Design Principles and Implementation of Advanced

Available online at www.sciencedirect.com

ScienceDirect Procedia Engineering 150 (2016) 1410 – 1414

International Conference on Industrial Engineering, ICIE 2016

Design Principles and Implementation of Advanced Simulators for Training Astronauts to Work In Zero or Low Gravity Conditions G.Ya. Pyatibratov, O.A. Kravchenko, A.M. Kivo* Platov South-Russian State Polytechnic University (NPI), 132, St. Prosvescheniya, Rostov region, Novocherkassk, 346428, Russia

Abstract Methods of creation and operating peculiarities of simulators for training astronauts to work in zero or low gravity conditions are analyzed. Principles of simulators’ construction using the forth-compensating system are considered. The results of theoretical and experimental studies of electromechanical forth-compensating systems are shown. Based on the analysis results of requirements and operating experience of existing simulators, the ways of their improvement are identified. The design principles and implementation methods of advanced simulators for training astronauts in the implementation of the lunar and Martian space exploration programs are suggested. © 2016 2016Published The Authors. Published by Elsevier Ltd. © by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016. Peer-review under responsibility of the organizing committee of ICIE 2016 Keywords: zero gravity; astronaut; simulator; forth-compensating system; elasticity; mechanism

1. Introduction Currently, on Earth, astronauts’ trainings to work in zero gravity conditions on space stations and in open space are carried out using technical means implemented using different physical principles. Planes-laboratories such as IL-76 MDK are used to produce a short-term (15÷25 seconds) zero gravity while the plane flies on a declining parabolic trajectory. Using the principle of neutral buoyancy pools with clean water are used to train astronauts wearing special spacesuits to perform an extravehicular activity (EVA). Simulators implemented by using electromechanical forth-compensating systems (EFCS) are used for extravehicular activity testing. Zero gravity imitation quality on simulators with EFCS is determined by the accuracy of compensation of an

* Corresponding author. Tel.: +7-909-401-6644. E-mail address: [email protected]

1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016

doi:10.1016/j.proeng.2016.07.337

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object’s weight, friction and inertia forces from additional mass attached to the object. Under this condition, the astronaut, wearing a spacesuit can move in the working space of the simulator under the applied force, with the movement parameters close to zero gravity. The development of modern astronautics predetermines flights to other planets and asteroids of the solar system in the nearest future. Among the first planets of practical interest for future development are the Lunar and Mars that involves an extensive human activity on its surface [1]. The implementation of Lunar and Martian programs will require improvement of the quality of astronauts’ training of rational working techniques and ways of moving in low gravity conditions. The analysis has shown that the simulators design using the principle of force-compensation is one of the most promising areas of their construction and improvement [2]. The main advantages of simulators with EFCS are the low construction and operation costs, the possibility of prolonged training in the air medium using standard equipment [3]. The development of the theory of EFCS construction, the development of technical solutions for the advanced simulators design that allows simulating the movement of astronauts in zero and low gravity is an actual scientific and technical problem. 2. Problem statement In the initial stages of the advanced EFCS design, it is necessary to define the design concepts, ways of construction of advanced simulators to train astronauts to work in low gravity conditions of other planets. This requires formulation of requirements for advanced simulators for astronauts’ training, to perform an analysis of existing technical solutions, to justify the rational design of devices providing the required parameters of astronauts’ motion in the working space of the simulator, to justify the design concepts, research methods and rational ways of implementation. Solution of these problems will allow constructing and developing of simulators for astronauts’ training to work in conditions of zero gravity on space stations and low gravity of other planets. 3. Description of the subject Currently, the most perfect simulator to train astronauts to work in zero gravity conditions is the simulator “Vykhod-2” that has been used since 2002 in the State Organization "Gagarin R&T CTC" (Star City). With the help of this simulator, implemented using the force-compensation principle, astronauts acquire skills of spacewalking. Since 2011, after the EFCS upgrading, the simulator“Vykhod-2” has been successfully used for training cosmonauts and astronauts doing these and some EVA tasks on the ISS program. The “Vykhod-2” simulator, which is shown in Fig. 1, is a complex multifunctional system providing vital functions of astronauts in spacesuits with the possibility of their free movement in the workspace due to minor muscular efforts. [4] The simulator consists of two independently working overhead crane spacesuits’ weight relief devices that allow astronauts moving in the horizontal and vertical planes. For the ability of each astronaut to move in the horizontal plane, the bridge rotates around a central axis, and the trolley, on which there are rope transmission blocks of vertical displacement system (VDS) of the astronaut, moves along it. To reduce friction forces the bridge and the trolley are moved using air bearing lift system [3]. Vertical movements of the astronaut in a spacesuit are performed by using EFCS implemented using a rope transmission, a variable frequency electric drive (ED) and high-precision force control system in the spacesuit suspension device.

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Fig. 1. “Vykhod-2” simulator.

The “Vykhod-2” simulator’s workspace is characterized by a maximum spacesuit suspension height of 4.5 m, bridges rotation radius of 6.5 m and 7 m. The imitation of movement in zero gravitation of an astronaut in a spacesuit with a total mass of 200 kg on the simulator is provided with the force control error of not more than 30÷40 N. This allows the astronaut with the help of manual efforts to move with a maximum speed of 0.4 m/s and accelerations of up to 0.2 m/s2. 4. Defining the parameters of the astronauts movements and the size validity of the workspace of the advanced simulator To determine the implementation peculiarities of the advanced simulators’ EFCS it is necessary to analyze the working conditions and to determine the parameters of movement of the astronauts in the conditions of Mars and the Lunar. The force of gravity on Mars and the Lunar are respectively equal to 0.38 and 0.16 of the force of gravity on the Earth. Low gravity has a significant influence on the choice of rational method of movement of astronauts on the surface of other planets. The analysis of possible ways to walk on the Lunar and performed calculations have shown that the most energyintensive way for the imitation on the simulator of the astronauts movement will be jumping [5]. To determine the possible top speed and acceleration of the astronauts the maximum force developed by the astronauts in a spacesuit when making the jump, should be taken into account. The experiments conducted on the “Vykhod-2” simulator have shown that maximum force FE developed by the astronauts’ feet when jumping up are from 1600 up to 1800 N. Calculations carried out taking into account the acceleration of gravity on the Lunar gL = 1,62 m/s2 at the value of force FE = 1800 N and the total mass of the astronaut in a spacesuit 200 kg allowed determining the maximum values of the linear velocity V0 and acceleration a0. During the astronaut’s movement on a vertical plane V0LV = 1, 8 m/s , a0LV = 5,8 m/s2, and when he moves on the horizontal plane V0LH = 2,1 m/s , a0lH = 7,4 m/s2.. The received results are consistent with the parameters of movement on the Lunar of the American astronauts [6]. For Mars gravity conditions at the acceleration of gravity gM = 3,86 m/s2 the movement parameters of the astronauts by means of jumping will be on the vertical plane V0MV = 1, 45 m/s, a0MV = 3,5 m/s2, and on the horizontal plane, they will be the same as on the Lunar [5]. The comparison of the movement parameters of the astronauts in terms of gravity on the Lunar and Mars has shown that more dynamic are the movements of the astronauts on the Lunar surface. Therefore, when designing a universal simulator, the required electric drives energy opportunities and the size of the working space of the simulator should be determined by the parameters of movement of astronauts on the Lunar.

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Taking into account the maximum jump height of the astronaut on the Lunar, his height, the size of the spacesuit suspension device, astronaut zones of deceleration when reaching the boundary of the working space of the simulator, it is necessary to have a maximum height of the astronaut suspension point of at least 7.5 m. In this case, the suspension device of the astronaut in a spacesuit should provide the spacesuit rotation with the vertical axis of 180° and its tilts from the vertical position forward up to 70° and backward up to 20°. The possible length of the bridge of the horizontal displacement system (HDS) limits the width of the simulator’s working space. Preliminary calculations have shown that the potential static and dynamic loads, while minimizing weight and sufficient rigidity of the bridge structure, its length should be no more than 8.5÷9 m. The length of the working space of the simulator should be determined taking into account the possibility of an astronaut to fulfill a series of jumps. Considering the maximum length of a jump on the Lunar about 2.4 m, if it is necessary, to make two or three jumps for acceleration and two for deceleration, it is desirable to have the total length of the working space of a simulator of about 16÷18 m. The force of gravity on Mars is smaller than on Earth, but more than on the Lunar, so the amplitude and the width of the steps, as well as the range of jumps will be slightly smaller than the Lunar. The way to move on Mars may be something between the earth's walk and jumping on the Lunar. 5. The EFCS design problems of the advanced simulator A significant increase in velocity and acceleration of the astronauts when performing movements in low gravity compared to their movement in zero gravity will require a significant increase in power of the ED. Studies have shown that taking into account the real gravity, the necessary degree of astronauts’ weight relief, the possible velocities and accelerations of their movements, the maximum ED power will require for simulating the movements of astronauts on the Lunar [5]. To design advanced simulators with EFCS the following problems should be solved: x to implement a multi-channel structures of the EFCS mechanisms, possessing a minimum weight, small and stable friction coefficients, ensuring effective coordination of movement parameters of astronauts and drive devices; x to carry out a multivariate calculation of the required power range of electric drives and the choice of its supplying converters; x to determine the structure and parameters of the control devices to ensure the required accuracy of force control systems; x to implement optimal control laws of coordinates in multiply, nonlinear, with variable parameters and vibrational properties electromechanical systems, operating under the random effects; x to insure an information support of the VDS and HDS control processes, the control of the training process, the current status and the fault diagnosis of the equipment; x to supply the moving device of the simulator with electrical energy with minimal forces of mechanical resistances. The designing problems of a new generation of simulators are interconnected. Their complex decision allows creating high-performance simulators with advanced intelligence and functionality that will provide an effective solution to problems of cosmonaut training in various activities on planets with low gravity. 6. The proposed methods and techniques for the implementation of advanced simulators To create a new generation of simulators designed to train astronauts to work in conditions of low gravity it is necessary to: x implement the HDS using trolleys on wheels with AC electric drives, controlled in a deviation function of the rope from the vertical plane [7]; x create the VDS using the force-compensation principle, controlling the EFCS in a function of force change in the suspension of the object [3];

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x keep the astronauts in suspension at zero velocity and possibility of implementing the dynamic deceleration mode at the voltage failure of the power supply to use a high-torque electric drives with permanent magnet excitation [7]; x determine the rational parameters of mechanical transmissions and the required power of the VDS and HDS electric drives using multi-criteria methods [8]; x apply methods of active damping of ED of elastic vibrations of VDS rope transmissions [9]; x select the structure and parameters of the multi-axis EFCS in accordance with the approaches and recommendations, justified in the paper [10]; x perform the EFCS synthesis using methods of optimal force control in VDS rope transmission developed in [11]; x implement systems of providing a high-quality operation of the simulator in accordance with the guidelines given in [12]. Complex application of the proposed methods and techniques allows designing simulators with high performance and functionality. Currently, the Platov SRSPU (NPI) employees (Novocherkassk) are working on a technical project to create a long-term multi-simulator to train astronauts to perform tasks of expanded EVA on the ISS and activity in conditions of low gravity on the Lunar and Mars. Acknowledgements The paper results are obtained with the support of the project ʋ 2878 “Theory development and implementation of electro-technical systems of simulators complexes and mobile objects” executed in terms of basic part of the state assignment ʋ2014/143. References [1] G.Ya. Pyatibratov, O.A. Kravchenko, A.M. Kivo, D.D. Zubov, Prospects of creating simulators to train astronauts for action on planets with low gravity, in: Manned space flights: Procs. of the 10th Intern. scientific. Conf., Star City. (2013) 254௅256. [2] O.A. Kravchenko, G.Ya. Pyatibratov, N.A. Sukhenko, A.B. Bekin, Design concepts and implementation of compensation gravity systems, Izv. Vuzov, Sev.-Kavk. Region, Tekhnicheskie nauki. 2 (2013) 32௅35. [3] G.Ya. Pyatibratov, O.A. Kravchenko, V.P. Papirnyak, Methods and ways of improving the implementation of simulators to train astronauts to work in zero gravity, Izv. Vuzov, Elektromekhanika. 5 (2010) 70௅76. [4] O.A. Kravchenko, G.Y. Pyatibratov, Creating and operating experience of force-compensating systems providing multi-functional training astronauts to work in zero gravity, Izv. Vuzov, Elektromekhanika. 2 (2008) 42௅47. [5] A.M. Kivo, O.A. Kravchenko, Determination of the energy characteristics of the special stands providing practice for astronauts’ movements on planets with low gravity, Izv. Vuzov, Elektromekhanika. 3 (2012). [6] N. Armstrong, The study of the lunar surface, Earth and the Universe. 5 (1970) 23௅24. [7] D.V. Barylnik, G.Ya. Pyatibratov, O.A. Kravchenko, Forth-compensating systems with AC electric drives of training complexes for cosmonaut training, Lik, Novocherkassk, 2012. [8] G.Ya. Pyatibratov, Multi-criteria selection of electromechanical compensating systems of gravity forces during the vertical movements of objects, Izv. Vuzov, Elektromekhanika. 5 (1993) 65௅70. [9] G.Ya. Pyatibratov, The possibility of using electric drives for active clamping of vibrations of elastic mechanical transmissions, Izv. Vuzov, Elektromekhanika. 10 (1990) 89௅93. [10] O.A. Kravchenko, Principles of construction of multi-axis force-compensating systems, Izv. Vuzov, Elektromekhanika. 3 (2008) 43௅47. [11] O.A. Kravchenko, G.Ya. Pyatibratov, Synthesis of optimal force control in electromechanical systems with elastic connections, Izv. Vuzov, Elektromekhanika. 4 (1998) 58௅63. [12] D.B. Barylnik, O.A. Kravchenko, A.B. Bekin, Implementation features of restraint rotation speed and position modes in force control systems, Electrotechnika. 3 (2014) 39௅44.