| 1. |
- Johansson, Christoffer, et al.
(författare)
-
Improving the Control Design of the KNATTE Platform with Flexible Panels
- 2022
-
Ingår i: IAC 2022 Congress Proceedings, 73rd International Astronautical Congress (IAC), Paris, France. - : International Astronautical Federation.
-
Konferensbidrag (refereegranskat)abstract
- The effect of flexible structures such as solar panels or long booms on the dynamics of a spacecraft of any size can become a problem for the stability of its control subsystem. That said, proper control algorithms can be designed to reduce the vibrations of such appendages. The Kinesthetic Node and Autonomous Table-Top Emulator (KNATTE), developed at Luleå University of Technology in collaboration with the University of Rome “La Sapienza”, is a frictionless vehicle that has been conceived as a multipurpose platform to perform hardware-in-the-loop simulation experiments with real and analogous small-satellite components. The platform can emulate spacecraft behavior in orbit for validating various guidance, navigation and control algorithms.The object of this study is the KNATTE platform carrying a pair of flexible mock-up solar panels. In such circumstances, the steering system of the vehicle is not able to maneuver by applying a conventional Proportional-Integral-Derivative control algorithm. However, a Linear-Quadratic-Gaussian (LQG) algorithm has been proven effective to control the vehicle with the appendages in former simulations. The purpose of this work is to validate the performance of the previously developed LQGalgorithm in a hardware-in-the-loop simulation experiment and compare its results to those of applying a Sliding Mode Control (SMC) algorithm to the same scenario.This article presents a comparative study of the LQG and SMCalgorithms. For that, both algorithms have been developed in Simulink and tested in equivalent modeled environments. Next, the algorithms have been adapted to the operation of KNATTE for their validation on hardware, includingadditional modifications to the experiment setup when necessary. The tracking data coming from a computer vision system has been filtered to improve the accuracy of the navigation block. The signal conditioning circuit has also been upgraded to improve the reliability of panel deflection measurements given by piezoelectric sensors.Both the LQG and SMC algorithms proved to be effective to reduce the destabilizing vibrations of the flexible panels and their suitability for controlling the KNATTE platform with such panels despite their dependency on an accurate model of the plant. The SMC algorithm showed less error than the LQG algorithm in the tested scenario. Additionally, the implementations in this work can be used for future educational and research experiments with frictionless platforms.
|
|
| 2. |
- Lundström, Lars, et al.
(författare)
-
A Multisensor Data Fusion Approach for Spacecraft Control Experiments with the KNATTE Platform
- 2022
-
Ingår i: IAC 2022 Congress Proceedings, 73<sup>rd</sup> International Astronautical Congress (IAC), Paris, France. - : International Astronautical Federation.
-
Konferensbidrag (refereegranskat)abstract
- The Kinesthetic Node and Autonomous Table-Top Emulator (KNATTE) is a three-degree-of-freedom frictionlessvehicle that serves as a multipurpose platform for real-time spacecraft hardware-in-the-loop experiments. The dataacquisition of the vehicle depends on a Computer Vision System (CVS) that yields position and attitude data, but alsosuffers from unpredictable blackout events. To complement such measurements, KNATTE incorporates an InertialMeasurement Unit (IMU) that yields accelerometer, gyroscope, and magnetometer data. This study describes amultisensor data fusion approach to obtain accurate attitude information by combining the measurements from theCVS and the IMU using nonlinear Kalman filter algorithms. To do this, we develop the data fusion algorithms andtest them in a MATLAB/Simulink environment. After that, we adapt the algorithms to the KNATTE platform andconfirm the performance in various conditions. Through this work, we can check the accuracy and efficiency of theapproach by numerical simulation and real-time experiments.
|
|
| 3. |
- Ramavaram, Harish Rao, et al.
(författare)
-
Preparing for Beyond-LEO Nano-Satellite Missions : Benefits of New GNC Strategies
- 2022
-
Ingår i: IAC 2022 Congress Proceedings, 73rd International Astronautical Congress (IAC). - : International Astronautical Federation, IAF.
-
Konferensbidrag (refereegranskat)abstract
- Until very recently, CubeSat class small satellite missions were restricted to Low Earth Orbit (LEO) applications. The launch and success of Mars Cube One (MarCO) twin CubeSats in 2018 opened a new paradigm of planetary exploration using these low-cost platforms. Consequently, there are over 50 beyond LEO small satellite missions that have been planned over the next 5 years. The primary objective of this paper is to investigate the current Guidance Navigation Control (GNC) capabilities of CubeSat class satellites speci cally in the context of planetary exploration and identify techniques and strategies that could potentially improve the utilisation of existing hardware as part of an ongoing research project at Lule a University of Technology in preparation for upcoming beyond LEO nano-satellite missions. Traditional GNC techniques such as ballistic propulsion and ground-based navigation do not scale well for small satellites as the former requires prohibitively large amounts of chemical propellant and the latter requires extensive ground-based infrastructure which increases the operational cost drastically. Fortunately, recent advances in electric propulsion and autonomous navigation techniques such as opti- cal and crosslink radiometric navigation broadened the feasibility of deep space CubeSat missions. The current paper discusses the state-of-the-art of each of the above GNC techniques while proposing archi- tectures that could bene t from the above techniques. The paper also provides an overview of various GNC strategies that are being considered for the planned beyond-LEO small satellite missions.
|
|
| 4. |
- Sarille Cadenas, Carlos, et al.
(författare)
-
Project APTAS - Development of a 1U CubeSat payload for independent calibration and testing of EISCAT3D
- 2022
-
Ingår i: IAC 2022 Congress Proceedings, 73<sup>rd</sup> International Astronautical Congress (IAC), Paris, France. - : International Astronautical Federation.
-
Konferensbidrag (refereegranskat)abstract
- There are many interesting aspects of Earth’s upper atmosphere and near space environment to study. The 3D radar developed and built by EISCAT (EISCAT3D) will expand these possibilities and become a powerful tool to study these phenomena.Industry collaboration between universities and start-ups or traditional companies can provide opportunities to mitigate this challenge, and often spark new technologies or innovative ways to utilize current technologies for new ventures. Therefore, Luleå University of Technology’s first CubeSat (APTAS) has been working in co-operation with EISCAT to develop a payload to perform independent, redundancy testing for the radar system.The payload will provide the ability to perform an independent form of testing for EISCAT3D. To achieve this, APTAS’ very high frequency antenna will send a predefined signal to the instrument. The received signal will be compared to its predicted value, allowing studies of how the instrument performs. Since normal satellite function uses the ultra-high frequency band, the operation of the payload will not interfere with other satellite activities.Due to the fact that APTAS’ main scientific objective is Earth observation, a significant portion of the 1U satellite was allocated to camera optics. Because of this, a traditional board did not fit, since the optics dominate most of the satellite’s internal space. The solution was to adapt the payload board to fit around the camera lens, which was made possible by an in-house, custom fitted design based on APTAS’ unique geometrical restraints.This paper will discuss in detail the development and manufacturing of this payload and more broadly how development of small-sat payloads can be designed, built, and managed by student organisations. In addition, the paper will cover the challenges attributed to the development of a student-led CubeSat and corresponding recommendations for possible improvements. Finally, the importance of proper and thorough documentation within a project involving a high rate of member rotation and quick development will be further highlighted.
|
|
