ONHUMAN is an AI robotics company developing autonomous general-purpose humanoid robots. Our goal is to build embodied AI systems that can perceive, reason, and act in the real world. ONHUMAN is headquartered in Madrid, Spain, and this role requires 5 days/week in-office collaboration.

Team & Role Overview

Our Hardware Engineering team is responsible for developing the physical architectures, advanced mechatronics, and structural foundations that house humanoid autonomy. We are looking for a Senior Mechanical Engineer to design, optimize, and advance the core mechanical systems, high-torque actuators, and structural kinematics that enable fluid, human-like motion in the real world.

This role focuses on developing cutting-edge physical approaches across robot mechanics—spanning lightweight structural design, custom cycloidal/harmonic geartrains, thermal management, and dynamic load distribution—directly impacting the agility, payload capacity, and physical reliability of our humanoid platforms.

Responsibilities

• Mechanical Architecture Design: Design and develop high-performance mechanical systems and structural layouts across the humanoid robot frame (e.g., limbs, torso, hands, and joints).

• Actuation & Mechatronic Integration: Build and optimize high-torque density actuator assemblies, integrating custom BLDC motors, geartrains, position sensors, and structural bearings.

• Kinematics & Structural Dynamics: Advance structural modeling, structural finite element analysis (FEA), and multibody dynamics to maximize rigidity while aggressively minimizing moving mass.

• Thermal & Environmental Capability: Improve thermal dissipation systems and environmental sealing (IP ratings) to ensure reliable robot operation across long-horizon missions and diverse real-world environments.

• End-to-End Product Lifecycle: Work across the entire hardware lifecycle, from initial CAD conceptualization, kinematics scripting, and structural prototyping to production-intent sourcing and assembly.

• Cross-Functional Fusion: Collaborate closely with electrical engineering, controls, simulation, and RL teams to integrate structural mechanics seamlessly with low-latency actuators and whole-body control stacks.

• Experimental Rigor & Testing: Design structural stress-testing experiments, lifecycle endurance rigs, and environmental evaluation frameworks to characterize mechanical behavior and guide physical iteration.

• Contribute to New Paradigms: Contribute to the development of next-generation robotic hardware paradigms, driving innovations in custom mechatronics, lightweight alloys, and composite materials.

Requirements

• Advanced Mechanical Design Experience: Proven experience designing, analyzing, and shipping complex, high-performance mechatronic systems, moving mechanisms, or dynamic hardware platforms.

• Mastery of CAD & FEA: Deep proficiency in modern 3D CAD modeling environments (e.g., SolidWorks, NX, or Creo) and advanced simulation software for finite element analysis (structural, modal, and thermal).

• Deep Actuation & Component Knowledge: Strong understanding of high-performance transmission systems (harmonic drives, cycloidal gears, planetary sets), bearing configurations, and precision machining tolerancing (GD&T).

• Material Science Literacy: Excellent understanding of engineering materials (aluminum, titanium, carbon fiber composites, plastics) and their manufacturing methods (CNC machining, injection molding, casting, 3D printing).

• Experimental & Analytical Rigor: Strong technical rigor, a data-driven approach to mechanical debugging, and the ability to systematically diagnose physical failures or backlash in mechanical linkages.

• Systems Engineering Mindset: Solid documentation and organization skills with the ability to maintain clean bills of materials (BOMs), assembly documentation, and manufacturing handoff specifications.

• Autonomy & Ambiguity: Ability to operate independently and drive elegant, lightweight solutions into highly complex, ambiguous physical constraints.

Bonus Qualifications

• Humanoid or Mobile Robotics Background: Direct experience designing humanoid legs, multi-axis robotic arms, agile quadrupeds, or highly dynamic automation mechanisms.

• Custom Actuator Design: Background designing custom electric actuators from scratch, including custom coil layout considerations, magnet rotors, and integrated strain gauges.

• Dynamic Physics & Control Familiarity: Basic understanding of robotic control systems, torque loop feedback, or multi-joint rigid body dynamics (URDF modeling).

• Frontier Hardware Scaling: Experience working at fast-scaled, capital-intensive hardware startups, aerospace companies, autonomous vehicle labs, or elite advanced manufacturing centers.

Compensation

The pay offered for this position may vary based on several individual factors, including job-related knowledge, skills, and experience. The total compensation package may also include additional components/benefits depending on the specific role. This information will be shared if an employment offer is extended.