The optical torque wrench is a laser trapping technique that expands the capability of standard optical tweezers to torque manipulation and measurement, using the laser linear polarization to orient tailored microscopic birefringent particles. The ability to measure torque of the order of kBT (∼4 pN nm) is especially important in the study of biophysical systems at the molecular and cellular le...

This paper presents an approach for stiffness modelling of the lower mobility parallel manipulators using the generalized Jacobian. The approach can be implemented by two steps:(1) The first order deflection analysis by decomposing twist space of the end-effector into a pair of complementary twist subspaces associated with the permitted and restricted instantaneous motions, (2) The kinestatic a...

In this paper a unified contact force control approach for cable-driven parallel robots (CDPR) is proposed. The contact force controller is governed by two control loops: 1) An inner impedance control loop enforcing a dynamical relationship between the internal forces and the end-effector velocities to maintain a desired tension level in the cable system. 2) An outer admittance control loop con...

The contribution of this paper is the expansion of the range of possibilities in the analysis, planning, and control of contact tasks. The successful execution of any contact task fundamentally requires the application of wrenches (forces and moments) consistent with the task. We develop an algorithm for computing the entire set of external wrenches consistent with achieving a given augmented c...

One of this year’s Oscar-winning movies, The Big Short, tells the entertaining story of a ragtag bunch who foresaw and capitalized on the housing bubble of the mid-2000s. The factors contributing to economic bubbles and their collapses are complex and heavily debated, but getting a clearer picture of how they arise and how we might avoid them in the future would seem particularly important as o...