An introduction to building Time-of-Flight sensor arrays for collision avoidance systems in mobile robots
Mobile robots are already widely used for transportation, logistics, manufacturing and inspection tasks. Mobile robots are here to stay and avoiding them could leave your organization at a significant disadvantage compared to your competitors. 1,2
Mobile Robots Need to Move Quickly and Accurately
Anti-collision systems aren’t just for indoor ground robots. Drones also need to avoid any objects they may encounter while flying, like branches, buildings, and even other drones. For drones that inspect facilities and infrastructure, drone collision avoidance systems can help prevent the drone from crashing into the object it is examining.3
Laser technologies are very effective for mobile robot obstacle avoidance but they can pose a risk to eyesight. Some drones use rotating LIDAR anti-collision systems, but the moving parts in these systems mean they are more prone to failure, resulting in costly repairs.1-3
Time-of-Flight Sensors Provide a Complementary Anti-Collision System
ToF sensor modules use beams of light to detect obstacles. This means that a single module only provides limited coverage, but we can significantly increase coverage using careful placement of multiple sensors, which is a cost-effective option to check for obstacles above or below the 2D laser scanner’s coverage.
With careful sensor placement, ToF multi directional arrays can provide a simple obstacle detection system compared with existing 3D technologies, while consuming less energy and coming in at a fraction of the price. What’s more, using multiple ToF sensor modules provides a complementary system, covering blind spots left by the main anti-collision system. Having multiple beams pointed in different directions allows the user to scan the ground for small obstacles below the laser’s field of view or detect objects above its field of view that could collide with the robot’s chassis or payload.
Furthermore, ToF solutions that use infrared light, such as those from Terabee, are eye-safe and work in all indoor lighting conditions.
In the image below, you will see two versions of anti-collision systems. Right: Example of object detection using TeraRanger sensor arrays. Left: Anti-collision system using a laser scanner.
Building Your Perfect ToF Sensor Array for Your Anti-Collision System
ToF Sensor Arrays for Drones
The TeraRanger Tower Evo does not rely on moving parts to provide complete coverage, so it is not prone to failure like a rotating system. What’s more, it is lightweight (132g), so you can minimize battery drain and maximize flight times. The system is modular, and you can choose between 4 or 8 sensors depending on your needs.7
TeraBee Have a Cost-Effective Solution for Every Robot
References and Further Reading
2. ‘Introduction to Autonomous Mobile Robots’ — Siegwart R, Nourbakhsh IR, Scaramuzza D, MIT Press, 2011.
3. ‘Drone Collision Avoidance for Beginners’
4. ‘Time-of-flight principle’
5. ‘TeraRanger Hub Evo’
6. TeraRanger Multiflex
7. TeraRanger Tower Evo