By Alessandro Vinco & Brian Condell
This fourth blog in the Data Capture series looks at Time of Flight (ToF) and how it is disrupting the logistics industry. For many years objects and parcels have been measured mostly by human operators with measuring tapes or by very expensive fixed Lidar sensing systems. Both methods have clear advantages:
However, both methods show significant pitfalls: measuring tapes are only as fast and accurate as their operators, while fixed lidar machines are expensive and only available in very few selected locations. Moreover, both methods significantly slow down both the supply chain and distribution of goods.
When objects are not correctly measured packaging is often wasted with much larger boxes than needed and delivery vans that are often traveling at a much lower storage capacity because of oversized boxes! Measuring objects, parcels, and pallets could greatly scale and improve with a technology that is widely available, accurate, and low-cost: that’s where the time of flights comes into play.
Time of Flight (ToF) is the technology that measures the time it takes a light pulse to travel from the light source onto an object and bounce back into the source. The time measured by the system then provides a measure of the distance between the source and the object since the speed of light is constant. The principle is shown in Figure 1 below:
Figure 1: Time of flight system overview
Similar to single-point scanning lidar technology, in a ToF sensor light from the laser source first goes through a diffuser that increases the width of the light beam, thus illuminating a wide surrounding area. Also, the CMOS sensor capturing the reflected light is made of multiple pixels, each capable of measuring the time it took light to bounce off the object and travel to the sensor. This allows a ToF sensor to deliver a multi-pixel 3D “picture” in one snapshot, without any moving parts.
ADI’s latest addition to the family of ToF sensors is the ADTF3175 module: a 1 MPixel CMOS sensor with integrated illumination, optics, and power management (Figure 2). The module has been tested with companion software algorithms to demonstrate the ability to dimension objects with high accuracy.
Figure 2: ADTF3175 time of flight module has a compact form factor
The low power and small form factor together with the high-performance 3D CMOS sensor make ADI’s Time of Flight modules highly portable for object and parcel dimensioning use cases, enabling a completely new class of applications (Figure 3).
Figure 3: Box dimensioning with the ADTF3175 demonstrator (left) and related used interface (right)
The advantages of time of flight don’t stop here: if used in multi-sensor systems with synchronized 3D depth cameras ToF also enables dimensioning of much wider and more complex objects when paired with suitable machine vision algorithms, opening new paths to highly accurate measuring systems at a fraction of the cost of fixed lidar scanning devices. When lidar scanning systems are not available and measuring tapes have a hard time providing accurate results on wide pallets and irregular shapes, time of flight becomes an obvious choice. Pallets and stacks of objects are now measured in seconds with the ADTF3175, wherever needed (Figure 4).
Figure 4: Image stitching algorithms enable complex object and pallet dimensioning applications using time of flight
The dimensions of billions of parcels are measured each day while transiting through warehouses, trucks, and couriers’ hands. ADI brings real-time parcel and object dimensioning onto the field with the ADTF3175 1 Megapixel time of flight module: no more bottlenecks along the supply chain, no more wasted packaging with oversized boxes, and improved sustainability for delivery vans that travel at their true full capacity. So now hopefully you can appreciate what ToF can bring to logistics in the form of enhanced perception, optimized classification, increased productivity, and reduced labor costs.
Find the fifth blog in this series here.