Obstacle Avoidance in DJI Drones (Explained for Beginners)


Many risks come with flying drones, and obstacles are one of those major sources of risk. This is because drones are naturally fragile and lightweight, thus making them prone to damage caused by impacts. This might lead to repairs that were unbudgeted for. Some of the obstacles can take you by surprise, and therefore avoiding them sometimes becomes tricky.

Almost all of the drones made by DJI have an obstacle avoidance system enabled by technologies such as infrared sensors, stereo vision sensors, ultrasonic sensors, and GPS. These sensors work together to make sure the drone detects and avoids obstacles in the flight path to prevent crashes. 

In this article, I will be discussing DJI drones and their impressive obstacle avoidance features. Get ready to learn all about what obstacle avoidance is, how it works and, its benefits. I’ll also take you through a list of DJI drones that don’t feature obstacle avoidance as well as those that have it. This is an ultimate read, and especially so if you love drones.

What is obstacle avoidance?

Obstacle avoidance is a safety feature found in more advanced drones, including many DJI drones. The feature enables drones to scan the environment and detect any obstacle along their route in real-time. Once your DJI aircraft detects the obstacle, it reacts immediately by avoiding it. 

This robotic feature is especially important in smaller drones since they don’t fly very high, and therefore they are at a higher risk of finding obstacles in their path. However, even many larger ones feature it. With obstacle avoidance technology, your drone will fly safely, and you can fly with confidence.

One of the main elements of obstacle avoidance technology is precision. It enables the drone to detect an obstacle from a few centimeters away and doesn’t require GPS to be aware of its surroundings. This means that your drone is provided with some positioning information even when it’s operating at high speed.

How does obstacle avoidance work?

Understanding how this technology works is essential before diving into the obstacle avoidance topic. Obstacle avoidance technology combines several technologies, all working together to enable the drone to avoid obstacles. Here are the technologies that make Collision avoidance possible.

  1. Sensor Fusion – This is fusing data from various sensors in one platform. It is done to establish something that a single sensor could not compute. Sensor fusion is also known as multi-sensory data fusion, and it’s a sub-branch of data fusion.

    This type of fusion is best applicable in drones that work with high precision. The combination of these sensors is to give data feedback to the flight controller responsible for algorithms and obstacle detection software.

  2. SLAM – Simultaneous Localization and Mapping is another critical aspect of obstacle avoidance technology. It’s not limited to the systems that are installed in aircraft alone. A drone maps its environment through SLAM and properly locates itself within the map.

    Nevertheless, the mapping doesn’t happen quickly. Once the SLAM builds a pre-existing map of surroundings in its memory, it refines it as your aircraft moves through the mapped area.

    Accuracy is one of the biggest challenges in this aspect. One must carefully and consistently take measurements while the drone is moving.

    Through its path, SLAM must record any noise made by the moving drone. Many obstacle avoidance technologies in most drones model incorporate SLAM, with monocular vision being one of those technologies.

  3. Obstacle Avoidance Algorithms – This is a process or guide that is followed by all the active sensors in data calculation to avoid obstacles. The algorithm is a set of step-by-step tutorials or formulas through which motor and stationary objects’ detection problems are solved. The effectiveness of the drones’ sensors and systems depends on the algorithm, and therefore, it must not be buggy or written poorly to avoid drone crashing or flight errors.

  4. Flight controller – This part is the one that receives any obstacle avoidance data, especially the detected objects. This comes after the sensors have scanned and mapped the surroundings, and from there, the flight controller controls the Collision avoidance algorithm.

    Depending on the data interpretation, the controller directs the drone to fly. The flight instructions can be flying above, below, stop or hover in front of the obstacle.

  5. Track and Follow Objects Sensors – These are sensors whose responsibility is to detect objects along the drone’s path. Interestingly, besides detecting objects, they are also made to detect vehicles, animals, people, among other things.

The combination of all these technologies creates a competitive obstacle avoidance system. Many drones can recognize and track several objects using this technology. You can also use the technologies to detect people, vehicles, animals, and other things in motion.

Our explanation of how obstacle avoidance works wouldn’t be complete without discussing the sensors used in obstacle avoidance. The sensors are many, but they are all not used ubiquitously by all drone manufacturers. Let’s look at the primary sensors to understand them better; here is a brief discussion of each of the sensors.

Types of obstacle avoidance sensors

  1. Ultrasonic sensor – These sensors are used for object detection, and they function by emitting a sound with high frequency. After that, the sensor monitors the time taken for the transmitted sound to echo back, to map the surroundings. There are two openings in these sensors; one is for sending out the sound with high frequency while the other is for receiving the echoed sound.

  2. Stereo Vision – These are the sensors that enable a drone to avoid an obstacle, and they function like the 3D sensing ability found in human vision. The results of this sensor are dependent on the number of corresponding pixels it identifies: the more pixels, the better the outcome.

  3. Time of Flight Sensors These are made of more components, unlike the other sensors, and are meant for collision avoidance. Some of the sensors’ elements include the lens, interface, sensor, and light source. This sensor can capture intense information for each image at the same time. Therefore, this means that it’s pretty fast and has high frame rates.

    The ability of these sensors to independently capture depth makes it easy for the drone to avoid obstacles. Another fact about these sensors is that they have accurate cameras. TOF sensors work by illuminating the whole area, not leaving any object out. They do this by using a pulse or a consistent wave light source and observing the reflected light.

  4. Infrared Obstacle detection sensor – This sensor uses the principle of infrared reflection. It’s this principle that helps it detect obstacles. The IR sensor comprises an infrared receiver, transmitter, and a potentiometer. The infrared ray will become weak according to the distance it spreads and finally vanishes. However, this happens if there is no obstacle. If there is an obstacle, the infrared ray will bounce back to the infrared receiver.

    Sometimes visible light can confuse the IR sensor, which can be prevented by using infrared detectors with specific infrared frequencies.

  5. LIDAR – This type of sensor detects objects and calculates their distance. They measure the time that a short pulse takes to travel from it to an object and back. It also calculates the distance from the light’s speed to establish any objects within.

What are the benefits of obstacle avoidance?

Now that we know what obstacle avoidance is and how it works, you may be wondering what it offers. There are many benefits of obstacle avoidance and why your drone needs it. Drones that have this technology boast many advantages. Here are some of the benefits of obstacle avoidance.

  1. Safety – This is the number one benefit of obstacle avoidance. No drone owner wants to imagine their drone crashing.  Everyone wishes to have their device back safely, but that doesn’t always happen. Sometimes you might lose concentration, causing the machine to hit an object and fly backward or to the side.

    On the other hand, if your drone has obstacle avoidance, it will not hit the object in the first place and risk crashing. This will also guarantee the safety of the people around where you are flying your drone.

  2. Confident flight – There’s a lot of stress that goes along with flying a drone if you are unsure of being able to fly it safely. However, with a drone that features obstacle avoidance, you can be at ease flying it and enjoy the flight. Whether flying a drone for commercial reasons or fun, obstacle avoidance will make a significant difference when your aircraft is aloft.

  3. Indoor Flying – Maybe you have heard about this or figured how it could be possible, but with the obstacle avoidance feature, your drone can fly indoors much more effectively. This is because the technology will help your drone navigate through tighter spaces while avoiding obstacles.

  4. Insurance costs – Insuring a drone for professional use is not cheap. You can be charged $50K for such drones, and that’s why it’s essential to avoid the high cost. Obstacle avoidance is one way of bringing down such insurance costs.

  5. Future drone parcel delivery – Drones are the future of deliveries, and soon they will be used to deliver medications, parcels, and other things to your door. For this to happen, several challenges must be overcome, and obstacle avoidance is a huge part of that. It will ensure that the drones are fit for delivery without risking anyone or anything.

Which DJI drones have obstacle avoidance?

Most present-day drones boast a slew of features, including sensors, algorithms, and high precision.  All these enable them to perform well in whichever application you engage them. However, a drone with an obstacle avoidance system is a cut above the average. It makes drone flights safer and more enjoyable. Here is a list of DJI drones that have an obstacle avoidance system.

Drone ModelObstacle Avoidance Features
DJI PHANTOM 4 PRO
A sensing technology of five directions comprising stereo vision and infrared sensors on the front, back, and sides and at the bottom.Active track intelligent mode including GLONASS and GPS positioning.
DJI Mavic 2 ProTopnotch sensing technology of infrared and stereo vision sensorsTwo front cameras are great in object tracking through trajectory projection.Two IR cameras at the bottom with infrared sensorsSide cameras for the prevention of sideway collisionsTwo back camerasAn infrared sensor at the top
DJI Inspire 2 Flight autonomyMultiple intelligent flight modesDownward vision system comprising of Ultrasonic sensor operating range and Ultrasonic sensor operating environment.Upward infrared sensor comprising of FOV, obstacle sensing range, and operating environment
Mavic 2 Zoom
Front and back obstacle avoidance technologyObstacle sensors on 6 sides
Mavic AirFront, bottom, rear collision avoidance detection sensorsFlight safety system
DJI Spark3D sense technology
DJI Air 2S Four-way obstacle avoidance system
DJI Mavic 3Omnidirectional obstacle avoidance

DJI Phantom 4 Pro

The DJI Phantom has obtained its name as one of the best drones for commercial photography. Its beautiful design and functionality make it a good investment. This drone has unmatched obstacle avoidance technology, despite the fact that it’s been around for a while. 

It boasts several sensors that can detect obstacles up to 10 feet away. The drone can sense objects in five directions simultaneously, and it features active track, smart flight modes, automatic home return, and other modes that make flying an incredible experience.

The five-direction obstacle avoidance system uses infrared and stereo vision sensing systems. The drone also boasts flight autonomy thanks to its intelligent data exchange, thus making it one of the best drone models with obstacle avoidance. Generally, this DJI drone has everything needed to perform its expected duties.

DJI Mavic 2 Pro

This is another drone model with an obstacle avoidance system that has dominated the market. You can trust this drone for unmatched and incredible performance. However, it’s a costly unit, and you will have to part with a good amount of money to own one.

One of the fantastic features of the drone is its high performance. Several features enable this, including a high-quality professional camera, intelligent flight modes, an obstacle avoidance system, and flight precision.

However, the most outstanding feature of this drone is its camera that has a shooting ability of 4K at 60 fps. The footage is not only stable but also of exceptional quality. Moreover, the drone can operate at a range of 8 kilometers from the controller. Besides, DJI Mavic can actively fly for half an hour, making it one of the longest flying consumer drones.

The Collision detection system of Mavic 2 Pro is enabled by infrared and vision sensors. These sensors ensure that the drone can detect obstacles from various directions, especially when there is sufficient light. However, its reaction to obstacles depends on your flight mode – the obstacle avoidance ability is switched off in sport mode.

DJI Inspire 2 

It would be an error not to mention the DJI Inspire drone as it’s one of the most popular professional drones. Many drone operators rate it as the best in filmmaking since its compatible with several professional cameras. 

Additionally, this drone avoids obstacles by using infrared and stereo sensors. Also, when combined with the ultrasonic sensor, it can detect objects that are 30 meters ahead of it and 1 meter above it. According to its manufacturers, the obstacle avoidance feature permits it to fly up to a speed of 34 miles per hour.

Which DJI drones do not have obstacle avoidance 

DJI Mavic Mini and Mini 2

This drone is one of the brand’s cheapest devices and one of the most compelling. It has powerful motors, which translates to a high speed and unmatchable performance in the wind. 

The DJI Mini and Mini 2 are the only DJI drones that don’t have an obstacle avoidance system. One of the reasons it lacks the system is its weight. This drone weighs 242 grams, just below the 250-gram weight limit requiring registration. If the obstacle avoidance system were added to the DJI Mini 2 drone, it would have put the weight over the 250 g limit.

Conclusion

Now you know what obstacle avoidance is, how it works, and the reasons why you should consider investing in drones with the technology. Also, we have reviewed the DJI drones that have obstacle avoidance systems and the one that doesn’t.  Consider safety as the number one reason you should own a DJI drone with obstacle avoidance technology.

Elizabeth Ciobanu

Editor-in-Chief. Elizabeth is a full-time (homeschooling!) mom of four, and serial entrepreneur in a variety of enterprises, one of which is producing content for Droneblog. If free time existed, she would love to spend more time on hobbies such as flying a drone.

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