High integrity actuation system with embedded intelligence

(TSB Technology Programme Grant, 04/2007-09/2010. PI – Professor T X Mei, in collaboration with Intelligent Motion Control, Stored Energy Technology and Total Motion Systems)

The provision of actuation in safety critical control systems normally demands a high level of hardware redundancies with the use of multiple actuators, sensors and electronics in order to meet the strict system integrity requirement. The actuators tend to be far more expensive in control systems than the sensors and electronics and are more difficult to tackle with conventional analytical redundant approaches. In many cases, the prospect of the much increased cost often delays or even prohibits practical applications of advanced technologies which would otherwise provide much needed performance gains, efficiency improvement and other savings.

The key research of this project is to develop a practical solution that will provide the necessary control actions (i.e. actuation) and in the mean time satisfy the expected safety and reliability requirements, but minimize the use of hardware redundancies to reduce the component count in the use of actuators and associated controls. The project aims to meet the difficult challenges through the intelligent exploitation of the inherent properties of electric actuators and integrated FDI and control methods.
The Principle Investigator at Salford University was the initiator of the project and has provided the original ideas which the project is based on. The University of Salford is the only academic partner, responsible for driving the technology and for providing critical research input.

The project is funded by TSB (Technology Strategy Board, UK) through their Technology Programme Grant and supported by industrial partners.

Principle of steer-by-wire

Fault Tolerant Actuator Test-Rig

Novel integrated control for vehicle traction and steering systems

(TSB KTP Grant, 11/2007-11/2010. PI – Professor T X Mei, in collaboration with GGS Engineering)

The increased awareness for the need for low carbon based transport has helped to accelerate the development of both public transport vehicles and personal cars. It is expected that the next generation of the vehicles must not only be energy efficient and produce less (direct and indirect) pollution, but also improve their attractiveness to the public through for example enhanced performance, safety, comfort and ease of use etc.

This project is in collaboration with GGS Engineering in Derby to develop a high performance and ultra efficient control system for the integrated provision of traction and steering with the use of in-wheel electric motors, i.e. motors built into wheels. The use of the wheel motors offers advantages of mechanical simplicity and power loss reduction, but this study also seeks to control the electric motors on the two sides of a vehicle independently for the provision of vehicle steering/guidance in a new form of steer-by-wire. The technology developed in this project will be suitable for applications in both railway and automotive industries.

This project is jointly funded by TSB (Technology Strategy Board, UK) through the Knowledge Transfer Partnership Scheme and the industrial partner GGS Engineering.

Test Vehicle

System-on-chip approach for real time simulation, PhD project, 2006-10

Supervisor – Professor T X Mei

The implementation of complex control laws or computationally demanding simulation algorithms for real-time applications often requires the use of high performance processors and sometimes complex multi-processor architectures. In particular, hardware-in-the-loop approaches are now becoming increasingly popular in the development of control solutions for large and complex systems where full scale testing can be time consuming and/or expensive to carry out.

This innovative project is concerned with the development of a system-on-chip based accelerator for the real time simulation of complex and computationally intensive mathematical models. The main aim is to enable real time control implementation/testing in a hardware-in-loop environment, but it can also be used to speed up computer simulations in the study and design of complex systems. The design of a multi-core accelerator with six CPUs and two sets of floating point units is implemented on a single medium sized and low cost FPGA (field programmable gate arrays) device and is shown to deliver a far superior computation performance than high performance DSPs or the latest PCs.

The project is funded by UK ORS Award and Tetley & Lipton award

Control of asymmetries in permanent magnet electrical machines

PhD project, 2006-10. Supervisor – Professor T X Mei

It is usually assumed that manufactured 3-phase rotary machines have symmetrical windings. However, because of tolerances in the manufacturing process, the asymmetries between phases may occur. The causes of phase asymmetries can be of mechanical or electromagnetic nature. Furthermore, linear machines with more than 2 phases have inherent asymmetries of phases, which are associated with increased reluctances of the flux paths at the ends of magnetic core.

The dynamic analysis of 3-phase machines is usually carried out using the d-q model which assumes that the machine parameters (inductances) of different phases are symmetrical and almost all latest control systems are developed based on the assumption which can lead to significant torque ripples in the machines with substantial asymmetry properties.

The main objectives of the project include: to develop appropriate modelling methods that take into account of the asymmetries in the electrical machines; to emulate the asymmetrical conditions with a standard permanent magnet motor to ‘re-create’ the torque ripples with the conventional control method; and to develop practical solutions for improved control performance.