Clamp-Force-Centric Estimation and Control for Threaded Fastener Tightening

The clamp force (assembly preload) is central to joint integrity, but variations in friction and embedment make torque- and angle-based strategies inconsistent in achieving a target clamp force. This project takes a clamp-force-centric view of threaded fastener dynamics: we model the joint, evaluate friction models via multibody simulations, and study observability to enable real-time, nonlinear estimation of clamp force from torque, angle, and speed signals. We develop experimentally derived friction maps—the coefficient of friction across tightening speed and clamp load for specific materials and surface coatings. The maps establish a baseline of joint behavior and quantify the expected friction spread, which we use to model uncertainty and to guide estimator and controller design. In doing so, the project advances sensor informatics and decision-making for fastening processes—supporting resilient and sustainable manufacturing.