A servo controllerfor an MTS machine

Characterization Presentation

David Schwartz & Uri goldfeld

Supervisors :

Dany Alkalay & Mony Orbach

Project Goal:

Implementing a new control system for the MTS machine Located at the Material Mechanics Laboratory.

Replacing the current controller with the noval one .

Currently we have the old system with a built in controller:

We will replace the old controller using LabView:

FPGA LabView

We configure an FPGA NI board using LabView to replace the old controller

Material Testing Machine (MTS)

General Description:

Purpose – finding the strength of

various materials Under static

and dynamic loads.

The machine does

Tensile or compression static tests

And fatigue testing under cyclic

dynamic loads .

Force is applied using a servo valve

Actuator

Stress vs Strain

The control loop

PID controller MTS+-

Command

LVDT

The machine is controlled in a closed loop.The control loop is modeled as an SISO LTI system.

Load cell1

2

Force = 1Displacement=2

CommandsTwo action modes:

1.Force – usually used in static experiments.The feedback

is through the LoadCell sensor which converts Force

applied by the servo valve to voltage.

2.Displacement – usually used in dynamic experiments.

The feedback is through the LVDT sensor which converts

the position of the servo valve to voltage.

Controller necessity

The machine’s input has to abide to certain limitations.

Illegal input may be destructive.

For Example :

giving the servo valve too much acceleration will produce force that might break the machine.

The controller has to pass through only legal commands,

He will do it using an FSM that checks for irregularity

In the given commands.

Tools and Techniques Development environment:

SoftwareLabView 7.1 software and toolboxes:Control system and simulation toolbox.State machine development toolbox.FPGA module and real-time capabilities.Hardware

The MTS systemMultifunction DAQ board.

NI FPGA board NI PXI-7831R

Datesassignments

On goingLearning LabView development environment and tools.

Two weeksFinding the servo valves transfer function H(s)=a(s)/b(s) using system identification techniques.

One week”Reverse engineering” of the current MTS implementation.

Two weeksDefining systems nominal requirements and limitations.

One weekDesign a basic MTS servo system simulation in LabView.

One weekpreliminary specifications of the experiment protocol GUI.

Project Schedule