GNC Engineer - Actuation Systems

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. GNC Engineer – Actuation Systems As a GNC Engineer focused on actuation systems at Castelion, you will build the control algorithms, models, and software that turn vehicle commands into precise physical motion. You will own problems across actuator modeling, closed-loop control, system identification, hardware characterization, simulation, and flight integration. Depending on your experience, you may contribute to individual control loops or take ownership of complete actuation systems from requirements and architecture through hardware testing and flight. This role is a strong fit for engineers who enjoy controls, electromechanical systems, hands-on testing, and seeing algorithms directly affect hardware performance. Responsibilities • Design, implement, and tune closed-loop control systems for flight vehicle actuators • Develop position, velocity, force, torque, and current control architectures as required by the actuator system • Model electromechanical actuator dynamics, including motors, transmissions, ball screws, control surfaces, sensors, structural loads, friction, backlash, saturation, and other nonlinear effects • Develop actuator performance requirements and support motor, gearing, sensor, and mechanical hardware sizing • Perform stability, bandwidth, robustness, disturbance rejection, and tracking performance analysis • Develop feedforward, filtering, compensation, anti-windup, command shaping, and other control features to improve actuator performance • Perform system identification and parameter estimation using component, bench, and integrated test data • Build actuator models for high-fidelity vehicle and 6-DOF simulations • Implement control algorithms in embedded flight software and support real-time execution constraints • Develop Software-in-the-Loop (SITL) and Hardware-in-the-Loop (HITL) test environments for actuator validation • Plan and execute hardware characterization and closed-loop actuator testing • Analyze test and flight data to validate models, identify performance limitations, and improve control designs • Work closely with GNC, avionics, embedded software, mechanical, electrical, and test engineers to deliver integrated flight-ready actuation systems Basic Qualifications • Bachelor's degree in Aerospace Engineering, Mechanical Engineering, Electrical Engineering, Computer Engineering, or a related technical field • Strong fundamentals in feedback controls, dynamics, or electromechanical systems • Experience programming in Python, Rust, C/C++, Julia, or a similar technical computing language • Experience analyzing dynamic systems through coursework, research, internships, projects, or professional work • Ability to work effectively across software, electrical, mechanical, and controls disciplines Preferred Skills and Experience • Experience designing and tuning closed-loop control systems for electromechanical or aerospace hardware • Experience with motor control, servo systems, position control, velocity control, force control, or torque control • Experience modeling DC, BLDC, or PMSM motors and their associated drive electronics • Experience with mechanical transmission systems such as gearboxes, ball screws, linkages, or rotary-to-linear mechanisms • Strong understanding of classical control techniques, including loop shaping, gain and phase margin, bandwidth, and frequency-domain analysis • Experience with state-space controls, observers, feedforward control, or disturbance estimation • Experience with nonlinearities including saturation, rate limits, deadband, backlash, friction, hysteresis, and compliance • Experience with system identification and correlation of analytical models against hardware test data • Experience with embedded or real-time control software • Experience with sensors such as encoders, resolvers, current sensors, load cells, or position transducers • Experience with actuator sizing, power requirements, thermal constraints, structural loads, or performance trades • Experience developing simulation models for actuator dynamics and integrating them into larger vehicle simulations • Experience with Monte Carlo analysis, uncertainty analysis, or robustness assessment • Experience with Software-in-the-Loop (SITL) or Hardware-in-the-Loop (HITL) testing • Experience designing or operating test stands and working directly with flight-like hardware • Experience supporting aerospace, robotics, automotive, industrial automation, or other high-performance motion-control systems Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.