We explain how to design and build autonomous indoor drones and what indoor positioning systems to use to track indoor drones when they are not autonomous.
Though we focus on indoor drones and autonomous drone indoor navigation, the drone positioning system works perfectly well outdoors. It just requires outdoor-protected beacons, for example, Super-Beacons-Outdoor.
When you are new to the Marvelmind Indoor “GPS” system and are unsure what to choose, get the Starter Set Super-MP (MP stands for multi-purpose), which (MP stands for multi-purpose), and that would be your safest choice.
For more specifics, study the recommended options below.
Overall the best and safest choice when you are not sure what to choose or what exact experiments you will run, but you want to simultaneously have the greatest flexibility and performance.
It is the best choice when you need to connect to PixHawk because two pins for the connection to PixHawk are readily available on the Super-Beacon. See more.
The set is designed for micro-drones (<100g) because the Mini-TX mobile beacon is tiny and light. It is easily 15-20m, sufficient for most real cases. The set can also be used for larger drones, but the ultrasound range Mini-TX is smaller than that of Super-Beacons or Beacons HW v4.9.
Mini-TX is excellent for tracking. The new version of Mini-TX-2 is also ideal for connecting to PixHawk because it has a special 6-pin connector with two pins dedicated to PixHawk connectivity (TX + GND) – similar to those of the Super-Beacon. Notice that older Mini-TX – delivered in 2022 and earlier didn’t have the 6-pin connector on the bottom.
An advanced version of the “Starter Set Super-MP-3D + Super-Beacon – Location+Direction on the drone” option.
The Precise-Z, which physically consists of 2 additional stationary beacons, gives the possibility to have precise Z coordinates in all ranges of Z.
– Placement Manual – Precise-Z slide
– Video explanation about Z and placement of beacons
– https://marvelmind.com/product/super-beacon/ – additional stationary beacons for Precise-Z feature
If you are not sure, just send us an email to firstname.lastname@example.org with detailed questions and we will be happy to help and advise.
Marvelmind indoor positioning system or Marvelmind Indoor “GPS” is widely used for drones or quadcopters in many different ways:
The indoor positioning system for a small drone is not different from other indoor positioning systems, for example, for larger drones or any other 3D (XYZ) indoor positioning systems.
The only peculiarity is the weight of the mobile beacon (tag) installed on the drone. It is solved using a stripped-down version of Mini-TX: removing the shell, removing the battery, or replacing it with a very light battery.
Also, the smaller drones are usually dumb – they don’t have an onboard computer or autopilot, for example, PixHawk and similar. All intelligence comes from the ground station. But with that, there are exceptions.
Drone swarms and drone shows may include tens or even hundreds of drones. When they fly outdoors, RTK GPS does the job very well. But RTK GPS doesn’t work indoors.
Marvelmind Indoor “GPS” supports both PixHawk with ArduPilot and PX4:
Using a combination of Marvelmind Indoor “GPS” and PixHawk is the easiest and quickest way to fly indoors autonomously.
There are several but rather simple aspects that have to be taken into account to fly indoors successfully:
See the Products page for different starter set options.
Remember that just three stationary beacons would have little resiliency against obstructions for 3D (XYZ) tracking. Any occlusion of any stationary beacon – a non-line of sight/hearing situation – will lead to no tracking or erroneous tracking – like in GPS: “no satellites visibility = no GPS coordinates = no tracking”.
Thus, we recommend at least N+1 redundancy for stationary beacons. And that is why our starter sets for 3D consist of 4 stationary beacons.
Even better is to have 2N redundancy with fully overlapping 3D submaps. That would be either 3+3 or 4+4 stationary beacons. The system would automatically choose the best submap for tracking. That kind of system is very resilient, and with proper placement of the beacons, you can fly even in complex rooms with columns, for example, without tracking issues.
The key to excellent tracking is to provide proper coverage at any flight point, i.e., the mobile beacons on the drone must have three or more stationary beacons belonging to the same submap with a clear, direct line of sight/hearing within 30m.
The proper placement is usually the key and vital to drones because they require 3D; the drones are fast, and the mistakes may be particularly costly. What to pay attention to?
Tracking one indoor drone in one large open space is very easy. With a Starter Set Super-MP or Starter Set NIA-SmallDrone, the precise 3D tracking system can be set in 10-15 minutes, including unpacking and software updates to a set that just was received. If you have made all initial software updates prior to the setup, the system can be deployed in less than a minute.
Autonomous flight is a significantly more complex task because you need to precisely track a drone and integrate its autopilot with the drone/chassis, which is typically made from different parts (chassis, motors, motor drivers, telemetry, remote control). And on top of this, the autopilot must be integrated with the indoor positioning system as described above.
If autonomous flight by a single drone is a challenging task, then autonomous flight by a swarm of drones is the pinnacle of this complexity pyramid. It is even more challenging but still doable if you do it one step at a time.
Before we deeply submerge into the indoor drone swarms, let’s answer the basic question: “How are those thousands of drones flying in the sky?” – well, it is straightforward – they use the RTK GPS positioning system. But, remember, the RTK GPS relies on GPS. If there is no GPS, there is no RTK GPS either. Thus, as soon as we move indoors or other GNSS-denied areas, forget about the GPS (GLONASS, Beidou, Galileo, etc.)
Having a massive swarm of small drones and playing a nice show would be great. However:
If drones are too big:
In many cases, it is possible to set the autonomous flight by multiple drones so that they are not even aware that there are other drones around. They believe they are so unique and so exceptional. It is in your interest to keep them in this naive belief because it is the simplest way to make drone swarms.
Using a combination of solutions, it is possible to fly a swarm of drones using IA: Indoor positioning system for drone shows and swarms.
This complex solution may not be suitable if you are new to our system or drones in general. But it offers the best performance for indoor drone shows because it allows flying multiple autonomous drones without the location update rate reduction and offering the highest ±2cm positioning accuracy.
As discussed above, the first thing to decide is whether you need direction based on the Paired Beacons. If you need, then you need two mobile beacons per drone. If you don’t need it, only one mobile beacon per drone.
It is possible to fly with a single mobile beacon, but the SW on the autopilot must be more complex – not out of the box because it shall provide the direction and correction of the drone’s gyro’s drift while it is flying. It is complex. Doable. But complex. And if only possible, we always recommend the Paired Beacons configuration as an easy solution for indoor direction, even in static.
However, as discussed above, for swarm drones or indoor drone shows, it may not be the best option. Thus, we will assume a more complex and fragile option based on a single mobile beacon as a drone’s main variant.
If your drones are tiny and cannot carry a 27g load (a stripped-down version of the Super-Beacon), then the Mini-TX without additional battery and housing is your best choice. In the stripped configuration, it is just 6.7g.
However, the Mini-TX works only on one frequency (31kHz). Thus, only NIA remains your option. Therefore, if you have ten drones, the location update rate per drone will be 1/10 of the system location update rate. For a small submap of 5x5m, it is possible to get 20-25Hz per system. Thus, per drone, the location update rate will be ~2-2.5Hz. This location update rate is suitable for slow-moving shows. But still, it is much better than nothing.
UWB-based indoor drone positioning systems don’t differ much in principle from the Marvelmind Indoor “GPS”. Of course, the underlying technology is different (time of flight of UWB compared to the time of flight of ultrasound). But the architecture and the network elements are very similar.
Practical differences between UWB and Marvelmind Indoor “GPS”:
Becomes more and more popular due to potential simplicity:
Consider an alternative: Autonomous drone landing pad.
Very impressive drone shows lead us to believe that drones are so intelligent. However, the view is very deceiving. The positioning system is a pearl of the setup – not the drones. Drones are rather dumb. They are not even aware that they are tracked. Besides, they are entirely remotely controlled based on the location data from the tracking system. Thus, they are even dumber. But it is okay. It doesn’t matter how the feat is achieved as soon as the performance is impressive and truly impressive.
Motion capture-based systems:
The minimum configuration for the drone tracking would be any NIA set with 3D capability. For example, three stationary beacons + 1 mobile beacon + 1 modem and Non-Inverse Architecture (NIA) or Multi-Frequency NIA (MF NIA) would already be OK for the drone.
Using drones for warehouse inspection is pretty popular – finding lost pallets, security, etc. Yes, it is a doable task but very complex in practice:
Nevertheless, the solution is up-and-coming. Thus, drone builders or builders of warehouse systems use our indoor positioning system for such solutions. In the video, we explain the peculiarities of the environment (narrow aisles and high shelves), how the peculiarities affect accuracy, and how to build the system optimally.
It is possible to build an autonomous landing platform for a drone. It can even be a moving one:
Drone flies using regular RTK GPS or even GPS when it is far and up to 30m from the platform. It is locked to the Indoor “GPS” coordinates and is landing based on these coordinates. As mentioned, the platform may be static against the Earth or moving. It doesn’t matter for the drone. So, you can precisely land on a moving vehicle, for example.