​Tensegrity Autonomous Deployable Millirobots for Minimally Invasive Interventions​

“Milli-scale robots have emerged as next generation of intelligent technology for minimally invasive interventions, which call for autonomous millirobots to work as tiny “surgeons” or drug delivery “vehicles” to achieve in-vivo practices. It is beneficial to have a systematic approach to creation of autonomous millirobots with (1) simple and reliable mechanisms for morphing, and (2) an effective locomotion system. However, these two objectives are difficult to achieve due to the lack of well-established tools for milli-scale structural design, fabrication, locomotion planning and actuation development. Traditional millirobots with soft bodies mainly rely on complex, low stiffness or even fragile joints or mechanisms for morphing, which is an issue if high operational reliability is required. The problem even aggravates when a millirobot operates in a high-pressure environment. Other traditional millirobots are designed as remotely actuated rigid metal particles or structures, which prevents the robots from morphing in a flexible manner. Therefore, these millirobots will inevitably suffer a high risk of retention in small spaces during navigation.”

​Effective ADMs Design: Tensegrity Approach

​A new framework of effective ADMs design by the tensegrity-structure-based approach at milli-scale level is developed. This design emphasizes: (a) class-1 tensegrity for straightforward, reliable joints, (b) uniform member lengths for streamlined fabrication and minimized external load sensitivity, and (c) individualized bar creation and unified cable networks for simplified assembly.

​​Bio-mimic Locomotion System

This research seeks to design a bio-mimic locomotion system for tensegrity ADMs inspired by earthworm movement. These ADMs will employ optimally placed active cable members, powered by shape memory alloy actuators, to achieve body morphing. Just as earthworms utilize segmented, flexible bodies to navigate tight soils, tensegrity ADMs will have reconfigurable units for axial morphing, facilitating deep burrowing in compact tissues. This innovative approach, emphasizing unidirectional morphing, ensures efficient navigation in restrictive spaces and energy conservation, setting it apart from conventional bending-based locomotion systems.

Optimal placement of active cable members for a reconfigurable tensegrity unit cell: (a) simulation of deployed unit cell; (b) simulation of folded unit cell; (c) deployed macro-scale prototype; (d) folded macro-scale prototype.
Locomotion planning of a tensegrity ADM

References

  1. Kazoleas, C., Mehta, K. and Yuan, S., 2022, October. Prototype Design and Manufacture of a Deployable Tensegrity Microrobot. In ASME International Mechanical Engineering Congress and Exposition (Vol. 86649, p. V02BT02A055). American Society of Mechanical Engineers. doi: 10.1115/IMECE2022-93929
  2. Yuan, S., Jing, W. and Jiang, H., 2021, November. A deployable tensegrity microrobot for minimally invasive interventions. In ASME International Mechanical Engineering Congress and Exposition (Vol. 85598, p. V005T05A061). American Society of Mechanical Engineers. doi: 10.1115/IMECE2021-67009