Vol.47 ARDUPILOT that rapidly penetrates with Japanese industrial drones

From June 14 to 16, 2021, Japan Drone 2021 was held at Makuhari Messe.The content is this DRONE.Please check it out because it is also featured on the JP site.

For three days, I spoke with the booths and talked to the drone, including a seminar lecturer and JAPAN DRONE BEST AWARD judges for three days.There have been many people who have been in the directors for a long time, and I realized that they were going on a lot.

I felt that it was an exhibition with many highlights, such as the seriousness of each carrier's drone and the attractive AirPeak of Sony, but the biggest surprise for me was the spread of Ardupilot.

The background of Ardupilot expansion

Despite various concerns about Chinese drones (mainly DJI), DJI's general -purpose aircraft share was overwhelming due to the ease of handling of DJI machines.And domestic industrial drones also offered a Flight controller like NAZA-M and a frame that is easy to make, such as a flight controller like NAZA-M, and the S series (S600, etc.), so the aircraft that adopts the DJI flight controller.There were many manufacturers.

In 2019, as the flow of China's risks appeared, the shift from the DJI flight controller began, especially among aircraft manufacturers that are paid to public institutions and major companies.The trend has become stronger after the publication of "Response to Drone Security Risks" at the "Related Office Liaison Conference on Small Unmanned Aircraft" was announced last September.

This shows the policy for the entire security risk of drones, and is not necessarily referred to as "China Risk", but since this document, major user companies are promoting drone practical use.In addition, the development of aircraft equipped with a flight controller made in China (effectively DJI aircraft and DJI flight controllers) has not passed by the board of directors.

Makers equipped with DJI's flight controller (Naza-M V2, A3, etc.) may have several options in their shift, but from the perspective of their acquisition and technical information, open source pixhawk system.There were overwhelmingly many companies shifted to flight controllers.

And there are PX4 and Ardupilot's firmware on this pixhawk system, as described in the previous column, PX4 is dancing mainly in the United States.However, in Japan, the fact that there are few technicians, the information about PX4 is not systematized, and in the case of PX4, only the core part has been opened, but it has been more sophisticated.As for the function, it is difficult to implement it by each aircraft manufacturer (this is a license form), so I think many aircraft manufacturers choose Ardupilot.

However, many Japanese aircraft manufacturers have continued from the manufacturing of radio control aircraft, so there are many companies and engineers who have been good at the balance of frames, parts, other hardware, and arrangement there.There are few drone software engineers.

When equipped with a DJI flight controller, there are many cases where adjustments are made using DJI tools (such as DJI Assistant), and there are few manufacturers that are depressing inside, and DJI SDK (Software Development Kit: Development: Development: Development: Development: Development.There were few aircraft manufacturers developing using kits for people).

What the aircraft manufacturer should do to develop an aircraft

■ Hardware selection

When the aircraft manufacturer develops an aircraft, first decide the framework and size of the aircraft according to the application and necessary specifications.In the case of autonomous aircraft flying in the sky, the method -multicopter, single rotor, fixed wing, VTOL, etc. will be considered in the applications and necessary specifications.

Even if a multicopter is selected, it is natural that 4, 6 -piece machine, 8 -piece aircraft, etc. need to be determined early in the development plan (this is a loading weight "payload" or risk reduction.Choice. It is necessary to consider the flight time and cost as a barter).

Up to this point, many aircraft manufacturers understand, and many companies are good at it.At the time when the outer shape is determined, various parts will be selected.Flight controllers, batteries, power control, motor, propeller, ESC (motor control), transmitter, etc., especially motors, are selected according to the payload.

■ Calculation of still thrust

T = (D × 0.1) 3rd x (P × 0.1) × (N × 0.001) 2 -square x KT: Still thrust (gram) D: propeller diameter (inch) P: propeller pitch (inch) n: propeller rotation speed (RPM) k: propeller coefficient (21-22)

Example) LIPO battery: 3 cells (cell: 3).7V) KV motor rotation speed: 2300kVD propeller diameter: 11 inch P propeller pitch: 5 inch v = 3.7 × 3 = 11.1VN = KV x V × 0.5 (50%) = 2300 × 11.1 × 0.5 = 12765 (RPM) k = 21t = 1.1x1.1x1.1 × 0.5x2.765x2.In the case of 765 x 21 ≒ 2277 (gram) quad: 2277 x 4 ≒ 9kg

In addition, it affects the aircraft control depending on the angle of the propeller (basically, if the angle is deep, it is possible to move rapidly, but if the thrust is inferior and the angle is shallow, the thrust will increase but the movement is slow).。

In the future industrial drones, it is important to select parts such as batteries and motors as well as flight controllers from the viewpoint of increasing safety and stability.From the perspective of troubles, the number of recently increasing is also important to select two -way ESCs (usually ESC is a one -way signal, but in that case, it can be controlled and monitored to the motor of the power supply., In some cases, information such as the stop of the motor cannot be obtained, and it is not clear even if logging is taken).

■ Software installation and setting (for Ardupilot)

When the aircraft is assembled, install the Ardupilot firmware on the flight controller.It is common to select which version of the firmware to install (basically have the operation verification) and install it from GCS such as Mission Planner, but the firmware version control is an important factor in the future.As it comes to it, it will be necessary to use such a management mechanism (such as a cloud service).

Regarding the settings, there are calibration and parameters (tuning) settings.

Calibration

Calibrationは各センサーや部品の個体差や環境誤差を整えるための作業である。Calibrationに関しては、以下のものがある。

Compass, acceleration sensor, radio (RC / Propo), ESC

After this, the parameter will be set, but the parameter settings will be performed in the actual work using the actual machine, so at this stage, the flight mode switch setting will be performed once (basically in the CH5 of the Propoel (basically the CH5 of the Propoel.setting).

Representative flight mode

Parameters (tuning)

Understanding this parameter is important for the aircraft function, stability, and risk avoidance.By setting this parameter, the tuning of the aircraft is performed, but setting the parameters individually is very difficult, so basic tuning and autotune tuning are prepared.However, in the end, the stability is improved (such as parts, individual differences in parts, operability, etc.) while adjusting the parameters in detail.

Fail-safe

そのほかの設定としては、バッテリーの減少、通信（プロポ・テレメトリー）の切断、GPSロスト、ジオフェンス（飛行制限区域）などのFail-safeの設定がある。

As a aircraft manufacturer, we need software development

Basically, by performing the above work, the aircraft control and aircraft management with the basic function of Ardupilot are possible.

The aircraft manufacturer receives various questions regarding various software development, but especially when adding functions, it is often the case that Ardupilot has already been implemented as a basic function, and it accompanies it (for example, a rider for altitude detection).It can be implemented in the aircraft and can be added simply by setting it up, and in fact software development is not necessary.The following cases require software development.

New flight mode

The development of a new flight mode is when you want to develop other than the flight mode described above.

For example, a mode that descends while performing a circle operation such as a dive mode (if you descend directly when descending, the aircraft will be unstable and tend to be turned upside down, so if you want to drop a stable while stably, you are good at piloting.People use the technique of descending while performing a circle, but they do that automatically).

There are two ways to develop a new flight mode, one way to pull the source in a similar mode and remodel the mode (how to copy the circle mode in the rapid mode and remodel it).And use a programming language called Lua script to combine existing flight mode.

The former can be developed relatively freely, but the development of flight mode has a lot of influence and some may have a serious effect, but the latter is a sandbox method, so the core is core.Because it does not work in the flight code, it can be developed relatively safely.In order to implement the code in Ardupilot, the former needs to step on the process such as pull request through gitHub, but the latter does not require such a process.

Development of device driver

Development of drivers to recognize and operate devices related to aircraft control with a flight controller.

New functions and stabilization for other aircraft control

This development requires deep knowledge (self -position estimation, collision avoidance, non -GPS space, etc.) because it is a more linked development regarding aircraft control.

Up to this point, the content is modified or newly coded in the flight code described in C ++.Other aircraft control or aircraft management system is developed using a companion computer such as Raspberry Pi.

Development of advanced aircraft control

A typical example is the aircraft control in non -GPS spaces such as SLAM (Simultaneous Localization and Mapping at the same time), and various other developments have been developed, such as taking action by markers.Basically, it is connected using a message protocol in a communication layer such as a flight controller and a Mavlink, and controls the aircraft using a flight mode such as GUIDED.

Aircraft log analysis

In the development of the aircraft, it is essential to adjust while logging the aircraft to renovate and stabilize the trouble.Ardupilot has two logs.One is a telemetry log, and the other is the data flash log.

A log recorded in the Ground Control Station (GCS: Mission Planner) connected to receive information on aircraft information called Telemetry Log Telemetry.It is mainly a log of the information indicated on the aircraft and the GCS.

Internal log of the aircraft recorded in the data flash log flight controller.

Data to check well

Log analysis example

An abnormality is seen in the part where the above graph suddenly deviates.

As shown so far, in the development of aircraft, it is necessary to implement and develop various functions as well as simply adjusting to stabilize flights and behaviors and add new functions.In addition, in order to stabilize there, it is necessary to improve and modify by analyzing detailed tuning and log data.

For aircraft manufacturers, it is important to understand these things and secure human resources that can implement and develop.

Arduex Japan Co., Ltd. was founded in May.Aldux Japan is a company to develop and support aircraft manufacturers equipped with Ardupilot.

It is not a development contract but a development support is that once the drone is developed, it is not the end, but it is necessary to continue development and renovation, and software human resources in each aircraft manufacturer.This is because if you do not train, you will not stand, and we will continue to go together.

The big advantage for Japan is Randy Mackey, a top engineer of Ardupilot and also responsible for the CTO of Arduex Japan, living in Japan and understanding Japanese.I think it is very important to take advantage of the interests.