LiDAR – Fixed Wing Vs. Multi-Rotor: Unpacking the Benefits

Definition: LiDAR, which stands for Light Detection & Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses—combined with other data recorded by the airborne system — generate precise, three-dimensional information about the shape of the Earth & its surface characteristics.

LiDAR has been historically a technology that could only be deployed by manned aircraft (helicopters, planes), cars, on backpacks, ships & submarines etc.

It’s been difficult to deploy, highly specialized & ruinously expensive. Yet, advancements in tech, design, processing & a cost-effective platform to deploy the sensors in the form of commercial drones has resulted in a wave of new lightweight sensors coming to market from brands such as DJI, Yellow scan, Quantum Systems & others.

The emergence of these lightweight sensors is fast-tracking the adoption of LiDAR technology across multiple industries globally, as well as the development of drones with the endurance capacity to deploy across diverse environments.

Despite the popularity & number applications being developed for use in agriculture, mining, infrastructure development, power line inspections, & more, choosing the right LiDAR system, platform, & operator is crucial to getting actionable & usable data. Not just a pretty 3-D picture.

As with any next gen tech, there are a number of key points you should consider when considering a LiDAR system or operator. To provide greater insights, we’ve spent time with our teams & Original Equipment Manufacturers (OEMs) to explore why the correct LiDAR sensor; drone & flights operators are critical to a successful outcome.

As with any next gen tech, there are a number of key points you should consider when considering a LiDAR system or operator. To provide greater insights, we’ve spent time with our teams & Original Equipment Manufacturers (OEMs) to explore why the correct LiDAR sensor; drone & flights operators are critical to a successful outcome.

Our Preference Currently Is Quantum Systems’ Trinity F90+ Vertical Take Off & Landing (Evtol) Drone Equipped With The Qube240 Lidar Sensor. Here’s Why:

Cost of Sensor & Equipment: Payload & Accuracy

The Qube240 LiDAR sensor by Quantum systems, has been transformative for the industry, as it is able to produce survey grade results of up to 3cm accuracy, & can be mounted on the Trinity F90+ eVtol aircraft. The reason is that it only weighs 700 grams, in comparison to its competitors that weigh 2kg.

While the lightweight characteristics of the sensor coupled with its accuracy should make it more expensive, it’s half the price of equivalent sensors. According to industry leaders, the competitive price point is due to the company’s proprietary tech & value chain efficiencies.

Why weight matters for drones

The downfall of these 2-kilogram sensors is that you can only use heavy multi-copter drones to carry them, resulting in limited flight time due to poor endurance. This directly translates into how large an area you can survey; how fast you are able to complete the mission & at what cost.

For example, a popular & costly solution currently being piloted involves, a DJI M300 multi-copter drone carrying a 2-kilogram LiDAR sensor that only survey a small area of 25 hectares in a maximum flight time of 20 minutes.

In comparison, the Trinity F90+ drone & Qube 240 sensor is able to survey 350 hectares in one-hour & at a speed of 60km/h. These speed & endurance benefits result in simplifying operations, as you can operate from a fixed location for longer, whereas with a multi-copter drone, your pilot is continuously moving from site to site due to the lack of endurance. This creates more operational & safety risks on site & during exploration, & quickly drives up costs.

What about the DJI L1 – it’s the same Lidar as the Qube?

A major driver of drone LiDAR services has been by global consumer drone leader, DJI, which has increased awareness of the technology through the extensive marketing of its L1 Sensor.

The challenge on this sensor; however, is not the accuracy of the measurement, but rather within the internal measurement unit (IMU).

When flying a drone equipped with a LiDAR sensor that is firing 240 000 pulses per second, it is critical that the pilot is aware of the position & attitude (roll, pitch, heading) of the sensor & drone.

If the aircraft pitches & rotates even by 0.011 degree, the LiDAR sensor will be looking at a different location on the ground. Critically, this is a key differentiation in the product tech stack & software of the Trinity F90 that accounts for all angles, pitch, yaw & heading angles to create survey grade accuracy. In comparison, the L1 sensor provides a 3-D data model that at first glance appears correct to the end user. However, when the data is examined, the noise & uncertainty multiply closer to 1m, or 80cm. This is due the Qube240 using a more advanced HighEnd Applanix APX15 IMU & the DJI uses a cheaper & imprecise IMU.

If you consider an 80cm incorrect calculation on a power line inspection, digital terrain model of a road, or trying to calculate the volume of a coal stack, this 1m discrepancy & uncertainty makes the data worthless to the end user.

Multi-copter Drift

A fixed-wing drone travels in a straight direction or vector. In contrast with a multi-copter drone, the aircraft goes up & down, sideways & more as it corrects its heading & plan, resulting in a so called IMU drift.

This IMU drift also negatively impacts the quality of the data, as it results in the LiDAR pulses hitting incorrect positions on the ground. Moreover, the position of the sensor on a gimble mount attached on multi-copter drone compared to the fixed downward position of a fixed-wing also creates further complications.

Speed of Data Acquisition

Another critical aspect of the Trinity F90+ is its software & tech stack that enables the high-speed data transfer compared to other platforms or technologies such as photogrammetry. Rocketmine, clients can expect a working 3D model of the flight in record time.

The current record is 45-minutes & is dependent on multiple factors, but regardless the data turnaround is fast!

Manned Aviation Vs. Drone

Drones are creating new use cases for LiDAR & deployment solutions for businesses.

A manned LiDAR solution’s primary benefit currently is covering large areas, such as state parks, town & provinces etc. However, progression in aircraft systems such as the Trinity F90+ eVtol system are increasingly more popular due to their costing & ability to fly at a 120m ceiling & well below the cloud cover. (Typically clouds sit at 200m too low for aircraft to fly safely). A major challenge for manned solutions is cloud cover as the LiDAR pulse cannot accurately penetrate it.

The Last Word

LiDAR is a new & increasingly capable tool in the arsenal of planners, investors, owners, operational experts & innovators across a multitude of sectors.

From mining houses looking to calculate stock volumes & other measurements to penetrating the jungle cover farmers looking to improve performance & infrastructure planners looking to build accurate modes, the applications are multiplying.

Yet, the challenge is understanding the benefits, the mission & whether you have the right technology partner & operator conducting your mission to ensure that the data you receive is actually accurate & usable.