Hyper-actuated flexure-link structures for high performance bearing-free servo mechanisms

Conventional mechanisms used in robotics and automated machinery have joints with bearing parts that collide, roll and slide against each other. The associated interaction forces have an effect on small-scale motion that limits achievable accuracy when motion is controlled automatically using motors or other forms of actuation. This impacts negatively on the quality and efficiency of various industrial processes, including the assembly and inspection of manufactured products.

If bearings are replaced by compact deformable structures acting as pseudo-joints then small-scale motion behaviour becomes more predictable and precise. Additional advantages are derived from the use of parts that do not rub or wear or require lubrication. A new issue that arises, however, is that flexible joints introduce additional ways in which a mechanism can move and vibrate. These motions must be regulated through suitable actuation and control schemes.

Research is needed on how best to design pseudo-jointed structures to achieve accurate control of motion, not only for precise positioning but also during rapid large-scale configuration changes, without causing unwanted oscillations or instabilities. How to apply actuation forces to a mechanism structure is an important consideration here, but so also is the creation and use of mathematical models to:

1. Design mechanisms for an optimized balance of speed, precision and range of motion.

2. Develop algorithms that will run on a computer to regulate actuation forces and thereby achieve precise control of motion.

This research will find new ways to solve these problems and evaluate their effectiveness by design and experimental assessment of prototypes.

The impact of this project will be wide-ranging and will stem from new engineering approaches to improve speed and functionality of actively controlled mechanisms used for high precision positioning and motion control. Exploitation in manufacturing processes is expected over the short to medium term, but with potential for further application in aerospace and defence systems, space/marine exploration and various imaging, inspection and metrology processes.

In addition to academic beneficiaries (identified separately), the beneficiaries include:

(a) Industry stakeholders: New technology derived from this research will provide opportunities for commercial exploitation by developers and users of machinery for product assembly and micro-manipulation as well as for measurement and inspection processes, potentially extending to microscopy and optical lithography. Benefits will arise through improvements in throughput and quality of outputs in these processes, with knock-on effects for consumers. Commercial advantage and economic gains may also be derived from the creation of new machine designs achieving higher precision and high speeds of operation for given energy consumption than is currently possible.

(b) University employees and students: The research assistant will benefit from new training opportunities and experience of working within a vibrant research-oriented environment. Their project management and organisational skills will be enhanced, as well as interpersonal, communication and dissemination skills. PhD students within the Department of Mechanical Engineering will benefit indirectly through cross-fertilization of ideas. Further opportunities for collaboration and placements with the industrial partner are foreseen. The outputs of the project will lead to educational benefits through their future use in teaching.

(c) Project partner: Molins Technologies supports high value manufacturing customers through the design and build of special purpose machinery. Application of the research findings in the design of new machines is expected. One application has been identified that would allow faster and more precise dosing of powdered pharmaceutical products into packaging. Company resources have been allocated to the project and will greatly facilitate knowledge transfer, i.e. via secondments, collaborative meetings and assistance with test-rig construction (see statement of support).

(d) General public: Widespread benefits to society are expected from research results being used to improve efficiency of mechanized production and quality of outputs. Environmental benefits associated with the creation of low energy/carbon machines, with the elimination of wear and need for lubrication in such machines, are also expected.

(e) Related entities and initiatives: The proposed project will encompass underpinning research relevant to a number of engineering sectors and research fields. Follow-on benefits to research and innovation on Manufacturing Technologies, Control Engineering, Energy Efficiency, Robotics and Micro Systems are anticipated, as identified in the current EPSRC research framework. The impact of the project aligns well with the strategic priority given to High Value Manufacturing in the UK. The project will promote further technology development. Potential support through the High Value Manufacturing catapult to achieve follow-on gains at TRL 4-7 is anticipated.