Controlling Multistability in Vibro-Impact Systems: Theory and Experiment

UK has been one of the industrial powerhouses of Europe from the time of the Industrial Revolution onwards. Today, it is a major challenge for power intensive industries in the UK to optimize their energy strategy in order to ensure long-term sustainable economic growth. Strategies for engineering systems to improve their energy efficiency are to become vital. This project intends to unravel a practical question: can we improve the energy efficiency of engineering systems through judiciously switching between their coexisting states? The proposed research aims to develop a novel control strategy for multistable engineering systems in order to maintain their performance within a satisfactory level by implementing an energy-optimal steering. This will be achieved by studying a novel non-smooth dynamical system, namely the vibro-impact capsule system through both theoretical development and experimental validation. For the first time, the project aims to use the system's basins of attraction (BoA) for control purpose, and seeks the minimum energy solution by exploiting the positive attributes of multistability. In the long term, this project will be fundamental for the realization of energy efficient control, which will provide safe, reliable, and efficient operations for future engineering systems. The approach to realize this ambitious goal in a 21 month project is: (i) to study multistability in the vibro-impact capsule system and its BoA numerically and experimentally; (ii) to develop a new control strategy for switching between different coexisting attractors; and (iii) to verify the proposed control strategy experimentally using the experimental rig of the capsule system.

The proposed practicable control strategy for controlling multistability will be fundamental for the realization of energy efficient control, which will provide safe, reliable, and efficient operations for future engineering systems impacting on almost every industrial sector, from energy saving systems (e.g. energy harvesting) and rotary machinery (e.g. jet engine) to small consumer devices (e.g. hard disk). Therefore, this research project will have a significant impact on the economy, as well as society, as both industrial companies and individual consumers will be the ultimate beneficiaries of such advanced technology.

Vibro-impact engineering systems, such as milling machines, rotary engines, and moling rigs, require large amounts of power produced through the use of fossil fuels (i.e. coal, oil, and natural gas), and any undesired vibrations and impacts may cause these machineries to become inefficient. According to the Energy Consumption in the UK (2016), in 2015, the energy consumption of road transport increased by 1.4% from 2014, to 40,521 ktoe, and the energy consumption of air transport increased by 1.2%, to 12,573 ktoe. At the global scale, the utilization of fossil fuels is still dominant supplying about 85.9% of the world's energy in 2015, and the demand for fossil fuels is increasing. The consequences of the combustion of fossil fuels for power production are serious threats to the environment, causing global warming and climate change. According to the BP Statistical Review (2016), global CO2 emissions from energy consumption grew by 0.1% in 2015. Thus, for power intensive industries in the UK, this scenario strongly motivates the need for energy efficiency. In the long term, this proposal serves exactly this aim, by developing energy saving control technology for a broad range of industrial applications. For example, the energy sector has a significant effect on the UK in terms of its impact on the economy. It aims to maximise the economic production of the UK's offshore oil and gas resources in future decades by enabling industry to better understand complex reservoirs, reducing exploration costs, and improving offshore efficiency. The control strategy developed in this project will contribute directly, revolutionizing current drilling technologies, and ultimately enabling more efficient drilling through saving operational time and reducing drilling costs.

One of the outputs of this project, the development of a novel experimental test bed, will be of fundamental importance to the development of future inspection devices. Experimental investigation of the novel capsule system in this project will provide theoretical basis and proof-of-conception demonstration for developing the capsule prototype for medical diagnosis and engineering pipeline inspection. The direct impact will be on the robotics research groups working on minimally invasive surgery, smart sensor network, and engineering pipeline inspection. Consequently, success in this project will open doors for new collaborations in wider research fields.

Thus, the pathways to impact can be summarized as:
- Publications in high quality journals of international readership, and presentation of results in prestigious international conferences;
- Presenting results in industrial conference, and directly interacting with industrial researchers to maximize their awareness of such advanced technology;
- Organization of an international symposium to bring together specialists in the relevant fields so that the research outcome generates direct impact on these beneficiaries;
- Training a postdoctoral research associate and two PhD students in the emerging field of nonlinear dynamics and control;
- Maximizing public awareness of the societal benefits of the research via project website and social media.