Corvus Robotics’ Autonomous Drones Tackle Warehouses

Flying robots can do warehouse inventory way faster than humans

5 min read
Drone flying in a warehouse

Corvus' warehouse inventory tracking system involves autonomous drones that can fly unattended for weeks on end.

Corvus Robotics

Warehouses offer all kinds of opportunities for robots. Semi-structured controlled environments, lots of repetitive tasks, and humans that would almost universally rather be somewhere else. Robots have been doing great at taking over jobs that involve moving stuff from one place to another, but there are all kinds of other things that have to happen to keep warehouses operating efficiently.

Corvus Robotics, a YC-backed startup that's just coming out of stealth, has decided that they want to go after warehouse inventory tracking. That is, making sure that a warehouse knows exactly what's inside of it and where. This is a more complicated task than it seems like it should be, and not just any robot is able to do it. Corvus' solution involves autonomous drones that can fly unattended for weeks on end, collecting inventory data without any human intervention at all.



Many warehouses have a dedicated team of humans whose job is to wander around the warehouse scanning stuff to maintain an up to date list of where everything is, a task which is both very important and very boring. As it turns out, autonomous drones can scan up to ten times faster than humans—Corvus Robotics' drones are able to inventory an entire warehouse on a rolling basis in just a couple days, while it would take a human team weeks to do the same task.

Inventory is a significant opportunity for robotics, and we've seen a bunch of different attempts at doing inventory in places like supermarkets, but warehouses are different. Warehouses can be huge, in every dimension, meaning that the kinds of robots that can make supermarket inventory work just won't cut it in a warehouse environment for the simple reason that they can't see inventory stacked on shelves all the way to the ceiling, which can be over 20m high. And this is why the drone form factor, while novel, actually offers a uniquely useful solution.

It's probably fair to think of a warehouse as a semi-structured environment, with emphasis on the "semi." At the beginning of a deployment, Corvus will generate one map of the operating area that includes both geometric and semantic information. After that, the drones will autonomously update that map with each flight throughout their entire lifetimes. There are walls and ceilings that don't move, along with large shelving units that are mostly stationary, but those things aren't going to do your localization system any favors since they all look the same. And the stuff that does offer some uniqueness, like the items on those shelves, is changing all the time. "That's a huge problem for us," says Mohammed Kabir, Corvus Robotics' CTO. "Being able to do place recognition at the granularity that we need while everything is changing is really hard." If you were looking closely at the video, you may have spotted some fiducials (optical patterns placed in the environment that vision systems find easy to spot), but we're told that the video was shot in Corvus Robotics' development warehouse where those markers are used for ground truth testing.

In real deployments, fiducials (or anything else) isn't necessary. The drone has its charging dock, and the initial map, but otherwise it's doing onboard visual-inertial SLAM (simultaneous localization and mapping), dense volumetric mapping, and motion planning with its 10 camera array and an autonomy stack running on ROS and PX4 for real time flight control. Corvus isn't willing to let us in on all of their secrets, but they did tell us that they incorporate some of the structured components of the environment into their SLAM solution, as well as some things are semi-static—that is, things that are unlikely to change over the duration of a single flight, helping the drone with loop closure.

One of the big parts of being able to do this is the ability to localize in very large, unstructured environments where things are constantly changing without having to rely on external infrastructure. For example, a WiFi connection back to our base station is not guaranteed, so everything needs to run on-board the drone, which is a non-trivial task. It's essentially all of the compute of a self-driving car, compressed into the drone. -Mohammed Kabir

Corvus is able to scan between 200 and 400 pallet positions per hour per drone, inclusive of recharge time. At ground level, this is probably about equivalent in speed to a human (although more sustainable). But as you start looking at inventory higher off the ground, the drone maintains a constant scan rate, while for a human, it gets exponentially harder, involving things like strapping yourself to a forklift. And of course the majority of the items in a high warehouse are not at ground level, because ground level only covers a tier or two of a space that may soar to 20 meters. Overall, Corvus says that they can do inventory up to 10x faster than a human.

With a few exceptions, it's unlikely that most warehouses are going to be able to go human-free in the foreseeable future, meaning that any time you talk about robot autonomy, you also have to talk about safety. "We can operate when no one's around, so our customers often schedule the drones during the third shift when the warehouse is dark," says Mohammed Kabir. "There are also customers who want us to operate around people, which initially terrified us, because interacting with humans can be quite tricky. But over the last couple years, we've built safety systems to be able to deal with that." In addition to the collision avoidance that comes with the 360 degree vision system that the drone uses to navigate, it has a variety of safety-first behaviors all the way up to searching for clear flat spots to land in the event of an emergency. But it sounds like the primary way that Corvus tries to maintain safety is by keeping drones and humans as separate as possible, which may involve process changes for the warehouse, explains Corvus Robotics CEO Jackie Wu. "If you see a drone in an aisle, just don't go in until it's done."

We also asked Wu about what exactly he means when he calls the Corvus Robotics' drone "fully autonomous," because depending on who you ask (and what kind of robot and task you're talking about), full autonomy can mean a lot of different things.

For us, full autonomy means continuous end to end operation with no human in the loop within a certain scenario or environment. Obviously, it's not level five autonomy, because nobody is doing level five, which would take some kind of generalized intelligence that can fly anywhere. But, for level four, for the warehouse interior, the drones fly on scheduled missions, intelligently find objects of interest while avoiding collisions, come back to land, recharge and share that data, all without anybody touching them. And we're able to do this repeatedly, without external localization infrastructure. -Jackie Wu

As tempting as it is, we're not going to get into the weeds here about what exactly constitutes "full autonomy" in the context of drones. Well, okay, maybe we'll get into the weeds a little bit, just to say that being able to repeatedly do a useful task end-to-end without a human in the loop seems close enough to whatever your definition of full autonomy is that it's probably a fair term to apply here. Are there other drones that are arguably more autonomous, in the sense that they require even less structure in the environment? Sure. Are those same drones arguably less autonomous because they don't autonomously recharge? Probably. Corvus Robotics' perspective that the ability to run a drone autonomously for weeks at a time is a more important component of autonomy is perfectly valid considering their use case, but I think we're at the point where "full autonomy" at this level is becoming domain-specific enough to make direct comparisons difficult and maybe not all that useful.

Corvus has just recently come out of stealth, and they're currently working on pilot projects with a handful of Global 2000 companies.

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
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A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay
Blue

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.

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