ESSENCE: Embedding Softness into Structure Enabling Distributed Tactile Sensing of High-order Curved Surfaces

Tactile perception is essential for robotic systems to perform tasks efficiently involving physical interactions with the environments such as carrying out assembly tasks or manipulating objects in manufacturing, in particular in uncontrolled environments. Research has shown that the efficiency of human manipulation is largely based on the sophisticated tactile afferents distributed across the human skin. If the tactile sensory system of human skin is neurologically damaged, a person significantly loses the efficiency for manipulation. Human tactile perception is still far beyond that of tactile sensing technology hitherto. To narrow the gap, extensive research has been carried out to develop robot skin with distributed tactile sensing elements (tactels). The existing tactile array sensing methods commonly utilize piezoresistive or capacitive materials, strain gauges, conductive elastomer or liquid and fiber-optics. While tactile sensing technologies have dramatically advanced in regards to spatial resolution, sensitivity, sensor flexibility and stretch-ablity, one major unsolved problem is to provide distributed tactile sensing capability to complex structural surfaces, which are normally described use high-order polynomial geometric equations, such as quadratic ellipsoidal surfaces, especially with small radii.The existing flexible and stretchable tactile array sensors are fabricated in the form of a film, thus difficult to be attached to those high-order polynomial surfaces. Since those surfaces are commonly used in various engineering designs, this problem significantly reduces the applicability of existing tactile array sensing methods.

This project proposes a novel method to solve this bottleneck by utilizing 3D printing technique to embed distributed sub-millimeter soft material channels within that structure. Forces applied to the structure surface will induce micro deformations of the soft material channels. Thus those soft material channels act as tactile afferent fibres within human tissue providing distributed tactile information on the structure. Through the project, we aim to develop the general principles of using the proposed method for accurate and robust tactile sensing.

Compared to existing tactile array sensors, the proposed method provides the capability of placing the tactels on a structure with arbitrary surfaces according to bespoke designs; it requires simple fabrication processes and is easy to be applied to miniaturized structures; the proposed method is also cost effective for providing large number tactile sensing elements.

The immediate project success will be assessed based on the achieved tactile sensing performance compared to the current state of the art commercial tactile array sensors, as well as the reliability and adaptiveness of the proposed method demonstrated in our exemplary application with SHADOW. The long-term success of the project will be measured by the takeup of the proposed sensing principles that we shall develop by both the academic communities and industries.

The project will directly benefit sectors of the UK economy including robotics and autonomous systems industries, healthcare technology industries, and manufacturing industries. The technology advancements that shall be brought by this project are applicable for improving the health and safety in both manufacturing settings and healthcare services. In addition, experience gained by the Research Associate working on this multidisciplinary project creates a skill set useful in many scenarios.

1. The robotics and autonomous systems industries will be primary beneficiaries of this project. Robotics is of national importance for the UK. It is considered to be one of the eight great technologies for the future. The technical challenge, fabrication complexity paired with the associated cost for equipping a robot body with distributed tactile sensors have significantly hindered the takeup of tactile sensing technology by robot manufacturers. This project will provide robot manufacturers a customizable and cost effective solution for enabling distributed tactile sensing on an arbitrary structure. Thus the proposed research and the transfer of research findings to the industrial collaborator have the potential for significant contribution to the UK's competitiveness in those industries. In addition, the healthcare technology sector requiring tactile sensing technologies, such as manufacturers for medical and prosthetics devices will also be a beneficiary of this project owing to the adaptiveness, biocompatibility of the proposed tactile sensing method.

2. This project will benefit the UK's manufacturing sector. The manufacturing sector increasingly demands robotic and automation systems that can assist human workers to increase productivity especially in low-volume/high-variation manufacturing settings. Providing a robotic system with distributed tactile sensing capability will be essential for the interaction with environment and human workers, ensuring the health and safety as well as the task efficiency. Similarly equipping tactile sensing capability to instruments used in medical treatments will increase the awareness of clinicians in the interaction between the instruments and human body, benefiting patient safety and treatment efficiency.

3. Lastly, the Research Associate working on the project will gain practical experience in computer-aided design, 3D printing, finite element modelling, mechatronics system design, as well as the opportunity of working with the industrial partner for robotic system integration. This skill set can be applied in a wide range of engineering sectors, and is becoming an increasingly valuable as both academic communities and industries in the field of robotics are growing rapidly.