What Is a Time of Flight Sensor (ToF)?

The time of flight sensor (ToF) has a peculiar name. It doesn’t necessarily mean it will calculate the time a flying object is in the air, nor does it measure the precise time an object takes off from the ground. Before understanding what a ToF sensor does, it’s essential to understand what ToF actually is. ToF measures the time it takes for a physical object to travel a given distance through a medium. Typically, this measurement can determine velocity and path length, but it can also be used to learn about an object’s dimensions.

A Time of Flight sensor can use all the information gained using ToF principles for applications such as robot movement, human-machine interfaces, – like the second-generation Kinect sensor for the Xbox One – smartphone cameras, machine vision, and even Earth topography. While all these uses aren’t exactly the same, the information provided can serve all their purposes. Now that we’ve established what a ToF sensor can do, it’s equally important to determine what they consist of, how they generate the information, and, finally what specific purposes this information can serve for in the world of robotics.

How a ToF sensor works with light reflections. Image via Wikipedia

What Makes Up a ToF Sensor?

From a general perspective, a ToF sensor isn’t a device that requires decades of research to understand. It’ll consist of a few parts but none of them are particularly obscure or hard to piece together.

The first part is the lens, which, given that it’s essentially a camera, is pretty easy to understand. The lens itself, like any other camera, gathers the reflected light since it cannot produce any light by itself nor can it acquire depth signal from ambient light. According to a scientific study by Subhash Chandra Sadhu for Texas Instruments, ToF cameras have “have special requirements to be met with while selecting or designing the lenses.” While the rest of the study goes on to explain the specifics (which he explains very well), it’s important to understand these limitations if you want to fabricate your own ToF sensors in the future.

An example of a ToF sensor. Image via Quality Magazine

Also included in the ToF camera package is the integrated light source that keeps the seen, well, lit. Considering that all the light must come from the sensor, it’s equally important to make sure that no outside sources of light – like sunlight – disrupt the image intake.

Then there’s the image sensor, the centerpiece of the ToF camera. The sensor does the heavy lifting, storing all capture image information, including the time it takes for the light to travel from the integrated light source to the object and then back.

Finally, there’s the interface, which shows the data captured. It’s the less showy aspect of the ToF, but, hey, it’s still essential!

How Does a Time of Flight Sensor Work?

The Time of Flight sensor is able to capture depth information for every pixel in the image captured. It is mainly used for machine vision applications and advantages include the sensor’s compact construction, its relative ease-of-use, a precise accuracy of approximately 1cm, and high frame rates.

There are 2 principle ways in which a ToF sensor can determine distance and depth.

The first is is a ToF sensor based on light pusled sources. This form will measure the time it takes for a light pulse to travel to from the emitter to the scene and then back. Once everything has been measured and taken, through the magic of mathematics and algorithms, the distance and depth of all the objects captured by the sensor are calculated and determined.

At Seeed Studio, they mocked up a graphic that simply yet accurately depicts how the process works.

Easy enough, right?

This graphic explains more clearly how the light refracts from the object back to the sensor and how that measures the distance from each relevant point. Image via Seeed Studio.

The second way is a ToF based on continuous waves which detects the phase shift of reflected light. The modulating amplitude creates a light source inm a sinusoidal form with a known frequency.The detector then determines the phase shift (a shift when the graph of the sine and cosine functions shift left or right from their standard position) of reflected light.

Once this process happens, more math happens as well, determining the distance and depth of all the objects captured by the sensor.

 While the end results of both methods are similar, their journeys differ. The illumination of the entire scene, regardless of the method, will make it possible to determine the distance and depth of each object scanned by the sensor – all in a single shot.
The result? A range map in which the pixels encode the distance to each point on the captured scene.
Over at Melexis, they showed a depth image of a man in a car. The colors are represented as follows:
– The blue sections indicate that the point(s) is(are) far away
– A red section indicates closer proximity to the sensor
Image via Melexis.

The Advantages and Limitations of the Time of Flight Sensors

Like any set of technological tools, there are upsides and downsides.


Some of the clear advantages of using ToF sensors for 3D measurements are the following:

  1. Higher resolution captures.
  2. Real-time capabilities – no need to wait days for a result.
  3. Works in low light conditions – even no light is possible.
  4. The costs aren’t particularly high.
On the other hand, its limitations are worth considering, just in case your needs aren’t lined up with what a ToF sensor can do. They are as follows:
  1. The presence of scattered light due to unwanted reflections.
  2. External bright surfaces that are close to the camera can quickly scatter too much light into the lens, creating artifacts.
  3. ToF distance measurement requires light that has been reflected just once.
  4. If a light has been reflected multiple times, it can lead to the distorting of the measurements. These multiple reflections are usually caused by corners and concave shapes.
  5. Ambient light and sunlight make it more difficult to capture outdoors (sunlight causes the saturation of sensor pixels)

In What Manufacturing Contexts Can You Use ToF Sensors?

ToF sensors are highly practical in numerous applications including logistics, factory automation, and autonomous robotics and vehicles.

For logistics, ToF sensors can help guide robotic arms for packaging assistance, box filling, stacking, volume scanning, and labelling. A pick-and-place case study conducted by Lucid at Pensur, an engineering company, looked into how their 3D vision systems allowed for a far more efficient process and freed up valuable time for employees who were stuck doing the menial job day-in-and-out.

In the context of factory automation, ToF sensors can guide robots to find and pick up objects and place them where they need to be. Think of a car assembly. Nothing changes from car to car, but the ToF sensors will point out where everything is and everywhere they need to be.

ToF sensors can also be used in the context of maritime navigation in that the sensors can use AI-based object recognition. This is done to increase security on boats during sailing by detecting objects that may conflict with the ship’s path such as fishing boats, buoys, and debris, which can’t be detected by using only the ship’s radar.

IDenTV showed a brief example on their YouTube page of how these cameras can work and how quickly they can detect objects even at far distances.

Finally, for autonomous robots, a ToF sensor can help a robot plan and execute a task all on its own. Whether those processes consist of sanding, powder coating, or batch painting, the ToF sensor can help the robot understand each object’s specific dimensions and, with the help of the right software, can execute each task necessary by knowing where to start and stop.

ToF sensors are at the core of AutonomyOS™ and AutonomyStudio™. They are key to the first step: 3D perception, helping autonomous robots figure out what they need to do in real-time. Contact us today for more information.

4 Key Takeaways From FABTECH 2022

FABTECH has once again come and gone and this year’s rendition offered, for the first time since the pandemic, a chance to see everyone’s faces again. With hundreds of companies and tens of thousands of exhibitors and attendees alike roaming around in the Georgia World Congress Center, there was a diverse set of robots, machines, and approaches to manufacturing automation. But what stood out the most?

During our one-week stay in Atlanta, we had enough time to not only talk to some fascinating manufacturers but to peruse the rest of FABTECH to see who and what caught our attention. Here are our 4 biggest takeaways from FABTECH 2022:

An Abundance of Cobot Welding

FABTECH is known for the wide variety of exhibitors showing off new machinery, robots, and software but sometimes, you’ll find several companies displaying the same thing with different bells and whistles. This year, we saw a high number of cobot welders (and welding-adjacent exhibitors too) and counted a total of 37 of them across the three exhibit halls. 

Based on the number of people who came to our booth and asked us about lot-size-one welding solutions (it’ll come!), we can definitely understand the need for new welding solutions, with an average age for welders topping 55 and little helping seeming to be on the way. After all, we listed recurring problems in welding and how to solve them, but current solutions are still mostly suited for higher volume weldments not necessarily the futureproof way of enhancing this process – although they do play their part.

There are always new easy-teach tools being released with the goal of producing consistent high-quality welds, but even with these new additions, the cycle time challenges will continue to persist. Specifically, with lower volume productions, some of the challenges such as teaching and repeatable fixturing remain constant. While they make the end result better, the road to it doesn’t get much easier. Despite this, the demand at FABTECH for autonomous welding solutions shows just how much pain still exists in that world. It is abundantly clear that people are looking for small, low-cost solutions with a willingness to “figure things out” if it does not address each and every requirement in their production process. 

Subscriptions: A Path to Being Recession-Proof?

Every manufacturer, machine builder, and integrator knows how difficult it can be to keep up with a recession. With cash becoming more of a luxury during tough economic times, how do you continue to improve productivity when keeping staff becomes increasingly strenuous? How do you justify spending on robotics solutions when most of them come at a high initial cost all while needing operators?

Instead of investing hundreds of thousands (or more) all at once on integrating a high-mix solution, subscriptions to software-based solutions will lessen the burden of spending all that cash in one spot. With a subscription, it’s clear that you won’t own the software you’re using to solve your problems. What it will do, however, is spread out your bill over monthly or yearly periods. If a subscription consists of an hourly rate far below that of skilled labor burden rates, then suddenly the cost to finish a process becomes more palatable and sustainable for manufacturers looking to save costs and maximize efficiency – and you finally get systems that can address an indefinite variation of parts, which cannot be addressed with traditional robotics today. 

Naturally, there may be exceptions, but very few. Companies that function primarily on liquid cash – a rarity for most – won’t see their cash flow optimized by subscriptions. A company with a usage-based subscription can go up and down on operating expenses and they can shift their usage based on market conditions. 

Subscriptions offer “recession-proofing” because your operational expense can fluctuate with demand, instead of capitalizing highly complex integrations where the payback may not be realized if a recession happens earlier than expected. This kind of whiplash is still what the industrial sector still suffers the most from, despite every other sector having become more agile through flexible payment models. Even if you pay more in the long run, you can not only get more value and a solution that grows to meet more needs – you can also pay less when you need to, a critical feature when urgent cost cutting is required.

Subscriptions are surefire ways of making sure your processes can continue in spite of an economic downturn. By effectively managing recurring payments and enabling more stability and consistency in your skilled labor force (read: more productive labor, less lay-offs), then you can rest easy knowing that you’ll be able to hold the fort during tough times. 

Labor Shortages For All?

The two words that came up the most during FABTECH were “labor shortages.” Of course, this isn’t surprising. Since the start of the pandemic, it’s been especially difficult to replace skilled workers performing manual labor. Now that we’re further removed from the pandemic as ever, manufacturers need the same level of productivity they had prior to 2020.

In theory, people want their cycle times to be as close to zero as possible. Granted, no action will ever be instantaneous, but the more we lessen cycle times, the more efficient everyone will be. If manufacturers add robotic or automation solutions to their setups, they need these new solutions to be efficient. If an automation solution is complex and adds more work to the operators, then what kind of time are you actually saving? 

By switching to smaller, simpler, more modular, and mobile solutions – machines that can function with infrequent or limited oversight from operators – the incremental cost of using your capital will be significantly stabilized, maximizing the speed with which you can get an outstanding payback. As well, by freeing up the operator’s time, they can move on to other tasks that require human input in a different way. Essentially, they can solve more with less.

Skilled Labor, On-Demand: The Power of AutonomyOS™

Though the above points vary in nature, they all share some sort of connection. After all, manufacturers, while they all differ in their work – all face similar problems. Labor shortages, market saturation, and money management can make or break a company. To find a solution that can tackle all these problems, it might benefit your company to take a look at AutonomyOS™, a software that can essentially act as skilled labor on-demand. 

At our booth, we saw several people ask us about processes we expect to support in the future. Our sanding solution with DIY Robotics was well understood from the jump, with manufacturers grasping how the process works quite easily. There is an abundantly clear need for autonomy as a solution to shortages of all kinds.

With AutonomyOS™, you can say goodbye to having skilled workers working around the clock to finish a list of items to be powder coated, sanded and – in the future – deburred, welded or more. Thanks to a OpEx-friendly subscription, and a wide array of ready-to-go processes, all manufacturers will need to do is press a button to have their skilled robots do the tough work (just like the sanding solution at our booth!). It is quite literally skilled labor, on-demand: use what you need and pay accordingly. With the ability to have robots and cobots alike perform tasks without the need for intricate setups by operators, you can unlock productivity at faster rates than ever before.

The advantage of our hourly model – where you only pay for your software subscription in operation – means that you can stick to minimum commitments and add usage through a token system. This overflow can help you manage the ups and downs of production utilization, but also help maximize the utilization and Overall Equipment Effectiveness (OEE) of all the other equipment you’ve capitalized in your facility. 

At the same time, we don’t make you rent equipment – you can still buy that yourself, finance or rent through a third party – but the autonomy which makes it so powerful for high-mix manufacturers is available on-demand and works flexibly to help you meet your growing needs.

The best part? The more you use it, the faster your payback on your entire robotic system.

Industrial Space Continues to Grow and Adapt

The combination of reshoring, labor shortages, and financial uncertainty are forcing everybody to get lean and efficient – fast. This doesn’t mean big massive system integrations – small becomes beautiful. This also means simplicity, minimal training and high-speed payback are essential.

Transformative technology is the only way to do this – old models simply will not do. While many were not at FABTECH and busy minding the store at home, so many more at the show were truly ready for new ideas, new modes of production, and new ways of doing business, because they feel the pain the most. We know many may have stumbled a few times or more in their journey through automation, but fortunately, autonomy is here for you today.

With an AutonomyOS™-enabled robotic machine, you can say goodbye to labor shortages and maximize your efficiency. With the ability to set up behaviors to execute tasks such as paint spraying, sanding, welding, and more, you’ll find all the flexibility you want for your manufacturing needs. Contact us to learn more