Modelling and HIL Testing: We use Dymola modelling and simulation software as an integral part of the design process to achieve the following key benefits:
- Design & development leadtimes minimised by being able to model and simulate designs using multiple domains and systems.
-Early identification of potential problems and design solutions prior to rig manufacture and commissioning, substantially reducing complexity and risk.
-The ability to carry-out rig verification prior to delivery and commissioning.
-On-site commissioning time reduced compared to conventional methods.
-Together, these benefits combine to enable the shortest possible leadtimes from initial requirement through to full rig implementation and operation.
With over 30 years' experience of supplying test rig control systems to the aerospace industry, in both civil and defence project sectors, we have developed a particular understanding of the needs of our aerospace customers.
This enables us to supply customised control systems which not only meet stringent technical and operational requirements, but also offer friendly, efficient and intuitive user interfaces which improve operator productivity.
All aspects of system control are handled, from high-level man-machine interface and machine sequencing to low-level time critical closed loop PID ( Proportional, Integral and Derivative ) control, feed-forward terms for loop optimisation and spike suppression. RTC’s long experience within the aerospace and defence markets ensures that its design and manufacturing methods are optimised to meet the most demanding applications.
Our test rig control systems consist of a “top end” graphical user interface, running in an industrial PC, which controls and commands the operation of one or more “embedded” controllers. These are also industrial PC’s, without screens or keyboards, which run high speed real-time software to perform such tasks as PID control, rig motion control, sequencing and timing, load profiling, alarm monitoring and safety shutdown
RTC has a strong multi-disciplinary team of software engineers, experienced in all aspects of engineering system design. We have extensive experience in ‘C’, National Instruments LabView, Mathworks’ Matlab/Simulink, Dymola and assembler low level programming.
Our graphical user interface is authored using National Instruments’ LabWindows/CVI. The development of this interface over the years has been driven significantly by customer feedback, so is very much tuned to the particular requirements of the industry and offers many features to reduce the operation of even the most complex rigs to simple, intuitive and easily documented operator procedures.
Each control system is unique, the capabilities of our controllers have advanced and continue to advance with available technology. In spite of this, there is a conscious effort to maintain a common “look and feel” to the user interface, so that any requirement for operator re-training on a new rig tends to be limited to issues regarding the new unit under test.
Our control software is written using Matlab/Simulink and implemented on an industrial PC. Using such a platform, running as an “xPC embedded target system”, we currently embed up to four independent control systems, each supporting full non-linear PID control at 1kHz, into a single PC. Concurrent with the PID control, each controller may generate real-time load command profiles, check multiple inputs for alarm limit violations, perform I/O sequencing and supply continuous status information to the user interface via an Ethernet link. Apart from initial set up, embedded PC requires no intervention from the user interface to perform these tasks.
Even with such an apparently heavy workload, the processor still spends up to 70% of its time in idle, so there is plenty of spare capacity for the addition of customised features if required.
Data Acquisition Systems: RTC have developed a fully comprehensive general purpose PC based data acquisition system, authored in-house using National Instrument's LabVIEW. The system employs National Instruments' data acquisition hardware to offer sampling rates of up to 1.25 MHz across 16 analogue channels and has the following features:
Real time on-line (oscilloscope style) display with simultaneous data logging to hard disk. High-speed data logging without display, to achieve maximum sampling rates. Off-line Charting - Plot any channel of recorded data (including time) against any other. Export logged data to Microsoft Excel or compatible spreadsheet.
Waveform generator output - Sine, Square, Sawtooth, Triangle and User defined waveforms.
RTC has over 30 years' experience in single and multi-channel closed loop servo-hydraulic control systems. Typical systems have incorporated closed loop control of position, speed, load, torque and pressure. Profiling of the closed loop gains against control variables is achieved through look up tables in the real time embedded controller.
Profiles are edited and stored on the user interface PC and downloaded to the embedded controller prior to running the test rig. The servo control system is digital, so we are able to vary the PID terms of the controller to cope with extreme cases of static and dynamic operation. Customised algorithms are developed and optimised in the servo controller to eliminate the effect of any non-linearities found in the rig or unit under test.
Our servo control systems interface to the standard range of instrumentation equipment ranging from load cells, torque transducers, pressure transducers, flow meters, tachometers, temperature transducers, rotary and linear position transducers including LVDTs, RVDTs, VRVTs and encoders.
RTC has been involved in many large projects providing control and monitoring of hydraulic ring main systems installed in aircraft hangars and control and monitoring of gas cabinet systems used in the fabrication of semiconductor wafers. These bespoke systems have been designed to the customer’s specification & delivered within very demanding time scales.
All our facility control systems come with the option of comprehensive SCADA monitoring to allow overall plant control and history logging with print facilities. This is often used for energy usage monitoring and preventative maintenance.