, etc.).  Exlar's Tritex will do what you want, but not at those speeds and loads(at the same time).  You can control the Tritex directly from LabVIEW using Modbus/TCP.  Works very well.

[GeotechEng]

Hi Highland_Controls,

Thanks for your reply. I'm expecting large forces at slower velocities, so around 3 - 6 kN at the slowest velocity of 0.01 mm/s As the velocity increases, I'm expecting it to decrease. At 300mm/s, it should be around 0.01-0.1kN.

I've found an actuator that may work: the SKF CASM-63-BF (http://www.skf.com/binary/68-29962/CASM-63---Linear-units.pdf). I wonder if this actuator is compatible with NI products?




Thanks

[Highland_Controls]

That is just an actuator.  You will have to add a motor,a drive, and a motion controller.  NI make neither motors or drives, though they market some.  Really, you should look at the Tritex.  Just give it power and comms, that is all you need.  Everything is built into one unit.

[GeotechEng]

It seems like the Tritex AC linear actuator T2M/X090 fits most of my needs except the stroke length. I don;t see any other Exlar actuators which are fully integrated with driver, motor and motion controller, so I guess the T2M/X090 is my best bet.


How about software? Do I still need NI Motion Assisstant and NI Driver software? For LabView, is the full development system version sufficient?


Thanks a million.

[Highland_Controls]

All the motion is done in the Tritex, so there is no need for any other motion device or NI software.  As will all motion systems, you will have a learning curve.  Not sure how fast you need to read your sensor data.  You may need to have the go to a DAQ card, or it could go to an analog input on the Tritex(after running through a signal conditioner).  I am able to grab a bunch of data from the Tritex reliably at 40Hz via Modbus/TCP.  You only need a LabVIEW Modbus driver(free download).  You will use the Tritex software(free) to setup the Tritex, but all moves can be controlled via LabVIEW.  I developed a ton of Tritex drivers, but they are not publically available.

[GeotechEng]

I guess there is some kind of encoder on the tritex for me to be able to tap data on the displacement (vertical position) of the shaft. Alternatively i could derive the displacement from the velocity or vice versa. I need to log the data at sampling rates of 1/3600 Hz right up to 300 Hz. perhaps I could use the NI Compact DAQ set to log the data from the tritex. I'm gonna need the CompactDAQ anyway for the data from the load cell of the penetrometer

 You mention up to 40 Hz. Any chance I can log at 1/3600  - 300 Hz?

Can I purchase the Tritex labview driver you developed?

[Highland_Controls · Accepted solution]

At those rates you will need to run the sensor to the cDAQ.  You can set up the analog output on the Tritex to scale to position.  There is an adjustable filter that you can set so you can get a pretty clean signal at 300Hz.  When you inquire about the Tritex, be sure you let them know what comms and I/O you want to use.  If I recall, not all options worked together.  The analog output might have to be mA, but you can putting a resistor across the DAQ input to get voltage instead.  I don't remember all the details.  You really won't have to do too much on the Tritex/LabVIEW side.  You will be sending your motion parameters(start position, end position, speed, accel, decel), and whether you are doing one cycle(I think you will) or just running it in a loop.  You also just might be able to use the jog functions.  When you get closer to knowing exaclty what you will need, PM me and I am sure we can work out something with the drivers.  You will only need the basics.  In reality, you could probably do this all your moves via digital and analog I/O.