Active control for mid-span connection of a deployable tensegrity footbridge

Abstract

Tensegrity structures are spatial self-stressed pin-jointed structures where compression components (struts) are surrounded by tension elements. This paper describes a near full-scale deployable tensegrity footbridge that deploys from both sides and connects at mid-span. Two topologies that differ in terms of symmetry of elements and paths of continuous cables are compared. Although both topologies behave similarly with respect to serviceability criteria, there is a significant difference in behavior during deployment. A two-stage control methodology for the connection of both halves of the footbridge is presented. The control methodology determines active cable length changes based on computational control and measurement of the response of the structure during deployment. Both halves are successfully connected at the end of deployment.

Generation of planar tensegrity structures through cellular multiplication

“…For example, modifying self-stress according to an equilibrium manifold (a continuous set of solutions of the self-stress problem) can allow a tensegrity structure to remain stable throughout shape transformations [23]. Changes in the shape of tensegrity structures can thus be controlled by element-length modifications obtained through the integration of active elements [8][9][10] or smart materials [27][28][29]. Moreover, since the self-stress guarantees stability in tensegrity structures, the existence of multiple self-stress states increases the chances of survival after a member removal.…”

“…This property of function f derives also from its definition as the cross product − × . Repeating the process for Equations (7) to (9) allows to find the other self-stress components, and the self-stress state w can be written as:…”

Shape change analysis of tensegrity models

“…Shape change of tensegrities have been studied and applied especially for the design of deployable structures and robots. Specifically, the use of tensegrities as deployable structures has been proposed for space applications (Fazli andAbedian, 2011, Dalilsafaei et al, 2012), deployable beams (Averseng et al, 2012), deployable support for solar energy harvesting on water canals (Carpentieri et al, 2017), deployable footbridge (Rhode- Barbarigos et al, 2012, Veuve et al, 2016, composite solar façades and wind generators (Cimmino et al, 2017), and compressive structures (Skelton and Oliveira, 2010). Furuya (1992) was probably the first researcher to use tensegrity as a deployable structure even though the investigation was at the conceptual level.…”

“…An example of a 6-bar tensegrity to move from an initial shape to the target shape was achieved through active cables with the alteration of stored elastic energy. Veuve et al investigated a control methodology to connect two half bridges through the changes of cable length (Veuve et al, 2016). The deployment of the footbridges was solved based on the distance between a pair of nodal coordinates of two mid-span connectors.…”

Deployment and Shape Change of a Tensegrity Structure Using Path-Planning and Feedback Control

“…In the first deployment stage, it was observed that empirical deployment resulted in large variations in end-node coordinates. In a second stage, control feedback, proposed by Veuve et al (2016), has enabled subsequent control-commands that join the connector nodes and ensure successful locking of the two halves. Although control cases were reused by Veuve et al (2017) for faster and effective control during midspan connection, the deployment trajectory was often uneven, thus limiting efforts to further reduce deployment time.…”