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arxiv: 2512.06535 · v2 · pith:IS6RFQITnew · submitted 2025-12-06 · 📡 eess.SY · cs.SY

The E-Rocket: Low-cost Testbed for TVC Rocket GNC Validation

Pedro Santos , Andr\'e Fonte , Pedro Martins , Paulo Oliveira This is my paper

Pith reviewed 2026-05-22 12:47 UTC · model grok-4.3

classification 📡 eess.SY cs.SY
keywords rocket testbedthrust vector controlGNC validationlow-cost prototypePID controllermotion captureelectric rocketavionics
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The pith

The E-Rocket provides a low-cost electric platform to validate thrust vector control for rocket guidance, navigation and control.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper introduces the E-Rocket, an electric-powered rocket prototype assembled from commercial components and 3D-printed parts, created to test guidance, navigation and control algorithms that use thrust vector control. The design includes a gimbal with contra-rotating motors to steer thrust and a dual-computer avionics stack that combines PX4 autopilot hardware with ROS 2 software for flexible algorithm use. Indoor tests in a motion-capture arena with a basic PID trajectory-tracking controller produced accurate flight paths. A reader would care because the setup offers an inexpensive physical environment for trying out rocket control ideas before moving to costlier outdoor flights or larger vehicles. If the results generalize, the platform could let more teams iterate on TVC-based GNC methods quickly and safely.

Core claim

The E-Rocket demonstrates that a low-cost assembly of commercial parts, 3D-printed components, and a servo-actuated gimbal with contra-rotating DC brushless motors, paired with PX4 and ROS 2 avionics, can achieve accurate trajectory tracking in indoor motion-capture tests using a baseline PID controller, thereby establishing its suitability as a versatile testbed for rocket GNC algorithms based on thrust vector control.

What carries the argument

The servo-actuated gimbal mechanism with contra-rotating DC brushless motors that supplies thrust vector control to the small electric rocket.

Load-bearing premise

Indoor motion-capture validation with a baseline PID controller on a small electric prototype will translate to useful insights for real rocket GNC under outdoor flight conditions with different dynamics and disturbances.

What would settle it

Outdoor flight tests that measure large drops in trajectory accuracy from wind or scaling effects not observed indoors would falsify the claim that indoor results reliably inform broader rocket GNC validation.

Figures

Figures reproduced from arXiv: 2512.06535 by Andr\'e Fonte, Paulo Oliveira, Pedro Martins, Pedro Santos.

Figure 1
Figure 1. Figure 1: The E-Rocket: Representation of reference frames (red, green, and blue correspond to the x, y, and z axes, respectively). rockets yet lack an accessible testbed for ultimate flight validations (Santos and Oliveira, 2025). Contributions of this work span across various domains. The cost-effective mechanical design, which relies on read￾ily available components, facilitates the replication of the arXiv:2512.… view at source ↗
Figure 3
Figure 3. Figure 3: Gimbal mechanism representation. freedom and completing the TVC gimbal. Each brushless motor can be controlled independently, allowing for the generation of a differential torque on the axis aligned with the thrust vector. This additional actuation input acts mainly on the yaw channel to prevent spinning motion or to actively control the yaw angle. The gimbal mechanism is attached via two arms to a 3D prin… view at source ↗
Figure 4
Figure 4. Figure 4: Proposed software partition for control and offline planning experimentation. Notation of quantities is introduced [PITH_FULL_IMAGE:figures/full_fig_p003_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: State machine governing flight testing phases. [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Linear identification of longitudinal dynamics. [PITH_FULL_IMAGE:figures/full_fig_p005_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: 3D overview of tracking performance. 5. FLIGHT EXPERIMENTS AND RESULTS For validation purposes, the software architecture was implemented onboard the vehicle and provided of tar￾get waypoints to track. These references correspond to fixed-step discretization results of a polynomial trajec￾tory with continuity C 4 , discretized at a constant rate to timestamped coordinates w ∈ R 3×5 containing the position … view at source ↗
Figure 8
Figure 8. Figure 8: Time evolution of states and allocation variables. [PITH_FULL_IMAGE:figures/full_fig_p007_8.png] view at source ↗
read the original abstract

This paper presents the E-Rocket, an electric-powered, low-cost rocket prototype for validation of Guidance, Navigation & Control (GNC) algorithms based on Thrust Vector Control (TVC). Relying on commercially available components and 3D printed parts, a pair of contra-rotating DC brushless motors is assembled on a servo-actuated gimbal mechanism that provides thrust vectoring capability. A custom avionics hardware and software stack is developed considering a dual computer setup which leverages the capabilities of the PX4 autopilot and the modularity of ROS 2 to accommodate for tailored GNC algorithms. The platform is validated in an indoor motion-capture arena using a baseline PID-based trajectory tracking controller. Results demonstrate accurate trajectory tracking and confirm the suitability of the E-Rocket as a versatile testbed for rocket GNC algorithms.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The paper presents the E-Rocket, a low-cost electric-powered rocket prototype for validating TVC-based GNC algorithms. It uses commercially available components and 3D-printed parts with contra-rotating DC brushless motors on a servo-actuated gimbal for thrust vectoring, a dual-computer avionics stack integrating PX4 autopilot and ROS 2, and indoor motion-capture validation with a baseline PID trajectory-tracking controller. Results show accurate tracking and support the platform's suitability as a versatile testbed.

Significance. If the results hold, the E-Rocket supplies an accessible, reproducible hardware platform using off-the-shelf parts and open-source software for indoor GNC testing. This lowers barriers for algorithm development and provides physical motion-capture benchmarks against which controllers can be evaluated, a concrete strength for experimental systems work.

major comments (1)
  1. Validation/Results: The claim of 'accurate trajectory tracking' and suitability for GNC algorithms rests on qualitative demonstration; no quantitative metrics (e.g., RMS position error, peak deviation, or attitude RMSE) or data tables are referenced, weakening the evidential basis for the central inference.
minor comments (2)
  1. Abstract: Specify the commanded trajectory (e.g., hover, straight-line, or figure-eight) and arena size to give readers immediate context for the reported tracking performance.
  2. Hardware/Avionics sections: Clarify gimbal servo bandwidth, motor thrust-to-weight ratio, and exact PX4-ROS 2 message interfaces to aid reproducibility by other groups.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive comment on the validation and results section. We address the point below.

read point-by-point responses

  1. Referee: Validation/Results: The claim of 'accurate trajectory tracking' and suitability for GNC algorithms rests on qualitative demonstration; no quantitative metrics (e.g., RMS position error, peak deviation, or attitude RMSE) or data tables are referenced, weakening the evidential basis for the central inference.

    Authors: We agree that the manuscript would benefit from quantitative support for the tracking performance claims. The indoor motion-capture experiments recorded position and attitude data that can be used to compute RMS position error, peak deviation, and attitude RMSE. In the revised version we will add these metrics, computed over multiple trials, together with a summary table. This will strengthen the evidential basis for the suitability of the E-Rocket as a GNC testbed while preserving the existing qualitative figures. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental validation against external motion-capture benchmarks

full rationale

The paper presents a hardware prototype and reports results from physical indoor tests using a motion-capture system and baseline PID controller. No mathematical derivation chain, fitted parameters, or predictions are claimed; the central claim of suitability rests directly on measured trajectory tracking performance against an independent external reference. This is self-contained experimental work with no reduction of outputs to inputs by construction or self-citation.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The platform uses standard engineering components and established control methods without introducing new theoretical entities, fitted parameters, or unproven axioms beyond basic assumptions of commercial part reliability and indoor test validity.

pith-pipeline@v0.9.0 · 5674 in / 1068 out tokens · 38423 ms · 2026-05-22T12:47:46.583045+00:00 · methodology

discussion (0)

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Reference graph

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