McManus, DavidForsyth, PerryYap, Min JetWard, RobertShaddock, DanielMcClelland, DavidSlagmolen, Bram2021-08-060264-9381http://hdl.handle.net/1885/243237Newtonian noise is likely to be a future challenge at low frequencies for Advanced LIGO and other second generation gravitational wave detectors. We present the TorPeDO system: a dual torsion pendulum sensor designed to measure local gravitational forces to high precision. Gravitational forces induce a differential rotation between the two torsion beams, which is measured with an optical read-out. Both torsion pendulums have a common suspension point, tunable centre of mass, and resonant frequency. This produces a high level of mechanical common mode noise cancellation. We report on a controls prototype of the TorPeDO system, presenting the frequency response and tuning range of both pendulums. A noise budget and mechanical cross-coupling model for this system are also presented. We demonstrate frequency tuning of the two torsion pendulums to a difference of 4.3 μHz.BS, RW and DM would like to acknowledge support from the Australian Research Council grant FT130100329 and DP160100760. This paper has been assigned LIGO document number P1700004.application/pdfen-AU© 2017 IOP Publishing Ltdgravitational wavesnewtonian noisetorsion pendulumoptical sensinggravimeter201710.1088/1361-6382/aa71032020-11-23