Travelling Wave Generation in Soft Robotics

Travelling waves are abundant in natural organisms, they are found in worms, millipedes, cuttlefish and even within the human body. In crawling and swimming organisms, this mechanism is often central to their locomotion, whilst peristalsis and mucociliary transport play a critical role in human physiology. Generating travelling waves in robotic systems could create new opportunities for novel locomotion strategies in sensitive and unconventional environments and the capacity to translocate multi-phase matter. However, the biological example is a difficult one to follow; here a very large number of microscopic muscle fibres are activated in series to produce a smooth travelling wave. Actuation and control on this scale is impractical to reproduce with current approaches, although, an approximation with a reduced number of active elements (generally <10) is commonly used when making bioinspired robots, such as servo driven cuttlefish [1] and worm robots [2][3]. The main drawback to this approximated approach using discrete actuators is that the number of active elements scales with the fidelity of the approximation, bringing undesirable increases in complexity, cost, number of actuators/valves and degrees of control if a smooth wave is required (Figure 1). Reducing unnecessary degrees of control, actuators and valves would provide benefits by potentially enabling softer, cheaper and more robust soft robots. While programmable shape change is possible with a singular fluidic input at present, making non-uniform changes to pressure throughout the robot (for example, sequentially inflating and deflating different areas) is difficult to achieve through morphology alone.

In this PhD, mechanisms for producing a travelling wave using soft robotic technologies will be investigated with the aim of eliminating the current limitations of scaling and low fidelity. This will create a new class of flexible travelling wave systems that can be exploited for low impact locomotion, conveying and peristaltic pumping. Research gaps in this design space (as shown in Figure 1) will be addressed by answering several key questions:
How can multiple wave fronts be simultaneously generated in the robot without a concomitant increase in the number of actuators and control signals?
How does the travelling wave mechanism scale with size/length/width?
How effective is the mechanism for locomotion in various environments?
What characteristics of a travelling wave are useful for matter transport and can these be integrated into a robotic system?
Initial work will focus on the continuation of the Blockworm design, which generates a travelling wave in a soft worm-like body from only two actuators [4] (developed during the previous masters dissertation and submitted to the IEEE International Conference on Soft Robotics 2020). As the project continues, a wider focus on the methods of generating travelling waves in soft bodies will commence.
Applications of travelling waves in robotics are diverse. For locomotion alone, travelling waves can be applied to traverse flat terrain, media such as soil, sand or sludge and confined channels, such as pipes or the human body (and possibly combinations of the above in one robot). Such adaptability is an aspiration of soft robotics with direct application to surgery (e.g. arterial stent placement), disaster recovery, pipe inspection, nuclear decommissioning and more. Outside of locomotion, travelling waves could be used for the transport of fragile items, such as fruit and other produce. These could be peristaltic waves like those found in the human windpipe and gastrointestinal tract, or a flat sorting table. The principle could also be applied to wearable devices in a massaging function, for example used to stimulate blood flow in the legs post-surgery or on long flights, reducing the risk of deep vein thrombosis.

Rapid growth in the already burgeoning Robotics and Autonomous Systems (RAS) market has been estimated from many sources. This growth is driven by socio-economic needs and enabled by advances in algorithms and technologies converging on robotics. The market potential for applications of robotics and autonomous systems is, therefore, of huge value to the UK. There are four major areas where FARSCOPE will strive to fulfil and deliver on the impact agenda.

1. Training: A coherent strategy for impact must observe the value of the 'innovation pipeline'; from training of world-class researchers to novel products in the 'shop window'. The FARSCOPE training programme described in the Case for Support will produce researchers who will be able to advance knowledge, expertise and skills in the many associated aspects of academic pursuit in the field. Crucially, they will be guided by its industrial partners and BRL's Industrial Advisory Group, so that they are grounded in the real-world context of the many robotics and autonomous systems application domains. This means pursuing research excellence while embracing the challenges set within the context of a range of real-world factors.

2. Economic and Social Exploitation: The elevated position of advanced robotics, in the commercial 'value chain', makes it imperative that we create graduates from our Centre who are acutely aware of this potential. BRL is centrally engaged in its regional SME and business ecology, as evidenced by its recent industry workshop and 'open lab' events, which attracted some 60 and 280 industrial delegates respectively. BRL is also a key contributor to regional economic innovation. BRL has engaged two business managers and allocated some dedicated space to specifically support work on RAS related industrial engagement and innovation and, importantly, technology incubation. BRL will be creating an EU-funded Robotics Innovation Facilities to help coordinating a EUR 20m a programme to specifically promote and encourage direct links between academia and industry with a focus on SMEs. All of these high-impact BRL activities will be fed directly into the FARSCOPE programme.

A critical mass of key industrial and end-user partnerships across a diverse array of sectors have given their support to the FARSCOPE centre. All have indicated their interest in engaging through the FARSCOPE mechanisms identified in the Case for Support. These demonstrate the impact of the FARSCOPE centre in engaging existing, and forming new, strategic partnerships in the RAS field.

3. Fostering links with other Research Institutions and Academic Dissemination: It is essential that FARSCOPE CDT students learn to share best practice with other RAS research centres, both in the UK and beyond. In addition to attendance and presentation at academic conferences nationally and overseas, FARSCOPE will use the following mechanisms to engage with the academic community. BRL has very many strong links with the UK, EU and global RAS research community. We will use these as a basis for cementing existing links and fostering new ones.

4. Engaging the Public: FARSCOPE will train and then encourage its student cohorts to engage with the general public, to educate about the potential of these new technologies, to participate in debates on ethics, safety and legality of autonomous systems, and to enthuse future generations to work in this exciting area. UWE and the University of Bristol, BRL's two supporting institutions, host the National Coordinating Centre for Public Engagement. In addition, UWE's Science Communication Unit is internationally renowned for its diverse and innovative activities, which engage the public with science. FARSCOPE students will receive guidance and training in public engagement in order to act as worthy RAS research 'ambassadors'.