Switchblade: a nimble treaded rover

Chief architect: Nick Morozovsky
Stabilization software lead: Chris Schmidt-Wetekam
Localization software lead: Andrew Cavender
Sponsors: National Instruments, Los Alamos National Labs

   

The Switchblade concept: a reconfigurable treaded rover.



The Switchblade design and prototype.


Returning to the robust treaded vehicles common in military applications (see the Origins page), we were curious as to the potential performance enhancements possible with feedback control. The result of this study, after a couple of design iterations, is Switchblade, a treaded vehicle that can pop and stabilize both wheelies and stoppies, and can balance on the edge of a stair. The current generation of Switchblade is capable of independently rotating the tread assemblies with respect to the chassis in addition to driving the treads. This allows the robot to dynamically adjust its center of gravity. Inexpensive MEMS accelerometers and gyroscopes, coupled with advanced filtering techniques, allow the robot to estimate its angle with respect to gravity.

With the tread assemblies unfolded away from the body, Switchblade can balance upright on its treaded ``toes'' and stand up to 25" tall in order to expand the view of an onboard camera and overcome obstacles that would otherwise be insurmountable with a 5" tall treaded robot. This design is also capable of both crossing chasms nearly as wide as the vehicle is long, and using the front-mounted pivot of the chassis to actively dampen vibrations when driving quickly over rough terrain. The reconfigurability of the tread assemblies permits several modes of locomotion, which Switchblade can transform between based on the type of terrain encountered. The unique mechanical design of Switchblade coupled with feedback control algorithms enable it to overcome complex terrain (e.g. stairs, rubble) while retaining a small form factor to navigate in confined spaces and to reduce cost and weight.

Switchblade was built using the high-performance National Instruments sbRIO 9602 board, and was programmed using both low-level coding in C as well as high-level control design leveraging LabVIEW's CD&Sim module.