Industrial autonomous robots are redefining efficiency, productivity, and automation in the world of manufacturing and industrial warehousing. These robots have increased productivity and quality in industrial processes nearly overnight, but the technology that powers them has been developed over nearly a century.
This article examines some of the key sensor technologies that now allow industrial robots to function seamlessly.
Radar Technology in Industrial Robotics
Radar technology was secretly developed for military use leading up to World War II, and the term ‘radar’ was coined in 1940 by the US Navy. The acronym stands for Radio Detection and Ranging. Radar transmits radio waves and receives a reflected radio signal of those waves that have been ‘bounced’ off of another object. To do this, radar utilizes large-wavelength radio signals. It’s capable of detecting objects larger than ~1 meter at distances ranging from 2 meters to several kilometers.
Given its relatively low resolution, radar sensors are only used in large-scale industrial robotics applications such as human, infrastructure, and vehicle detection. For example, when an autonomous industrial robot that moves parts from a storage warehouse to an assembly navigates the warehouse, radar sensors may be used to map large features such as warehouse racking, other autonomous robots, walls, and other large items.
Radar sensors require relatively low power consumption. They output relatively simple data streams, requiring limited computational requirements.
Proximity Sensors
Similarly to radar and its “call and response” technology, general proximity sensors output a signal and receive that signal once it is reflected back from an object, which is incredibly important for autonomous navigation in industrial and manufacturing settings. While these technologies may not provide the autonomous robot with 360-degree presence detection like radar does, they are able to detect object proximities at a much higher resolution than radar.
For example, the VL53L1X Time-of-Flight sensor utilizes state-of-the-art 940mm laser-ranging technology to provide accurate object detection and distance measurements at distances between 4cm and 360 cm, which could allow an autonomous robot to navigate narrow corridors or place manufacturing parts.
LIDAR Sensors
Many autonomous industrial robots are required to navigate three-dimensional spaces such as large warehouses and manufacturing production lines. Autonomous robots are commonly required to actively re-map a space to ensure flawless navigation.
LIDAR technology, which is fundamentally similar to radar, uses Light Detection and Ranging technology to detect the distance from a transmitter to a reflective point. Fundamentally, this technology could be thought of as a combination of the radar and proximity sensors previously mentioned. However, rather than consistently emitting a single signal, LIDAR systems emit millions of light points, sequentially, per second in a 360-degree field of view. This emission strategy allows each ‘point’ to be independently map-able, which can then be used to form a ‘point cloud’. A point cloud can be interpolated to create a meshed surface world that an autonomous robot can subsequently navigate.
These LIDAR point clouds are also fully measurable, meaning the vehicle instantaneously knows its relative distance to everything within the mesh environment. However, LIDAR systems require the use of compute-intensive AI neural networks for object classification, surface meshing, and self-driving in order to process LIDAR’s point cloud data. This can make LIDAR-based systems energy-demanding and capital investment-intensive.
As with all autonomous robots, LIDAR systems can mis-classify objects, cannot see object behind other objects, and often require astonishing amounts of training and configuration.
Thermal Cameras
Many manufacturing and industrial applications utilize dangerous processes and operate in dangerous environments. Naturally, industrial autonomous robots are most used in applications that could potentially harm a human worker. However, that implies that the autonomous robot itself is subject to harmful conditions.
To protect industrial and manufacturing autonomous robots in harmful environments, they utilize thermal cameras that can detect extreme temperatures of surfaces and objects. Thermal cameras are used to provide information about safe navigation routes by avoiding temperatures that may damage the electronics onboard, as well as provide information to the manufacturing or industrial facility that temperatures are outside of expected zones. Additionally, thermal imagers and cameras are used to detect if a human or other animal is present.
For example, if an autonomous robot using a LIDAR system for primary navigation is unable to ‘see’ and identify a human standing within a warehouse rack, a thermal camera can help detect the human’s presence and avoid potential collisions with the human.
Motor Control Sensors
Autonomous industrial robots are often used in manufacturing applications that require precision and accuracy. These robots perform specific tasks like moving many objects very quickly, moving large objects into very precise locations, or performing ultra-precise actions such as welding or applying adhesive more accurately than humans can. As such, the motor systems that control these robots are manufactured to very high tolerances, as their exact position must be known at all times. However, there are multiple ways to sense and control motors.
Stepper motors and server motors are capable of starting and stopping their rotation to and from assigned positions, making them very desirable for robotic arms and similar actuators. Servo motors are similar to stepper motors in that they start and stop their rotation at specified locations, but they are not as accurate (yet they are more efficient).
Both stepper motors and servo motors can utilize multiple types of motor control sensors such as optical encoders, electromechanical encoders, and hall effect sensors. Rotating motors, which spin a shaft around an access at variable speeds, rely on different sensor types to sense their speed. General motor speeds can be understood using current sensors, while other sensors such as optical encoders and hall effect sensors can also be used to count the number of rotations of a shaft.
Autonomous Industrial Robots Sensors
Autonomous industrial robots are essential to the operation and functionality of the facilities they are used in. Sensors play a massively important roll. Call-and-response sensor technology such as radar, LIDAR, and Time-of-Flight sensors are extremely useful for navigation, while thermal image sensors supplement robot navigation and protect the autonomous robot from hazards. Lastly, the variety of motor control systems and sensors such as encoders, hall effect sensors, and current sensors are essential to helping the autonomous industrial vehicle understand where it is and how it is operating in real-time.
For more information on important sensor technologies, be sure to check out our sensor category page or our Sensors Articles and Event page.
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