Rolls Royce Case Study - Fatigue Test System

Rolls Royce commissioned TBG Solutions to modernise four independent fatigue machines. A single user interface was required to setup and operate each of the four machines simultaneously.


System Design

National Instruments cRIO hardware comprising of a Real-Time controller (cRIO-9004), an analogue input module (cRIO 9215), four digital input modules (cRIO-9401), a digital output module (cRIO-9476) and a high speed digital output module (NI 9474) are combined to control the 4 machines. Each fatigue machine uses a Parkers Compax3 motor system to drive a linear actuator.


Using National Instruments cRIO technology allowed both the FPGA and Real-Time environments to be utilised in a single control system. The FPGA was used to achieve high speed data acquisition and autonomous PID control of each machine. The Real-Time environment was used to analyse the data and generate the test setup via the user interface. Since each test is intended to run for several days, the stability and reliability of the system is paramount. To achieve this, the Real-Time environment provides access to the user interface via the web server in addition to providing data logging facilities.

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Design Challenges

The main challenge was to implement high speed data acquisition with PID control for each of the four machines using a three million gate FPGA chip. To achieve this highly optimised PID controls were generated to run the trapezoidal profiles.


The Parkers Compax3 motor control system allows various different methods of control to be utilised. In order to determine which type of control was most suitable for the application each of the methods was trialled. As a result of the trials, frequency modulation control was implemented in the final control system.


System Results

The final system allows for independent control of up to four fatigue test machines from a single user interface. The test setup procedure has been greatly simplified and the ability to load saved test setups ensures that the correct test criteria are used.