- Asteroid Weak Gravitational Attachment and Sampling
Asteroids are relatively intact remnants of the early formation and evolution of the solar system, which have a significant impact on the evolution of the earth’s environment and the survival of human beings. The asteroid exploration has the following important significance:
a) It can explore the formation of the solar system and the origin of life on Earth and other scientific issues;
b) It can study the orbital dynamics characteristics of the asteroid and establish the asteroid warning defense system;
c) It can exploit the rich mineral resources of the asteroid to alleviate the resource crisis of the earth;
d) Asteroids are numerous and widely distributed in space, which can be used as a “natural springboard” for exploration of deep space and provide a lot of basic materials for the establishment of space facilities and interstellar navigation transfer system.
Since the 1990s, the United States, Japan, the European Union and other countries have sent spacecraft to carry out various forms of asteroid exploration, such as fly-by, companion flight, anchoring and sampling return.
China’s asteroid exploration project is about to be approved, and expect to send the first asteroid probe to a near-Earth asteroid in 2022 for anchoring and sampling mission. The technical difficulty of the asteroid exploration project lies in the anchoring and sampling on the surface of the weak gravity asteroid. The surface of asteroids possesses two core characteristics: weak gravity and uncertainty. Asteroid exploration is different from moon exploration and Mars exploration. Due to the large variety of asteroids and their different characteristics, and the lack of prior knowledge, human’s understanding of asteroids is very weak. Up to now, there have been only 17 international missions to asteroids, most of which are fly-by missions, and there is no international precedent for successful anchoring on an asteroid. Among them, the United States and Japan are the most representative. The American probe, Osiris, is equipped with a four-degree-of-freedom robotic arm and adopts the sampling method of ”TAG” (Touch-And-Go). The sampling time is only a few seconds, and the probe wasn’t anchored on the asteroid surface. The Japanese probes Hayabusa and Hayabusa 2 also conducted sampling in the way of “TAG” with the slender cylindrical sampler in the center of the bottom plate, and the probes weren’t anchored on the asteroid surface as well. In addition, the ESA probe Rosetta aims to carry out anchoring and sampling with 67P comet nucleus, which has similar weak gravity and uncertain surface environment to the asteroid. The lander Philae carried with it adopted a harpoon anchor, but failed to be anchored successfully in practice, leading to subsequent sampling failure. China’s asteroid exploration missions have been limited to the “Chang’e-2” fly-by probe of asteroid 4179 Toutatis in 2012, which obtained clear remote sensing images of the asteroid. A worldwide wave of asteroid exploration is under way. Throughout the international asteroid exploration missions, anchoring and sampling exploration has gradually become the dominant exploration method, and it can also obtain more abundant exploration results. Against this background, China’s engineering goals are ambitious, while the technical difficulty of anchoring and sampling on the asteroid surface is also imaginable. Like the “Chang’e-4” probe that landed on the back of the moon for the first time, the successful surface anchoring of an asteroid will be the first of its kind in the world, representing the first time that humans have completed the surface anchoring and sampling under weak gravity. It will be a milestone in the field of deep space exploration in the world, which will greatly enhance the international influence of China’s space science and technology.
In 2017, State Administration of Science, Technology and Industry for National Defense organized China Academy of Space Technology (CAST) and Shanghai Academy of Spaceflight Technology to demonstrate the implementation plan for asteroid exploration, which mainly needs to tackle the problem of high reliable anchoring, and it greatly troubles space scientists and engineers. Under the leadership of Prof. Deng, we have put forward multiple ultrasonic drills cross drilling, geometrical forces closed anchoring scheme, as the core technology written into the asteroid exploration implementation plan. The team of Prof. Deng has maintained close cooperation with CAST, developed the a prototype based on robotic arm anchoring and sampling, a prototype based on landing leg anchoring and sampling, and fully carried out the test and validation in the zero-gravity environment. At present, the research focuses on the following aspects:
a) on repeatable electromagnetic buffering based landing technology
b) on highly reliable anchoring technology
c) on space environment adaptability of ultrasonic drilling
d) on the surface sampling technology on weak gravitational asteroids
- Design and Control of Mars UAV (Unmanned Aerial Vehicle)
Mars in the solar system is similar to the earth’s physical volume and topographical features, and it completely records the birth and evolution of planets in the solar system in the past five billion years. Therefore, Mars exploration is of great significance for expanding the living space of human beings and exploring the origin of life. The Soviet Union and the United States launched probes to Mars in the 20th century, but only limited exploration has been made to Mars. It was not until the 21st century that the United States launched several more rovers and obtained limited data on the surface environment of the landing zone. In view of the current rovers have not been equipped with large-scale visual detection, 3D map construction of unknown terrain of landing area and autonomous path planning, hard to avoid the risk of mechanical system failure caused by obstacles, sand subsidence and other conditions, considering comprehensively the atmospheric conditions of Mars and flight feasibility, a vehicle with a visual system is developed to construct a 3D terrain map of the target area of the rover, and plan the obstacle avoidance and trap avoidance paths of the rover, so as to meet the requirements of the autonomous navigation function of the rover in a large range. In addition, the local detection capability of the UAV can be used to observe areas difficult to reach by the rover at fixed points, so as to improve the efficiency of the Mars exploration mission. In the 1970s, Europe and America began to study the fundamental theories and design methods of the Mars UAV, but China’s research in this field is still in its infancy.
The prototype development of Mars UAV in Europe and America mainly includes four types: floating air balloon, fixed wing, rotary wing and flapping wing. The floating air balloons are susceptible to the Martian wind and difficult to achieve flight control. The take-off of fixed wing UAV needs a range of flat terrain so it’s difficult to complete repeated landing on the surface of Mars. Flapping wing UAV is still in the development stage and has not been extensively applied in the earth environment. As an aerial detection platform, rotary wing UAV has several advantages such as stable flight, vertical take-off and landing, has vital significance in Mars exploration missions, mainly reflected in:
a) When the rotary wing UAV is hovering or moving at a low speed, it can conduct high-resolution observation of the target area;
b) The rotary wing UAV can expand the rover’s field of vision and avoid the rover from entering the sandpit and other dangerous areas;
c) The rotary wing UAV can carry out extended research on the difficult reach area of the Mars rover;
d) Rotary wing UAV with take-off and landing capability can complete multi-point sampling and return to rovers for sample analysis.
Therefore, in order to accelerate the process of using Mars UAV for scientific exploration, it is necessary to develop a rotary wing Mars UAV.
Currently, NASA’s Jet Propulsion laboratory has developed a prototype of the Mars UAV and plans to launch it together with a rover in 2020 to expand the rover’s field of vision and assist the rover in completing path planning, thus improving the rover’s detection efficiency. At present, China’s Mars exploration mission has been formally set up. In view of the strategic needs of the mission, it is urgent to carry out forward-looking and innovative research on Mars UAV, so as to solve the fundamental scientific problems in the bottleneck of key technologies and change the backward situation of related research on Mars UAV in China. In view of the fact that China has not yet mastered the actual Mars atmosphere detection data, it is necessary to construct a low-altitude dust atmosphere model for the landing area to determine the working boundary conditions of the Mars UAV. The thin and cold atmosphere on Mars makes the rotary wing in the coupling state of low Reynolds number and high Mach number, so it is necessary to establish the aerodynamic theoretical system of the rotary wing according to the particularity of Martian atmospheric environment. In order to adapt to the Mars atmosphere environment with high coupling of multiple physical fields and wide range of environmental parameters, it is necessary to put forward a configuring method of the combined rotary wing system with compact structure, high flight efficiency and stable performance. Mars UAV is faced with disadvantages such as lack of GPS navigation and delays in signal transmission between Earth and Mars. It is necessary to put forward the adaptive control and relative terrain navigation method of the UAV to realize autonomous navigation, obtain the high-precision terrain information around the rover with the large field of vision of the UAV, and further improve the path planning ability of the Mars rover.
Mr. Jiadong Sun, “two bombs, one satellite” meritorious scientist and recipient of the Medal of the Republic, has assigned Prof. Deng a difficult task: to conduct research on the Mars UAV. Under the leadership of Prof. Deng, our research focuses on the following aspects:
a) on numerical simulation of Mars flight environment and analysis of flight conditions
b) on design theory and method of airfoil with low Reynolds number
c) on aerodynamic characteristics and configuring methods of rotary wing of Mars UAV
d) on autonomous flight control methods in the absence of information
e) on prototype development and performance evaluation of Mars UAV
- Existing Instruments and Equipment in the Laboratory
a) Triaxial vibration test bench: Sinusoidal excitation force range 1~70 kN; Sinusoidal, random, impact and other test functions
b) High and low temperature laboratory box: temperature range: -80~200℃; Temperature uniformity: ≤2℃; Temperature deviation: better than ±2℃
c) Vacuum tank: Temperature range: -100~200℃; Vacuum: better than 10E-5 Pa; Internal space: Φ 800 mm
d) High-speed camera: highest resolution 1280*1024@1800 frames/second; Maximum shooting rate: 67140 frames/second
e) Impedance analyzer: Frequency range: 5 Hz ~ 13 MHz; Frequency accuracy: ±50 PPM
f) Mars atmospheric environment simulator: 3 meters in diameter; Height: 3m; Pressure range: 10~10000 Pa; It has the function of simulating the composition of Mars atmosphere
g) Laser tracker: 6 degrees of freedom; Dynamic measurement speed: 1000 points/second; Can detect concealment point, obtain corner and inside characteristic
h) Asteroid terrain simulator: overall size: 3×3×0.5 m; Degree of relief: ±20 cm; Normal residual velocity: 0~ 0.2m /s; Tangential residual velocity: ± 0.1m /s
i) Speedgoat Semi-physical Simulation System: Power supply voltage: 9~ 36V DC; Slots: 3 PMC/XMC boards and 2 mPCIe boards; 16-bit analog I/O module with 32 differential synchronous analog inputs
j) Star rock ultrasonic drilling detector: the maximum power is 100 W; The working frequency of transducer is 20 kHz; The power regulation range is 20%~100%; Drilling pressure: 10 N; Drilling rate: 50~100 mm/min
- Software and Hardware Commonly Used in Laboratory
a) Switzerland MAXON, Faulhaber DC servo motor, Panasonic AC servo motor
b) ADVANTECH Industrial control computer, PC104 embedded computer, Raspberry, STM32 microcontroller
c) Japan KEYENCE high precision laser displacement sensor
d) German HBM force and torque sensor, American Honeywell torque sensor, and American Vibrac Electro-optical torque sensor
e) American Futek MTA600 triaxial force sensor, German ME triaxial force sensor K3D160
f) American MicroStrain gyro
g) FLINTEC strain gauge from Germany
h) Omron rotary encoder, Japan
a) Mechanical design tools: AutoCAD, SolidWorks, Inventor, UG
b) Electrical design tools: AutoCAD Electrical, Altium Designer, Promise-E, ELCAD
c) Simulation analysis tools: ANSYS, MATLAB, ADAMS, EDEM, Catia
d) Software development tools: Linux, Qt Creator, MDK
e) Tools for paper typesetting: Word, Latex and Photoshop
AMT laboratory has good experimental conditions and perfect experimental equipment. Aiming at cultivating high-level research talents, AMT laboratory conducts academic research and engineering implementation centering on the special needs of in-orbit and ground testing of aerospace mechanism in the aerospace field. The members of the laboratory can solve practical engineering problems by using the professional knowledge skillfully through many scientific research and practice opportunities, so as to improve the students’ application ability of machine, electricity and control. Students can further learn professional knowledge and conduct in-depth research in specific engineering directions and academic fields, so as to have the ability to independently develop electromechanical systems and engage in scientific research independently. The laboratory has a profound cultural background, which has gone through a long period of time. On the premise of constantly improving individual ability, it strives to cultivate students’ ability of organization and coordination, teamwork and strong sense of responsibility.
All PhD graduates have the opportunity to work in research institutes of aerospace institutions or domestic universities, and all master graduates have the opportunity to continue their studies in domestic or foreign universities, or to work in aerospace institutions and well-known domestic companies and enterprises. Graduates from the laboratory spread all over the country, have their own good development prospects, always adhering to the “Strict Standard and Sufficient Effort” spirit of Harbin Institute of Technology.
- Master Student: 12 person(s) / year, of which 9 in mechanical design and theory and 3 in aerospace manufacturing engineering
- Doctoral Student: 6 person(s) / year, of which 4 in mechanical design and theory and 2 in aerospace manufacturing engineering