High-power, null-type, inverted pendulum thrust stand.

Area of Science:

• Aerospace Engineering
• Propulsion Systems
• Measurement Science

Background:

• Accurate thrust measurement is critical for spacecraft propulsion system development and validation.
• Traditional thrust stands can suffer from alignment errors and mechanical oscillations, impacting measurement precision.
• Existing designs may not adequately address thermal effects or provide integrated calibration capabilities.

Purpose of the Study:

• To present the theory and operation of a null-type, inverted pendulum thrust stand.
• To design a thrust stand capable of measuring thrust from 1 mN to 5 N for thrusters up to 250 kg.
• To achieve high measurement accuracy by minimizing alignment errors and actively damping oscillations.

Main Methods:

• Utilized a null-type inverted pendulum design to enhance sensitivity and eliminate thrust alignment errors.
• Implemented a feedback control system where thrust stand position is the input and actuator current is the output.
• Incorporated an electromagnetic damper for active oscillation damping, a closed-loop inclination system for leveling, and an active cooling system.

Main Results:

• Successfully measured the thrust of a 3.4 kW Hall thruster up to 230 mN.
• Achieved a thrust measurement uncertainty of +/-0.6%, validated through analysis of hysteresis, zero-offset drift, and calibration slope variation.
• The thrust stand design supports thrusters with a total mass up to 250 kg.

Conclusions:

• The developed null-type inverted pendulum thrust stand offers a sensitive and accurate method for measuring low-thrust propulsion systems.
• The integrated features, including active damping, leveling, cooling, and in situ calibration, contribute to reliable and precise thrust measurements.
• The achieved uncertainty of +/-0.6% demonstrates the effectiveness of the design for critical spacecraft propulsion testing.