IEEE Power Electronics Magazine - March 2017 - 27

(a)

(b)

FIG 4 (a) A self-driving car with lidar (photo courtesy of Wikimedia) and (b) its view of the world (image courtesy of Mapping
Ignorance).

efficiently, and expediently. This map requires raw data
that, in the case of a human driver, are acquired primarily
through the eyes. For an autonomous driving computer,
lidar is the ideal method to acquire these data, whether
day or night. Just as with human drivers, it operates in
conjunction with other sensors, such as radar, visual, and
ultrasonic systems, but lidar provides the most robust
and data efficient means of collecting high-resolution,
high-accuracy distance data.
The second key application is augmented reality.
Whereas virtual reality attempts to replace the surrounding world and convince the user that he or she is in an
environment different from his or her actual physical
environment, augmented reality enhances human senses
based on a combination of data provided by additional
sensors and possibly additional data created by people or
computer models, translated into a format that our senses
can perceive.
In modern form, the predominant vehicles for augmented reality are smartphone displays (think of the game
application Pokémon GO) or goggles that project additional
data into one's field of vision. Figure 5 shows an example of
the latter, the Microsoft Hololens, with Google Glass being
another prominent example. Today's computing power
allows one to project data in the form of images that can
be blended in with one's natural field of view. This technology has many far-reaching applications. While gaming is one
obvious use, there are many others. Imagine earthquake rescue workers who can have precarious rubble highlighted for
their safety, or the architect who can show clients his or her
vision of a major remodeling project, or the doctor who can
assist in a surgery on another side of the globe.
Since the majority of humans perceive a 3-D space, the
projection of additional imagery into this space requires
an accurate real-time 3-D map, the key strength of lidar.
While much can be done with processing of standard camera images, distances must be inferred based on one or
more images. For noncritical applications, this estimated

distance data may be adequate. Applications requiring
accurate long-range data, safety-critical applications,
or applications with less than optimal lighting use lidar
to provide direct measurement of unambiguous, highresolution data.

What About Power Electronics?
One might ask, what does lidar have to do with power
electronics, and why is it appearing in this magazine? The
fact is that electronics and photonics have had a close
relationship since the beginnings of electrical science [9].
For power electronics and lidar, the primary relationship
revolves around the light source and its driver. This system is essentially a pulse-power system, and its proper
design requires fast power devices, high-current gate
drives, understanding and control of power loop parasitics, high-speed current sensing, and many other topics
critical to power electronics. This will be discussed later
in this article, but first we need to understand some basic
lidar concepts.

How Does Lidar Work?
Much like its verbal forerunner, radar, the word lidar
originated as an acronym derived from light detection

FIG 5 The Microsoft Hololens augmented reality goggles.
(Photo courtesy of Microsoft.)

March 2017

z IEEE PowEr ElEctronIcs MagazInE

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - March 2017