Today, the U.S. Patent and Trademark Office officially granted Apple  a patent relating to object sensing systems, and more particularly, to detecting and tracking one or more objects such as an Apple Pencil, smart glove and more using radar.

In Apple's patent background they note that proximity sensing systems (systems that can detect both touching and hovering objects) often require an array of sensors across a large surface area to enable object detection, and when proximity sensing arrays are placed over displays, image quality of the display can suffer. Furthermore, the object detection range of proximity sensing systems is often limited, and the position and motion sensing resolution of these systems is often limited by the number and size of sensing elements in the array. Because of these limitations, alternative systems such as ultrasonic sensing systems and radar sensing systems have been developed that use triangulation to detect objects. However, when the object (e.g., a stylus) requires very accurate position detection with sub-millimeter accuracy, for example, even these systems can suffer from inadequate position detection accuracy. This is what Apple's granted patent addresses. 

Ultra-Accurate Object Tracking using Radar In Multi-object Environment

Apple's granted patent relates to detecting and tracking one or more objects of interest (e.g., one or more styluses, fingertips of a glove) with improved accuracy using radar-based tracking systems. In some examples, multiple radars implemented in a device (e.g., a computer, tablet, etc.) can be used to transmit signals to, and receive signals from, the one or more objects of interest.

A device includes but is not limited to portable and handheld electronic devices, small standalone units in communication with other electronics whose main function is to provide radar functionality at remote locations, stationary electronic devices, and larger environment devices such as a smart room or a smart whiteboard, for example.

Radar-based object tracking systems can enable two-dimensional or three-dimensional object position and gesture determinations of an object of interest moving on a surface or in free space.

In addition, if multiple objects of interest employ delay elements with unique delays, multiple objects of interest can be simultaneously tracked by the plurality of radars in the object tracking system, allowing for improved collaborative experiences.

For example, such systems can allow multiple users in the same meeting room, each having a stylus, to collectively edit, draw or otherwise contribute ideas to a shared document being created or displayed on a device such as a smart board or smart display.

In another example, wearable devices such as gloves outfitted with a delay element on one or more fingertips can provide one or more objects of interest (each fingertip with a delay element being an object of interest) for performing gestures.

Apple's patent FIG. 4 above illustrates MacBook #400 utilized within a radar-based object tracking system. The MacBook  includes three radars #402, and stylus/Apple Pencil #404 positioned on a surface of the MacBook. To track the position of Apple Pencil, each radar can transmit a signal at a certain frequency and measure its distance to the tip of the Apple Pencil (e.g., R1, R2 and R3, respectively) using reflections from the Pencil tip. Triangulation algorithms (e.g., systems of equations) can then be applied to the measured distances to determine the location of the stylus tip.

For full details, review granted patent 11946996.