Compliant Linear Bearing
The benefits of closed kinematic chain mechanisms with 'Mobility-1' characteristics include self-synchronisation, high predictability and simple actuation. However, these structures are often viewed as undesirable due to a tendency to jam as a result of structural distortion. Oxford Space Systems have developed a Compliant Linear Bearing that has been integrated into a complex Mobility-1 type spacecraft structure and has demonstrably removed the risk of jamming.
Mobility-1, closed kinematic chain motion structures are ubiquitous; they occur in such terrestrial consumer products as display stands, pushchairs, travel cots, deployable trampolines, gazebos etc. They are also of strong interest to the military, space and aerospace communities in as much they permit the realization of readily deployable structures, including communication antennas. However, due the inherent tendency to jam during deployment or stowage, because of structural deformation caused by damage or temporary distortion due to temperature deformation, mobility-1 structures tend to be avoided and more complicated but reliable solutions are selected.
Oxford Space Systems (OSS) has designed, developed and demonstrated a highly tuneable and readily scalable compliant linear bearing that tolerates a significant amount of structural deformation. Thus under conditions where a Mobilty-1 structure would normally jam, the use of the OSS bearing can significantly improve reliable operation. The addition of resistive strain gauge elements within the linear bearing can permit trends in wear to be tracked. In industrial applications where a large number of reciprocations are common, predictive failure becomes a possibility.
A video of the bearing and an application in a deployable circular structure can be viewed online here: http://youtu.be/fbX2Oi5uWDY
Innovations & Advantages
- Significantly reduces the chance of ‘Mobility-1’ type structures jamming
- Enables stowable structures (such as pushchairs, travel cots, gazebos, and trampolines) to be more readily deployed and re-stowed
- Significantly simpler design than is currently being used as an alternative to ‘Mobility-1’ type structures
- Easy to manufacture or as a one-piece injected moulded part – meaning mass production is possible
- Design can incorporate sensors to track displacement trend
Current and Potential Domains of Application
The Compliant Linear Bearing was developed for deployable structures in space, specifically designed to provide a degree of compliance to Mobility-1 architectures. One such example is integration into a deployable outer ring structure for space reflector antennas.
Any terrestrial Mobility-1 structure (i.e. a stowable structure that is over-constrained) could utilise the Compliant Linear Bearing. This includes mass-produced products such as:
- push chairs
- stowable travel cots
- clothes lines
- stowable trampolines
These structures can all benefit from the compliance offered by the highly tuneable and low cost Compliant Linear Bearing design, that will significantly reduce the chance of the structure jamming when deploying or stowing. Identified areas of application for this technology are currently in consumer markets; the slider design is simple yet innovative making it perfect for incorporation into existing products.
The following video is the easiest aid for understanding how the technology can be applied: http://youtu.be/fbX2Oi5uWDY