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A Scalable Tabletop Satellite Automation Testbed:Design And Experiments

Deep Parikh, Ali Hasnain Khowaja, Nathan Long, Ian Down, James McElreath, Aniket Bire, Manoranjan Majji

Abstract

This paper presents a detailed system design and component selection for the Transforming Proximity Operations and Docking Service (TPODS) module, designed to gain custody of uncontrolled resident space objects (RSOs) via rendezvous and proximity operation (RPO). In addition to serving as a free-flying robotic manipulator to work with cooperative and uncooperative RSOs, the TPODS modules are engineered to have the ability to cooperate with one another to build scaffolding for more complex satellite servicing activities. The structural design of the prototype module is inspired by Tensegrity principles, minimizing the structural mass of the modules frame. The prototype TPODS module is fabricated using lightweight polycarbonate with an aluminum or carbon fiber frame. The inner shell that houses various electronic and pneumatic components is 3-D printed using ABS material. Four OpenMV H7 R1 cameras are used for the pose estimation of resident space objects (RSOs), including other TPODS modules. Compressed air supplied by an external source is used for the initial testing and can be replaced by module-mounted nitrogen pressure vessels for full on-board propulsion later. A Teensy 4.1 single-board computer is used as a central command unit that receives data from the four OpenMV cameras, and commands its thrusters based on the control logic.

A Scalable Tabletop Satellite Automation Testbed:Design And Experiments

Abstract

This paper presents a detailed system design and component selection for the Transforming Proximity Operations and Docking Service (TPODS) module, designed to gain custody of uncontrolled resident space objects (RSOs) via rendezvous and proximity operation (RPO). In addition to serving as a free-flying robotic manipulator to work with cooperative and uncooperative RSOs, the TPODS modules are engineered to have the ability to cooperate with one another to build scaffolding for more complex satellite servicing activities. The structural design of the prototype module is inspired by Tensegrity principles, minimizing the structural mass of the modules frame. The prototype TPODS module is fabricated using lightweight polycarbonate with an aluminum or carbon fiber frame. The inner shell that houses various electronic and pneumatic components is 3-D printed using ABS material. Four OpenMV H7 R1 cameras are used for the pose estimation of resident space objects (RSOs), including other TPODS modules. Compressed air supplied by an external source is used for the initial testing and can be replaced by module-mounted nitrogen pressure vessels for full on-board propulsion later. A Teensy 4.1 single-board computer is used as a central command unit that receives data from the four OpenMV cameras, and commands its thrusters based on the control logic.
Paper Structure (27 sections, 8 equations, 14 figures, 2 tables, 4 algorithms)

This paper contains 27 sections, 8 equations, 14 figures, 2 tables, 4 algorithms.

Table of Contents

  1. Introduction
  2. System Dynamics
  3. Configuration of On-board Thrusters
  4. Equations of Motion
  5. Design of Closed-loop Controller
  6. Controllability and Analysis
  7. Desired Closed-Loop Characteristics and Sampling Time
  8. Sampled Data Regulator with Integral and Non-Zero Set-point Feed-forward Terms
  9. Discrete-Time State Space Model
  10. Closed-loop Controller design and verification :
  11. Integral and Non-Zero Set-point Feed-forward Terms :
  12. Fuel Optimal Trajectories
  13. Necessary and Sufficient conditions for an extremal trajectory
  14. Formulation and Solution of Two Point Boundary Value Problem
  15. Incorporation of Constrained Inputs
  16. ...and 12 more sections

Figures (14)

  • Figure 1: Various thruster configurations for the satellite module
  • Figure 2: Tabletop experiment setup and TPODS module
  • Figure 3: Simulation Histories of $x$ and $\psi$ with rise time $T_r$ and settling time $T_s$ requirements for TPODS planar motion with SDR controller. ($T_r$ = 8 sec and $T_s$ = 10 sec for position, $T_r$ = 5 sec and $T_s$ = 8 sec for the orientation)
  • Figure 4: Simulation histories of states, commanded control inputs $T_c$, and actual control inputs T for sinusoidal tracking signal of magnitude $0.2$ m and period of $30$ sec in $x$ and $y$ with SDR controller
  • Figure 5: Simulation Histories of states for sinusoidal input of magnitude $0.2$ m and period of $30$ sec in $x$ and $y$ with PI-NZSP SDR controller
  • ...and 9 more figures