Technology Demonstrator Vehicle Research Articles

Analysis on the Grounding Architecture of a Technology Demonstrator Vehicle

ABSTRACT In launch vehicles, Inter system and intra system interfaces exist among various onboard avionic modules. In addition to that, the on-board systems are interfaced to ground checkout system also which is yet another complex system. Isolation of grounds is an important concept in launch vehicle avionics system integration and design. Understanding ground loops and chassis potential is essential for achieving accuracy in measurements and prevention of failure propagation. This paper is a study of the grounding architecture of a Technology Demonstrator Vehicle (TDV). For this purpose, simulation models of on-board and checkout systems have been generated in ORCAD PSPICE. An attempt is made to understand the causes of chassis potential and ground loops. Monitoring networks are analyzed to determine its robustness against ground potential lift. The paper also discusses the grounding-related issues faced during the testing TDV and the methods adopted to overcome them.

Mission Design and Performance of RLV-TD

Renewed interest in re-usable launch vehicles has led to the evolution of technology demonstration concepts, where the prime objective is to demonstrate new technologies at reduced cost and shorter turnaround time. This article presents details of both ascent and descent mission design of a low-cost Reusable Launch Vehicle Technology Demonstration (RLV-TD) programme. The technology demonstrator vehicle is boosted to hypersonic Mach number using a solid booster. During ascent phase, the vehicle was flown in a gravity turn trajectory to minimize structural loads on it. In the descent phase, an optimum angle of attack profile as a function of Mach number was computed to limit dynamic pressure, load factor and achieve vehicle trim with minimum control surface deflection. The mission design parameters were evaluated using Monte Carlo analysis utilizing six degrees of freedom simulations. Comparison of actual flight performance with pre-flight prediction is also made this article. Flight performance exhibits close match with the pre-flight predictions.

Integrated Electrohydraulic Control Actuation System with Centralized Power Plant for the Reusable Launch Vehicle Technology Demonstrator

An electrohydraulic control actuation system for actuating eight aerodynamic control surfaces of the two-stage technology demonstrator of the Indian reusable launch vehicle (RLV-TD) was developed, validated by extensive testing in various test beds, simulation runs and flight proven in the RLV-TD HEX-01 mission flight on 23 May 2016. A centralized hydraulic power generating unit (HPU) was used for powering the eight actuators located in two stages. The network of plumbings and control components of this actuation system were required to be laid out over the entire length and breadth of the vehicle measuring 17 m in length, to distribute the hydraulic power to all the actuators. The hydraulic actuation system had to work for the longest ever duration of 833 s for an Indian launch vehicle. Many challenges arose due to a single HPU for two stages, long complex network of plumbings, longest ever operating duration, thermal issues, second-stage structure resembling an aircraft, limited occupancy for operations at the launch pad, limited power source, etc. Necessary provisions were incorporated in the design to successfully overcome them. This article describes the development of the control actuation system.

An Overview of Reusable Launch Vehicle Technology Demonstrator

After the successful operationalization of Polar Satellite Launch Vehicle and Geo Synchronous Launch Vehicle, the Indian Space Research Organisation is in the process of developing Reusable Launch Vehicle technologies to achieve low-cost access to space. Towards this programme, a winged body configuration was conceived, which can fly at subsonic, supersonic and hypersonic Mach number regime, re-enter into the earth’s atmosphere and simulate the landing manoeuvre. The aerodynamic design, analysis and wind-tunnel testing, aerothermal and structural design, analysis and testing were carried out. Suitable solid motor with slow burn rate propellant was developed. Mission design, guidance and control schemes were implemented. In order to meet the above objectives, certain technologies and infrastructure were developed. The entire subsystems were integrated and a large number of flight measurements were made in the maiden successful flight of Reusable Launch Vehicle Technology Demonstrator in May 2016. The flight measurements and flight performance indicated that the design philosophy, testing schemes and approaches followed are in order, thus providing confidence to proceed to the next logical step in the development of Reusable Launch Vehicle Technologies.

Special Theme: India’s Reusable Launch Vehicle Technology Demonstrator: The Future of Space Transportation System

Special Theme: India’s Reusable Launch Vehicle Technology Demonstrator: The Future of Space Transportation System

Design, Analysis and Qualification of Elevon for Reusable Launch Vehicle

Reusable launch vehicle technology demonstrator is configured as a winged body vehicle, designed to fly in hypersonic, supersonic and subsonic regimes. The vehicle will be boosted to hypersonic speeds after which the winged body separates and descends using aerodynamic control. The aerodynamic control is achieved using the control surfaces mainly the rudder and the elevon. Elevons are deflected for pitch and roll control of the vehicle at various flight conditions. Elevons are subjected to aerodynamic, thermal and inertial loads during the flight. This paper gives details about the configuration, design, qualification and flight validation of elevon for Reusable Launch Vehicle.

Quality Assurance and T&E of Inertial Systems for RLV Mission

This work describes the quality assurance and Test and Evaluation (T&E) activities carried out for the inertial systems flown successfully in India’s first reusable launch vehicle technology demonstrator hypersonic experiment mission. As part of reliability analysis, failure mode effect and criticality analysis and derating analysis were carried out in the initial design phase, findings presented to design review forums and the recommendations were implemented. T&E plan was meticulously worked out and presented to respective forums for review and implementation. Test data analysis, health parameter plotting and test report generation was automated and these automations significantly reduced the time required for these activities and helped to avoid manual errors. Further, T&E cycle is optimized without compromising on quality aspects. These specific measures helped to achieve zero defect delivery of inertial systems for RLV application.

Inverse Flush Air Data System (FADS) for Real Time Simulations

Flush Air Data Sensing System (FADS) forms a mission critical sub system in future reentry vehicles. FADS makes use of surface pressure measurements from the nose cap of the vehicle for deriving the air data parameters of the vehicle such as angle of attack, angle of sideslip, Mach number, etc. These parameters find use in the flight control and guidance systems, and also assist in the overall mission management. The FADS under consideration in this paper makes use of nine pressure ports located in the nose cap of a technology demonstrator vehicle. In flight, the air data parameters are obtained from the FADS estimation algorithm using the pressure data at the nine pressure ports. But, these pressure data will not be available, for testing the FADS package during ground simulation. So, an inverse software to FADS which estimates the pressure data at the pressure ports for a given flight condition is developed. These pressure data at the nine ports will go as input to the FADS package during ground simulation. The software is run to generate the pressure data for the descent phase trajectory of the technology demonstrator. This data is used again to generate the air data parameters from FADS algorithm. The computed results from FADS algorithm match well with the trajectory data.

Instrumentation and Baseband Telemetry for RLV-TD HEX Mission

In this work, the salient requirements and features of the baseband telemetry system used in Reusable Launch Vehicle—Technology Demonstrator Hypersonic Experiment mission are discussed. The configuration of the overall system, subsystem components and their features are described in brief. The unique requirements of the telemetry system, when compared to that in a conventional launch vehicle, by way of a large number of temperature and strain measurements that enable the assessment of structural integrity and mission performance in re-entry mission, are dealt with, along with the system configuration to cater to these. Subsequently, two new units have been described—Strain Data Acquisition Unit and Multiplexed Data Acquisition Unit that were inducted specifically to cater to strain measurements using strain gauges and temperature measurements using thermocouples respectively. The optimized subsystem configurations for these units are described and their field performance during flight is analyzed. This work further discusses a novel method of data recovery for those measurements affected by the baseline offset shift caused by the presence of a chassis voltage and poor isolation of sensor to chassis.

Entry guidance with smooth drag planning and non-linear tracking

A guidance strategy is developed for the entry phase, meeting range requirements while honouring the constraints on heat flux, dynamic pressure and structural load on the vehicle. Space shuttle guidance is taken as the baseline and an improved strategy to plan and track a reference drag acceleration profile is developed. Trajectory planning is done in drag-energy plane. Drag acceleration and its derivatives are stored as function of specific energy. An analytical, continuous drag modulation strategy is developed for generating the reference trajectory on-board honouring the constraints. The modulated reference trajectory is tracked by a non-linear controller using Incremental Non-linear Dynamic Inversion technique (INDI). The guidance scheme is demonstrated in a short-range re-entry technology demonstrator vehicle. Simulation studies are carried out to establish the robustness of the guidance algorithm for a wide range of performance dispersions.

Novel Hybrid Yarn Textile Thermoplastic Composites for Function‐Integrating Multi‐Material Lightweight Design

Future mobility applications are characterized by a high level of resource efficiency due to the application of novel lightweight materials and function‐integrating, multi‐material design concepts. Textile thermoplastic composites in particular pave the way for lightweight components characterized by highly specific mechanical properties and efficient production processes. This essay presents the strategy pursued by the Collaborative Research Centre SFB 639 “Textile‐reinforced composite components for function‐integrating multi‐material design in complex lightweight applications”, a concept for the holistic analysis of complex process chains for hybrid yarn textile thermoplastic (HYTT) composites and the idea behind the innovative FiF electric mobility technology demonstrator vehicle.

Evolution of attitude control law of an Indian re-entry launch vehicle

Reusable launch vehicle (RLV) is a goal pursued by different aerospace agencies, world-wide. Indian space research organization is also one among them. This paper covers the challenges faced and the solutions developed for control law design of a typical re-entry vehicle. The first stage of the test vehicle, used for technology demonstration mission, is a conventional solid rocket motor. The second stage of the test vehicle is a winged body vehicle termed as technology demonstrator vehicle (TDV). This TDV forms the orbiter stage of a conceptual two-stage-to-orbit vehicle. While developing control law for TDV, the experience gained in developing control law for expendable launch vehicles is fully utilized. Due to the presence of winged-second-stage, the solution for attitude control problem naturally inherits the procedure and technology used for designing control law of an aircraft. There are significant differences a re-entry vehicle has in comparison to both aircraft and launch vehicles. Due to these differences, the final control law depends on both aircraft and launch vehicle control law design methodologies. In this paper the authors share the insights gained in control law design of a RLV. The paper gives the reasons for the selection of a combination of co-ordinate systems, for the development of linear plant model of RLV. It emphasizes the difference in the plant modelling with respect to aircraft dynamics in accounting gravitational force in the linear plant model. Requirement of pseudo trim condition for force balance is described in the paper. The paper highlights the commands to be tracked and variables to be fed back during different regimes of re-entry flight. Issues in control law gain design with respect to selected sensors and their placement are elaborated in the paper. Insights on the aspect of trim scheduling, gain scheduling, and finalization of control law structure are also given in the paper.

Nanospintronics Based on Magnetologic Gates

We present a seamless integration of spin-based memory and logic circuits. The building blocks are magnetologic gates based on a hybrid graphene/ferromagnet material system. We use network search engines as a technology demonstration vehicle and simulate a high-speed, small-area, and low-power spin-based circuit.

Methods for control of UGV convoys in unexplored and partially unpaved terrain

Under lab conditions various autonomous behaviors are realized and simulated today, but there is still a long way to everyday applications using these capabilities. Therefore this paper will describe our current research results under competition conditions where, in opposite to presentations or test runs for validation and detailed analysis of algorithms, not everything is planable in advance. We will describe the importance of robustness and intuitive control panels, as well as the “follow the leader„ capabilities of our technology demonstration vehicle, using different levels of autonomy, starting from direct control through teleoperation, finally to fully autonomous terrain-based optimized following. This will bring us to the description of adaptive robot control, where the method for robot control depends on the terrain, the mission, and the availability of supervision by a human operator. Therefore several underlying technologies have been extended or newly developed directly, like an specific A* algorithm, that considers non-holonomic constraints and some basic researches on global optimization methods, like mixed integer programming, and its combination with local reactive collision avoidance methods like VFH+ or Fuzzy Systems.

Unmanned space vehicle technology demonstrator

The unmanned space vehicle (USV) program has been undertaken by the Italian Center for Aerospace Research with the aim of developing flying test beds of next generation reentry launch vehicles. In this framework, the development of small demonstrators is also foreseen to validate technological and operational aspects of full-scale vehicles and missions. In this paper, a small-scale demonstrator of the sub-orbital re-entry test mission of the USV program is described. Both mission profile and objectives are very challenging in terms of demonstrator guidance, navigation and control. After a short description of the mission and demonstrator architectures, particular emphasis is given to the guidance and navigation analysis. To this end, mission objectives and reduced-scale system constaints are integrated and translated into innovative guidance solutions relying on optimization techniques. Then, performance of a commercial-off-the-shelf GPS-aided, miniature inertial navigation system over the proposed trajectories is evaluated by Monte Carlo analysis. Standalone inertial and GPS-aided inertial navigation performance is also compared considering GPS loss conditions due to antenna plasma effects.

Adaptive state of charge algorithm for nickel metal hydride batteries including hysteresis phenomena

A state of charge (SOC) algorithm is described and implemented for a nickel metal hydride (NiMH) battery system. The essential elements of the algorithm were first used as part of the GM Precept hybrid electric vehicle program, which culminated in an 80-mile-per-gallon, 5-passenger, technology-demonstration vehicle. The algorithm is based on a simple equivalent-circuit representation of the battery pack, with the parameters adapted by means of on-line least-square regression. The output of the algorithm is the SOC, which is a measure of the available energy within the battery system, and the power capability for subsequent charge or discharge, which enables efficient hybrid vehicle operation through optimal torque allocation. The behavior of the algorithm in terms of convergence, accuracy, and robustness is examined; for these analyses, the power required from the battery for the Precept to complete a variety of drive schedules provides the power versus time trace. Voltage hysteresis is shown to play a critical role, and this effect makes determining the SOC particularly difficult for NiMH batteries relative to other battery systems (e.g., lead acid and lithium ion).

An all-electric vehicle technology demonstrator with a 35-mm electrothermal gun system

Within the German R&D programmes on the application of electrical energy for all main subsystems within a battle field tank, electric drive and electric firing have already been independently demonstrated successfully. The performance of an electric drive system has been demonstrated successfully based on a MARDER 1 chassis as well as on a 8/spl times/8 wheel chassis. The performance of electric gun systems has been investigated extensively using laboratory setups. For a next step the integration of the different technologies into a mobile demonstrator with the incorporation of all electric systems is proposed. The paper gives the results of a first conceptual study. Based on a MARDER 1 chassis the different subsystems have been specified and first layouts due to the technology status were generated in detail. These subsystems are: electric drive, 2-MJ capacitive pulsed power, 35-mm repetitive firing electrothermal gun. An integration concept of the different subsystems into the chassis is described.