Meeting Abstract

26.6  Saturday, Jan. 4 14:45  An X-ray-based transducer to measure burrowing biomechanics MOORE, AL*; BARNES, CJ; LEE, DV; Univ. of Nevada, Las Vegas; Univ. of Nevada, Las Vegas; Univ. of Nevada, Las Vegas moorea3@unlv.nevada.edu

The study of burrowing biomechanics has been limited by the technical challenges of 1) tracking motions and 2) measuring forces during subterranean locomotion. We solve the first challenge by using X-ray motion analysis to track skeletal motions of animals as they burrow through a core of soil. We address the second challenge by introducing a device called a Tunnel-Tube that measures the interaction between the animal and the surrounding soil. The Tunnel-Tube is made of a flexible rubber hose sealed inside a rigid outer tube. It measures soil compaction pressure using a pressure sensor mounted to the intertube space. Deflections of an array of ball bearings located at the perimeter of the rubber tube indicate the direction of the forces exerted by the animal. To measure net forces, the entire Tunnel-Tube is mounted on two six-axis load cells. The Tunnel-Tube is calibrated with two pneumatic pistons instrumented with a load cell in each orthogonal axis, providing a known force per unit pressure and millimeter of tube deflection. These calibration data are validated via comparison to a self-driving auger, the “Augerbot,” that has known principles of operation. Our calibrations are applied to burrowing locomotion of a pocket gopher (Thomomys bottae) and compared with results from the Augerbot. The mechanics of burrowing are a function of anatomical specialization for chisel-tooth and/or scratch digging. Thomomys show more specialization for chisel-tooth digging but also use their forelimbs to dig.