Today, the second experimental cabin of of my country's space station, China Aerospace Science and Technology Corporation, developed by the Eighth Academy of China Aerospace Science and Technology Corporation, was successfully launched into orbit at the Wenchang Space Launch Site. Subsequently, the Mengtian experimental cabin will complete lateral docking with the core cabin and permanent parking through the large inertia plane indexing. The space station will form a basic configuration of the "T" character. The Wentian and Mengtian experimental cabins will each drive the four large flexible solar wings on the outermost side of the two experimental cabins to rotate simultaneously, officially starting their respective directional journeys toward Japan and realizing the "two wings and double flights" of the space station.
Question 1: What is "double degree of freedom to the daily orientation"?
my country's space station flies around the earth for about 16 circles a day. In order to enable sun wings to achieve stable alignment of the sun like sunflowers , ensuring that every ray of sunlight shines vertically on the sun wings, the solar wings of the two experimental cabins of Wentian and Mengtian in my country's space stations have two degrees of freedom to the sun versus β. By moving two vertical directions, the maximum power generation efficiency of the sun wings is achieved.
. Visually speaking, the space station in space is like a ship swimming on the sea. The sun wings are like a huge "sail". The angle of this "sail" needs to be adjusted in real time to achieve the maximum range of sunlight on the sun wings and ensure power generation efficiency. To this end, the designers installed two drive mechanisms at the end point where the sun wing and the cabin are connected. The function of the driving mechanism is to drive the sun wings to rotate with the sun's light angle through its own movement. The two driving mechanisms installed on the experimental compartment will drive the solar wings to flip and rotate through different working modes. For example, one of the mechanisms can rotate the sun wings 360° axial direction around the experimental chamber according to the orbital motion of the space station and its angle with the sun, ensuring that the wing surface is always facing the sun; the other mechanism can adjust the sun wing surface horizontally according to the sun's incident angle to ensure that the wing surface is maximized to receive sunlight and improve power generation capacity. Taking our hand movement as an example, one mechanism realizes the back of the palm of the hand and the back of the hand, and the other mechanism realizes the 360° rotation of the wrist. This is the simple principle of the sun wing double degrees of freedom to the sun.
Question 2: What is a "daily-oriented device"?
Both the Wentian and Mengtian experimental cabins are equipped with a sun-oriented device, which is a mechanism responsible for 360° rotation of the solar wings. Simply put, the sun-oriented device mainly has two functions. One is responsible for driving the overall rotation of the sun wings of the Wentian and Mengtian experimental cabins, and the other is responsible for transmitting the energy generated by the sun wings into the cabin.
is the "guardian" and even more the "warrior". In order to ensure the power consumption needs of the space station, the total area of the flexible solar wings arranged on the experimental cabin is 276 square meters on both sides and the total mass reaches 1.2 tons. Because of the pair of "big wings" on the head, the large-scale sun-to-dragon directional device must be strong and rotating. If we imagine that we hold two 27 meters long and have a huge moment of inertia in one hand, and rotate 360° with the wrist as the center, our wrist requires strong load-bearing ability and rotational power. The sun-to-normal device in the experimental cabin is equivalent to our wrist, which needs to drive the sun wing to continuously rotate and stabilize the sun-to-normal.
does "physical work" and even more "fine work". A precise angle information detection sensor is installed inside the sun-oriented device. While the sun wings rotate, the rotation angle information is collected in real time and uploaded to the attitude control system. At the same time, the attitude control system issues motion control instructions according to the rotation angle of the space station running track, and then conducts autonomous motion planning for the sun directional device, and accurately adjusts its own status at all times. In addition to being accurate, the more difficult thing about
is how to control such a large and soft sun wing smoothly. The total area of the solar wings of a single experimental compartment is 276 square meters after the two sides are unfolded, but it is only as soft as the printing paper, and any slight vibration can make it sway and swing. If the sun wings rotate unsteadily, it will cause difficulties in controlling the attitude of the space station.Therefore, the "large flexible high-stability servo control system" came into being. This control solution tailor-made for the sun-oriented device allows the sun wing to "dance with long sleeves" and achieve stable tracking and control of the sun. What's more powerful is that when the sun wing is disturbed by external interference, the control system of the sun directional device can be very sensitively detected and "quickly soothed", just like " Tai Chi Push Hand ", it becomes invisible, and can be dissipated in time in less than 30 seconds, giving the space station "stable happiness".
is ready to go, and we must first open up the "energy context". For the space station, the sun is a natural "large power plant". But how to transmit tens of thousands of watts of electricity generated by large flexible wings to the space station, build a stable and efficient "energy lifeline", and make the space station truly "worry-free electricity use"?
Generally speaking, most spacecraft adopt the traditional slip ring conductive transmission method. Simply put, the slip ring is a "rotating joint" used to connect and transmit energy. However, due to the sliding wear, this method is generally only suitable for spacecraft with kilowatt-level transmission power. The power transmission demand of space stations is more than 20 times that of ordinary spacecraft, and the design life requirements are high. If the sliding ring conductive transmission method is selected, the loss caused by sliding friction can be said to be a considerable waste of energy for the space station. To this end, the development team of the 805 Institute of the Eighth Hospital has created a rolling ring electric transmission mechanism with ultra-high power and ultra-long life, realizing the first high-power transmission in China that replaces sliding contact with rolling. The rolling ring looks like a round tire, with a round shape overall. It adopts a movement principle similar to rolling bearing , including "inner ring body" and "outer ring body", and multiple "flexible rings" are embedded between the inner and outer ring bodies. During operation, the outer ring is fixed and the inner ring rotates. The inner and outer ring bodies are electrically connected to with the equipment outside the cabin and in the cabin through cables. In order to verify the high reliability, high efficiency and long life of the rolling ring, the development team conducted an accelerated life test test on the ground for 200,000 loops, which is equivalent to 34 years of working in orbit, ensuring the efficient and smooth flow of the space station's energy path with high reliability.
In the vast space, the orange sun wings stretched its wings. Under the wings, the large sun-facing directional device and driving mechanism rotate gently and steadily, moving forward day by day with " Tiangong ". At this moment, the performance of the Japanese directional device and driving mechanism has just begun. They will do their best to ensure that the Chinese people's own space stations fly together and move forward steadily.
Author: Shi Bozhen Li Tong Qian Zhiyuan
Picture: China Aerospace Science and Technology Corporation Eighth Academy
Editor: Tang Weijie
