28 December 2016
The self-flying passenger-carrying EHang 184 drone has started flight tests. The Chinese company EHang has issued the following report, video and photos:
Since its debut at CES in early 2016, the EHang 184 Autonomous Aerial Vehicle (AAV) had been attracting worldwide attention of global media as well as the general public. Thus, our engineers deeply feel that we carry higher expectation than ever that comes along with excitement.
Our whole concept of the EHang 184 includes not only a safe, smart, eco-friendly AAV, but also a comprehensive system and service solutions behind to ensure the flight safety. From the perspective of the AAV itself, we delve into key factors of safety, performance, flight duration, distance, etc.
Our engineer team has done a series of flight tests – gradually, from the base flight tests for attitude adjustment, and then we passed to a hovering test. In the near future, we can expect autonomous flight test under 4G network with load.
As the EHang 184 might be the multi-rotor aircraft with the world’s largest propeller, in order to avoid the problem of “control divergence” in its autonomous flight, we need to do a variety of algorithm optimizations for the flight control system to ensure that such a large multi-rotor aircraft can fly in the air stably.
The auxiliary system and projects share the same significance with the EHang 184 aircraft. Security is always the highest level of requirements for the EHang 184 as an unmanned aircraft.
The aircraft is not only able to automatically resist normal wind and obstacle, and adapt to different kinds of normal weathers, but also able to let passengers know that even if any component anomalies within the aircraft or any unexpected flight conditions happen, our ground personnel will be informed and take appropriate measures at the first time, allowing passengers as well as the aircraft to land safely as soon as possible.
Therefore, we started to construct and finally set up a special flight command center designed for EHang 184 in 2016, a ground command center that will accurately monitor a variety of flight data of EHang 184 and dispatch air traffic.
In short, the command center will not only enable the passengers in the air to make real-time video/voice calls with the ground, but also receive the real-time flight sensor data from every EHang 184 in the air, so that passengers will understand the real-time flight conditions through one-on-one calls with our ground staff at all times without much tension for the flight journey.
We acknowledge the fact that EHang 184 is a project which investment and operation costs will be far greater than its proceeds today and in the future for a period of time before it achieves a certain scale of commercialization. Even so, we believed in what we do, and took a year to set up the command center and run into trial operation, because it is an indispensable and important part of the EHang 184 system in the future.
As for a multi-rotor aircraft, the propeller is the most important power driver, which affects the aircraft dynamic performance, flight stability, noise and many other core indicators.
We have designed and upgraded three versions of the EHang 184 propeller. The first-generation propeller mainly meets the requirement of flight test in early flight. In the second generation, its performance is further improved that the limit drag of the single propeller reached 87kg, meeting the need of EHang 184 flight in a variety of environments. The third-generation propeller design not only improved the aerodynamic efficiency for 10%-15%, but also reduced the noise generated by rotation.
The motors of EHang 184 have been upgraded to the third generation. The first-generation was 13830, which had lower magnetic cylinder, and inferior performance in drag and other aspects. The second-generation motor was 12845, which had higher magnetic cylinder and more stable performance, and provided a drag that is up to the design requirement of EHang 184. The latest generation motor is 18030, which has promoted power and the maximum drag.
The flight controller system plays a vital role like “the brain” for an aircraft. Since there were no appropriate solutions in the market that could be directly adapted to EHang 184 at present, we independently developed a sophisticated flight controller system specially for EHang 184 through innovating a large variety of algorithms, which could ensure the effective control and flight stability of such a multi-rotor aircraft with huge inertia and load.
At present, the flight control system of EHang 184 has full redundancy design with two sets of system, each equipped with two sets of sensors, which can mutual communicate with each other. In the next version of the flight control system, we will upgrade better sensors with stronger performance on the reliability, anti-jamming capability and accuracy, to get more stable automatic control through more accurate aircraft attitude.
The battery of EHang 184 has been upgraded to the third generation. The current Battery Management System (BMS) is an industrial-grade solution that monitors the parameters of all cells, including the temperature of the cell, the current capacity and voltage, etc., for active and passive balance, which can effectively manage the battery performance and life. The Battery Management Unit (BMU) for the management of BMS, responsible for the real-time communication of BMS data with the flight control system and the ground station.
It has always been the dream and mission of EHang since its establishment to create a truly safe, smart and eco-friendly autonomous aerial vehicle. Although we recognize that there will numerous challenges to realize this dream, we will persevere to explore.
