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 and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts. This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact. 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

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. Benefits And Perks All full-time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company-paid holidays, and comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day. While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government–issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance. Affirmative Action/EEO Statement Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.