Indoor positioning system technology
For autonomous robots, drones, forklifts, cranes, VR/AR, people, and other industrial applications
Indoor positioning systems have many flavors, and some are better suited for some applications than others.
Many fundamental technical aspects, from the line of sight to interference and basic radio coverage, must be considered when the system is being selected and deployed.
If any critical question that comes to your mind is not covered below or even incorrectly explained, please email us at info@marvelmind.com, and we will swiftly address it.
Executive Summary:
This page explains in detail the technology and special technical solutions behind indoor positioning systems and real-time locating systems.
- How large area can the RTLS cover?
- What is the range?
- How many tags can the system track?
- Trilateration vs. triangulation?
- What are interferences?
- Is it possible to use IPS outdoors?
- How do get direction or orientation?
- What are submaps?
- How to build submaps?
- What beacons to use outdoor?
- How to integrated with external systems?
- How to intergrate with PixHawk?
- How to intergrate with Arduino?
- How to intergrate with Raspberry Pi?
- How to intergrate with Nvidia Jetson?
- Why not to use SLAM?
- Are LIDARs good for positioning?
- How to get the highest location update rate?
- How to achieve the lowest latency?
- How to achieve the highest accuracy?
How large area can the RTLS cover?
There is no principle limitation on the area the indoor positioning or RTLS system can cover.
For example, Starter Set Super-MP can cover up to 1,000m2 of open space. With additional beacons, the area can grow and reaches tens of thousands of m2 until it doesn’t reach the capacity limit of a singe-modem architecture.
Adding another layer – Multi-Modem Architecture – raise the upper limit from 250 beacons to tens of thousands of beacons. Thus, the RTLS coverage can be really huge.
What is the range?
There are at least two types of ranges:
1) Range of ultrasound
2) Range of radio
Recommended maximum distance between beacons in a real industrial environment is up to 30 meters. It is defined by the ultrasound range.
However, this range can be smaller or larger:
– If there is little noise, it is pretty comfortable to track up to 50m
– If it is very noisy, the range may be as short as 10m or so
– With the help of the Horn, the range can be more than 100m
– Loud music or voice doesn’t necessarily produce ultrasound noise
– Some quiet machinery can produce loud ultrasound noise pollution
Using submaps, it is possible to build huge indoor maps – hundreds of meters in each direction. On such distances, radio range may become a limitation. A typical range for standard antennas is ~100m in open space, with full-size antennas – up to 400m.
It is possible to relatively easily extend the radio range to 1-2km, for example, in tunnels using directional antennas. However, one has to pay attention to the local rules for the ISM bands.
The next stage in extending the range is to use the Multi-Modem Architecture. It doesn’t extend the range of a particular device, for example, the radio range of the Super-Modem. However, the approach lifts virtually any limitation on the total size of the indoor positioning system.
How many tags can the system track?
Basic Starter Set Super-MP can support up to 250 beacons (mobile and stationary combined) out of the box.
If you need more – a few hundred to small thousand beacons, just let us know via info@marvelmind.com. We will implement a special software modification.
The Multi-Modem Architecture supports tens of thousands of beacons, which is enough for the most extensive networks.
Trilateration vs. triangulation
Marvelmind indoor positioning system is using trilateration – not triangulation – because trilateration-based systems show the most accurate result for real industrial applications: robots, forklifts, people tracking.
Triangulation-based systems can be also be good for some cases:
– Laser scanners with reflectors
– Optical systems for VR/AR
– Optical positioning for the last 1-100cm
Interferences
Interference can affect the accuracy and overall performance of an indoor positioning system.
Like in communication systems, level of the interference doesn’t matter directly. What matters is signal/(noise+interference) ratio.
Thus, for example, if you have a very-very noisy area and the system doesn’t work anymore on a 30m-submap, it can work on a 20m-submap or a 5m-submap. Signal/interference ratio will be times better.
The same is applied to other types of interference as well.
What interference can affect the IPS depends on the underlying indoor positioning technology:
– Ultrasound: strong acoustic noise coming to ultrasound band
– LIDARs and optical: too much or too little light
– UWB and other radio related: too strong radio
– BLE or WiFi: any moving objects that distort the EM field
Since Marvelmind Indoor “GPS uses not only ultrasound for ToF, but radio for clock synchronization, radio interference for a telemetry and other devices in the same ISM band con interfere or even block Marvelmind Indoor “GPS”.
– Subtle clicks produced by ultrasound transducers in quiet rooms
Is it possible to use IPS outdoors?
Yes, it is possible to use indoor positioning systems outdoors.
It doesn’t matter where the system is used indoors or outdoors as soon as the main requirement is met:
For tracking, the mobile beacon must have a direct line of sight (hearing) to two or more stationary beacons within 30 meters for 2D or three or more for 3D.
Read more: Outdoor local positioning system
How to get direction or orientation?
It is possible to easily get the direction or orientation of a mobile object by installing two or more mobile beacons on the object with a base of 30-100cm.
Can we get the Location and Direction in NIA, MF NIA, and IA?
– Yes, all three architectures work similarly
Example NIA:
– Tracking a small robot in NIA – the Paired Beacons
Examples in IA:
– Autonomous Robot Boxie driving
What are submaps?
The indoor positioning system consists of several key elements:
– The map
– Submaps