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Self-HEaling soft RObotics

Periodic Reporting for period 2 - SHERO (Self-HEaling soft RObotics)

Reporting period: 2020-06-01 to 2022-11-30

The radical vision of the SHERO project is the ambitious development of fully-autonomous self-healing soft robotic devices, by integrating engineered functional materials, smart sensing and active actuation and control capabilities into soft robots. These soft robotic systems will be able to sense and evaluate loss of performance and heal damage due to fatigue, overloading, and injuries by sharp objects present in dynamic environments or by human contact. Such fully integrated self-healing robotic systems – and by extension other devices, machines and structures – are unprecedented in scientific literature. This project will challenge the limits of current state-of-the-art research to fortify the foundations for all three pillars of mechatronic design: actuation, sensing and control, supported by advanced material design. Merged into prototypes and demonstrators, these fundamental principles are further refined in view of a synergistic development of more complex and autonomous robotic systems. The results of the project will reach further than the already broad field of robotics and automation. These concepts can be implemented in both dynamic and static applications and environments. The combination of material systems containing passive and active healing mechanisms with smart sensory capabilities could revolutionize automotive, aerospace and naval industries, on- and offshore energy production, manufacturing and construction sectors, illustrating the overarching impact of this pioneering technology on the development of more reliable and sustainable products, finding applications throughout society.
The breakthrough targeted in the project is the development of complete robotic systems that are able to feel pain (sense microscopic and macroscopic damage), react intelligently to relieve the pain (evaluate performance and prevent catastrophic failure), take the necessary measures to heal the damage and to restore all functions (induce or facilitate a controlled autonomous or non-autonomous healing of damaged elements), perform a rehabilitation (evaluate the quality of the healing process and take measures accordingly), and, finally, return to action. The unique, integrated design of SH capabilities in robotic systems with intelligent control will lead to lighter, more efficient, more reliable and more sustainable designs, as preventive and corrective healing will drastically increase the performance lifetime and reliability of such systems, even under unpredictable conditions.

The following three research objectives will be pursued:
Development, characterization and tuning of self healing materials and its processing techniques for complex geometries and intelligent design.
Development of self-healing actuator systems, deformation and damage sensing capabilities and dedicated smart control and response system.
Development and validation of fully autonomous self-healing demonstrators with dedicated intelligence.
The work started with the synthesis and characterisation of reversible networks (Self-healing polymers) based on Diels-Adler (DA) based networks (including room temperature healing and materials with different mechanical properties), hydrogen bond based networks and vitrimers exchange reaction based networks. Based on this also the synthesis and characterisation of reversible networks with additional functionality were realized using magnetic particles in self-healing polymers material for magnetic self-healing polymers and conductive fillers in reversible networks to obtain conductive properties. The latter was for the development of self-healing sensors. Several manufacturing and processing of reversible networks into soft robotics were developed: Moulding of self-healing polymers, Shaping through folding & covalently binding, Fused filament fabrication (3D) printing of reversible networks and Laser cutting/welding of Reversible networks. These innovative materials and processing techniques were demonstrated in several soft robotics demonstrators, mostly different robotic grippers and hands.

Moreover a review paper on self healing polymers for soft robotics is developed, which aims to bridge between the self-healing materials research field and the soft robotics community. From a first literature study it is concluded that soft robots are volnurable and can be damaged through various damaging modes, including fatigue, delamination, overloading, tendon cut and by sharp objects. This stressed the need for a healing ability which allows to recover from these damages and consequently reduce maintenance in and the ecological impact of future robotics. However, to provide an economical and ecological solution for the volnurability of soft robots, the SH polymers that can be used need to meet five basic criteria, proposed in this review. Based on these, SH mechanisms with limited potential are excluded. For the remaining, based on performance parameters, including mechanical strength, healing efficiency and healing times, examples with exceptional suitable properties for soft robotics were sought in the literature, listed and compared. Throughout the paper, it discussed how the underlying chemistry impacts the performance parameters, which are provided in overview tables. From this extensive analysis it is conclude, that taking in account some limitations and trade-offs in material properties, many SH mechanisms can be directly used to construct healable soft robotic components.
The SHERO project has kickstarted the development of fully-autonomous self-healing soft robotic devices, by integrating self-healing materials, smart sensing and active actuation and control capabilities into one soft robotic device.
Already from the start, a large exposure in popular press has been achieved by the project, highlighting not only its public relevancy but also how well this marriage of self-healing and soft robotics resonates with the general public. Highly motivated by this public resonance, the SHERO-team is currently performing its research to develop working demonstrators that amalgamates the expertises of all partners. These demonstrators will be used to bring the innovation to a higher TRL and to gain interest for further R&D and for commercial interest. Indeed, a first spin-off of SHERO has already been generated by the start of the SMART Innovative Training Network, which is a joint venture between academia and industry centered around the multidisciplinary fields of soft robotics and smart materials. Additionally, other European and national funding schemes are targeted by the partners.
SHERO’s unprecedented integrated approach targeted at lighter, more efficient, more reliable and more sustainable robotic designs, will drastically increase the performance lifetimes and reliability of soft robotic systems. Additionally, it will contribute to the ‘Circular Electronics Initiative’ as recently started by the European Commission. Clearly, these results will not only be used to target the soft robotics community, but also other application areas, all benefiting from more reliable and sustainable products thereby eminently targeting the need for a circular economy in Europe.
3D printed soft self healing robot gripper
multi-material self healing soft gripper
room temperature healing material in soft robotic hand