Application of Carbon Nanotubes to Tensegrity Robots

The structural and electrical properties of Carbon Nanotube Yarns can be used to address certain engineering challenges in tensegrity robots. Tensegrity robots hold great promise due to their flexibility, robustness, and light-weight; but because they are formed from a number of separate rigid components connected only by a network of flexible "tendon" cables, communication of power and data between the components is a challenge. We propose to investigate the use of strong, conductive Carbon Nanotube Yarns as dual-use tendons that can transmit data as well as withstand high loads and active actuation. Beyond Tensegrity Robots, these new multi-function tendons will have a broad impact on all forms of cable driven actuation and the design of lightweight spacecraft and airplanes. NASA is studying tensegrity robots because they offer a lightweight multi-function capabilities for planetary exploration because they can A) collapse and deploy, B) act much like an airbag during landing, protecting a payload, and C) be actively actuated to provide rolling mobility once on the surface. Biological locomotion and animal physiology is also theorized to take advantage of tensegrity principles. Given their ability to absorb significant impact shocks (such as landing), and variable structural compliance, tensegrity robots are well suited for extreme terrain mobility. Yet these capabilities come at the cost that routing power and data cables between the modules is challenging because the modules are only physically connected via structural tensile networks that must also be spooled and actuated. The constant bending and twisting of the tendons makes them unsuitable for steel or copper cables. Current best practices rely on separate power supplies in each module and wireless data links, which introduces certain limitations; such as the wireless links being too slow to integrate system-wide sensory inputs into force based motion controllers. Due to their potential strength, extreme durability, and excellent conductivity, carbon nanotube yarns can serve a multifunctional role as the actuated structural tensile elements, the data and command bus, and as power lines -- thus enabling hardwired data and power networks with greater reliable and less mass compared to the current approach. While the immediate focus of this work is to improve the engineering options for tensegrity robots, success will have significant impact on applications that utilize tendon-based actuation and would also enable the fabrication of multifunctional composites capable of acting as part of a vehicle structure while conducting power and data signals. Use of these composites in aircraft and spacecraft would lead to significant weight reductions by eliminating or reducing the amount of heavy copper wiring that is currently used. This project will develop multi-function tendons capable of routing power and data while also tolerating actuation and structural load transfer. This will significantly advance the application of tensegrity robots for space exploration, along with other cable-actuated systems. More »