Fingerbasis

Fingerbasis is a term used in biomechanics and robotics to denote a reference point on a finger used to resolve forces and moments during grasp and manipulation. The basis point can be defined variably: as the center of pressure on the finger pad, a fixed anatomical landmark, or a fitted point from sensor data, depending on the model and experimental setup. The fingerbasis serves as the origin for expressing the contact force vector and calculating moments about finger joints, enabling simplified representations of complex finger-ground interactions.

In practice, researchers select a fingerbasis to suit the task: for rigid-body models, a fixed landmark near the distal phalanx; for compliant models, the center of pressure on the contact area. Force and torque are decomposed into normal and tangential components relative to the finger surface, as well as into cross-joint moments about the finger axes.

Measurement methods include pressure-sensitive sensors, instrumented gloves, and motion capture, often combined with inverse dynamics or finite-element modeling to estimate the fingerbasis location under different postures.

Applications span robotic grippers and prosthetic hands, virtual reality haptics, ergonomic design of handheld devices, and animation of believable hand movements.

Limitations include variability with grip type, skin deformation, and pose; the fingerbasis is a modeling construct rather than a uniquely defined physical point, and estimates carry uncertainty.