Introduction

The 9th March 2016 was the 50th anniversary of the landmark “Jost Report – Lubrication (Tribology) Education and Research” . The word Tribology was born and the dramatic financial savings that could be gained by optimum practice in this area were formally documented for the first time. 50 years on, the impact of tribology (friction and wear) on the economies of developed nations remains the same; 5-8% of GDP; but tribology as an engineering science has evolved. Tribology challenges in 2016 and beyond are driven by new challenges; the challenges in 1966 were solved and new challenges go with the emergence of new industrial areas.

The basic science of tribology remains the same but there is a need to embrace multi-scale thinking, complex materials and interfaces and systems to operate in new and demanding
environments. In this proposal Tribology as an enabling technology will be integrated into two industrial areas that are underpinning for the UK and internationally; advanced manufacturing and robotics and autonomous systems. The proposal is transformative as it brings tribology, as a positive and enabling discipline, into two emerging areas of nanomanufacturing
and robotics.

Tribology is normally associated with the wear and degradation and whilst important to the economy normally has negative connotations.

Project Summary

The key aim of TRENT is to introduce tribology as an enabling technology in the engineering of intelligent systems for manufacturing and robotics. This will be facilitated
through collaboration with teams from Norway (NTNU); Germany (Max Planck) and the US (Caltech). Our study has the potential to have significant impact across a number of application
areas (for example, transport, healthcare, energy (nuclear, offshore etc.)). This will only achieved through a well-defined strategy for dissemination to, and collaboration with academia and industry.

Research Challenges

The International Centre-to-Centre introduces tribology as an enabling technology; through the detailed understanding of the interfacial processes at complex interfaces across length scales we can affect significant changes in the engineering of intelligent systems for manufacturing and robotics. The challenges we hope TRENT can address are as follows:

1) Nanomanufacturing; The dawn of new tribonanoprinting processes and assisting in the step towards 4D printing

3D printing is arguably driving the manufacturing revolution of the 21st century. It is changing the way we construct engineering systems, plan for major surgical procedures and how we personalise medical implants. 3D printing at the nanoscale (conventionally with dip pen lithography) has some intrinsic limitations, notably the lack of precision in movement
and the complexities of delivering ultra-small amounts of materials to a precise location.

There is no current technology for 3D printing at the nanoscale that is void of these limitations of delivering an active fluid through a fine nozzle/aperture. Since the introduction of the term in 2013 4D printing has captured the imagination of some of the most innovative material scientists and involves the printing of stimulus responsive materials. At the heart of this is the ability to produce a nanoscale composite in-situ.

It is against these challenges that nanoscale tribochemistry is introduced. In Leeds we have recently been using the Atomic Force Microscope (AFM) to study tribochemical processes. These are reactions that occur when two surfaces in a lubricant containing additives come into intimate contact. The relative motion, the generated friction and the uncovering of nascent material all provide the conditions which lead to the formation of reacted layers called tribofilms. These studies have fulfilled our initial aim to isolate single asperities and to quantify the kinetics of tribofilm formation but they provide something that has created a great excitement; a potential novel approach to 3D printing on the nanoscale. The tribocontact creates a 3D structure and is “printing”.

Tribo 3D printing has the ability to become a serious contender as a technology for building accurate and controllable nanostructures.

2) The tribology of grasping; the central constraint in efficient robotic manipulation

The field of robotics and autonomous systems is exploding and robotic systems will provide some of the most interesting challenges for engineers in the coming years. Robotic systems are invariably deployed to provide efficient, reliable and non-destructive manipulation of components/devices to provide an enhancement of engineering system performance. As such, the interface between the robotic system and the substance being manipulated is crucial. This can range in complexity from rigid objects with repeatable shapes and surface textures (in many industrial assembly operations) to soft, compliant material which is wet and has variable properties (like in surgical robotics for laparoscopic surgery).

Central to all of these applications is that tribology dominates the performance of grasping. It is the case that in the Industrial Strategy Challenge Fund advisory committee a poll of the robotics industry highlighted grasping as the main limitations of many robotic systems and confirmed the need for a sustained effort in this area. Tribologists can provide the underpinning engineering science to assist roboticists in ensuring grasping technologies keep pace and align well with robotic development.

In developing a computational and experimental framework for the evaluation of grasping in complex environments tribologists will help to facilitate an improvement in robotic system safety and efficiency.

3) Tribology as a central design constraint in mobile robotics

Mobile robotics have wide ranging applications in pipe inspection in the oil and gas and water networks, search and rescue environments and in medical applications. In medical applications the locomotion of intracorporeal or intraluminal robots has the potential to transform investigative procedures like colonoscopy and other endoscopies. The recently-completed ERC Advanced investigator grant held by Neville (CoDIR) developed a robot (Rollerball) to traverse the inside of the colon cavity in a water-flooded environment. Other types of autonomous and semi-autonomous robots to traverse soft tissue environments are in development and the development of the device/tissue environment poses great challenges for engineers.

There is a great opportunity to “tune” the tribological interface such that traction can be optimised to prevent device slippage but that the minimisation of damage to the endothelial layers is also achieved. The tribologists in Leeds and Sheffield have both been progressing their understanding of the interface between tissue and medical devices through work on colonic probes, surgical graspers, surgical gloves and catheters. Dwyer-Joyce has also been developing ultrasonic sensors that detect highly localised interface conditions that would give robotic feedback in grasping. At the small scale the development of robots is the core of the activities of Setti and his group in Max Planck.

Micro-scale mobile robots can be optimised through a detailed understanding of the interfacial tribology, interface sensing, and the development of a computational/experimental framework for such.