Virtual mapping of an anatomical pivot point and alignment therewith

摘要

A system and method is provided for resolving a pivot point via touchless interaction. It applies to situations where one end of a rigid object is inaccessible but remains stationary at a pivot point, while the other end is free to move and is accessible to an input pointing device. As an example, the rigid object can be a leg bone where the proximal end is at the hip joint and the distal end is at the knee. The system comprises a wand and a receiver that are spatially configurable to touchlessly locate the pivot point without contact. The receiver tracks a relative displacement of the wand and geometrically resolves the location of the pivot point by a spherical mapping. The system can use a combination of ultrasonic sensing and/or accelerometer measurements. Other embodiments are disclosed.

主权项

1. A method for determining an anatomical pivot point and alignment therewith, the method comprising the steps of:
transmitting ultrasonic signals from an ultrasonic wand to an ultrasonic receiver, where the ultrasonic receiver is attached to a first end of a bone, the bone comprises two ends, and a second end of the bone is sufficiently stationary; determining paired transmit-receive ranges between the ultrasonic wand and the ultrasonic receiver by weighted time of flight and phase differential measurements of the ultrasonic signals captured and processed at the ultrasonic receiver; tracking the ultrasonic wand by way of, and relative to, the ultrasonic receiver during constrained rotational and translational movement at the first end from the paired transmit-receive ranges while the ultrasonic wand is positioned stationary, in proximity and in-sight of the ultrasonic receiver; calculating a three-dimensional displacement and orientation time trajectory of the ultrasonic wand relative to the ultrasonic receiver from the tracking of the ultrasonic, wand and the time of flight and phase differential measurements; generating a hemispherical surface representation of the constrained movement at the first end of the bone from the three-dimensional displacement and orientation time trajectory; and calculating a pivot point of the second end of the bone from the hemispherical surface representation of the constrained movement relative to a predetermined origin of the ultrasonic receiver at the first end of the bone.