In this section we will explore a progression from technological research and developments in electronic-textiles and fiber-electronics to projects in the emerging field of soft-architecture robotics and finally diverse combinations of clothing and robotics from both the technology sector and the world of fashion. These examples should provide an understanding of how these varied themes could merge together into sartorial robotics.
The fundamental qualities of robotics, sensing, actuation and computation can all be seen moving from traditional rigid components towards softer fiber and textile morphologies. Electrically conductive textiles and fibers have been available for some time. Conductive fibers have been woven into textiles for decorative purposes such as metallic silk organza, made of silk thread wrapped in a copper foil, which eventually was utilized in electronic applications and wearable electronics [REP97]. Current research into carbon nanotube (CNT) dyed threads results in conductive fibers and thread that retain their relative flexibility and twist consistency which would allow them to be integrated in the apparel making process. Some CNT dyed conductive threads have achieved consistent electrical conductivity variation when stretched so that they have actually been utilized as strain gauges [Pan07]. Other CNT dyeing techniques have shown considerable promise towards creating textile based energy storage devices utilizing carbon nanotubes and lithium cobalt oxide (LiCoO2) nanoparticles. The absorption properties of the textile fibers help the nanoparticle dye saturate the material and increase its efficiency. The change in morphology would be well suited for wearable applications [HuL10]. The textile based energy storage devices are reported to remain flexible and stretchable like fabric and are washable as well.
Figure 2-7. Single fiber-electronic devices approximately 500 - 900 µm in diameter capable of optical, acoustical and thermal excitation and incorporating semiconductor junctions (Abouraddy et al. 2007).
Another promising area for exploration involves manufacturing techniques within the photonics industry that could be expanded to include fiber-electronic production. The tapered preform-based fiber-drawing method, similar to the process used in the manufacturing of silica glass fiber optics for the telecommunications industry, shows considerable promise for producing fiber-electronic devices. Conductors, semiconductors and insulators, the basic components of electronics and optoelectronics, have been fabricated together in single fiber-electronic devices which range from 500 - 900 µm in diameter [Abo07][Sor07]. The technique has the potential to change the morphology of electronic components from the dominant chip/planar geometry construction to fiber-like geometries capable of textile construction Figure 2-7. "This is the first time that anybody has demonstrated that a single plane of fibers, or 'fabric,' can collect images just like a camera but without a lens," said Professor Yoel Fink the project’s principle researcher[Eli09]. Optical, thermal and acoustic sensing devices have been developed with this method as well as semiconducting junctions like p-n junctions, the foundation for logic operations.
In addition to sensors, fiber based actuators are being developed as well from materials like electroactive polymers (EAP) and shape memory alloys (SMA). However, these materials often lack a significant amount of mechanical force so their applications have been limited. Recent research from the Nanotech Institute at the University of Texas has produced carbon nanotubes that have been spun into yarns that exhibit artificial muscle properties that can exert approximately 100 times the force per area than that of natural muscle[Bra09]. These examples show traditional rigid electronic components progressing towards fiber and textile morphologies that could be either literally the material of clothing i.e. fibers, yarns and textiles, or mimic the materiality of clothing in flexibility and conformability making them suitable for the design of soft-architecture robotics.
In this section we will look at examples of soft-architecture robotics, some of which utilize the materials discussed previously and others which make use of traditional textiles. The Origami Robot by Harvard University and MIT researchers, Robert Wood and Daniela Rus, is a programmable sheet material that can autonomously fold itself into a variety of shapes. The planar robotic surface is divided into hinged triangular sections that can bend using shape memory alloy (SMA) actuators which can be activated with heat, Figure 2-8. The SMA actuators are located along predetermined crease patterns to transform from a flat sheet into a three-dimensional form[EHa10]. The origami robot is an example of a robot exhibiting a flexible planar surface morphology which as a surface can be played with and morphed.
Figure 2-8. Harvard University and MIT researchers created a self-folding origami surface.
Other soft-architecture robotic research focuses on elastomer materials and pneumatics for novel actuation techniques. For example, iRobot’s Chembot is designed to be a soft morphing robot and uses a process called jamming in order to move, Figure 2-9. Jamming requires a flexible silicone skin with compartments of loosely packed granular material which under a vacuum forces the granular material together and makes it more rigid.
Figure 2-9. iRobot’s Chembot elastomeric materials and pneumatics for locomotion.
Releasing the vacuum returns it to a flexible state. Electroactive polymers (EAPs) are also being used to create electroactive polymer artificial muscles (EPAMs). Researchers at the Auckland Bioengineering Institute are using EAPs that can expand and contract up to 300 percent when a voltage is applied[Don11]. With these materials they have been able to create soft, flexible motors that have none of the traditional rigid components like electromagnets, wire coils or gears. With this shift towards softer and more flexible robots their new aesthetic will influence human-robot interaction design. Therefore investigating other soft and flexible cultural artifacts, such as clothing, will become crucial in understanding how this soft-architecture will be situated.
Figure 2-10. Otherlab’s low-cost, pneumatically controlled, inflatable robot, Ant-Roach.
Ant-Roach by Otherlab is an inflatable robot that gets its form from textile-air-structured forms and is capable of motion through textile-pneumatic actuators Figure 2-10. The textiles are relatively low-cost and when deflated can be folded up into a compact package for easy transport. While textiles offer some advantages over traditional rigid robotic components they also present some problems. For example, traditional actuation in robotics might be achieved with servos or motors with shaft encoders allowing for very precise rotational control (radians per second). With soft-architecture robotics with textile-pneumatic actuators, like those in Ant-Roach, there are no shafts to encode nor even a precise axis of rotation. They might then rely on estimated open-loop control. However, with the addition of fibers or textiles that can sense force or strain, feedback can be introduced into the system for improved accuracy.