Senior Mechanical Engineer- Arm

At Rhoda AI, we’re building the next generation of generalist intelligent robots. We own the full robotics stack from high-performance hardware and robot systems to the infrastructure and state-of-the-art foundation world models that control our robots. Our robots are designed to be generalists capable of operating in complex, real-world environments and handling long-tail edge cases, made possible by our cutting edge research and end-to-end system design. We've raised over $450M and are investing aggressively in model research, infrastructure, hardware development, and manufacturing scale-up to make generalist robotics a reality.

We're looking for a Senior Mechanical Engineer to own the upper arm of our humanoid robot platform. The upper arm carries the highest structural loads in the arm chain — it reacts every payload the hand lifts through the shoulder into the torso, houses the largest actuators in the limb, and serves as the trunk through which all power, data, and sensing flow to everything downstream. Working with actuators developed by our dedicated actuation team, you'll own the upper arm end to end: shoulder and elbow joint structures, the interfaces to the torso above and lower arm below, electrical packaging within the limb, and the harness trunk and thermal strategy that support the entire arm. This is a high-ownership role at the structural and electrical convergence point of the platform.

What You'll Do

• Own the design of the upper arm end to end — shoulder and elbow joint structures, links, and housings — making the trade-offs between stiffness, mass, inertia, cost, and manufacturability under the highest structural loads in the arm chain

• Define and own the interface to the torso, including the structural mount, load paths into the frame, alignment and registration features, and the electrical pass-through that feeds the entire arm — driving this interface to closure with the torso team

• Define and own the interface to the lower arm at the elbow, partnering with the lower-arm owner on structural attachment, alignment, connectorization, and serviceability

• Integrate the largest actuators in the limb, working closely with the actuation team on mounting, envelope, cable exits, and heat rejection requirements for the shoulder and elbow

• Own the harness trunk through the upper arm: the main power and data runs feeding the lower arm and hand, routing across the shoulder and elbow joints, service loops, strain relief, connectorization, and bend-cycle durability validated against the platform's full life requirements

• Own the electrical packaging within the upper arm — mounting and enclosing PCBAs and sensor boards in a moving, space-constrained limb, working with the EE team on board outlines, connector placement and access, keep-outs, grounding and shielding provisions, and vibration-tolerant mounting

• Own the thermal design of the upper arm — conduction paths from the limb's highest-power actuators and packaged electronics into structure, thermal interface strategy, and validation under sustained duty cycles — in partnership with actuation and electrical teams

• Participate in FMEAs and define the validation and durability test strategy for the subsystem, and lead root cause analysis when hardware issues arise in the arm

• Create and maintain CAD models, drawings, tolerance stacks, interface control documents, and BOMs through design reviews and manufacturing handoffs

• Plan and execute prototype builds and test campaigns — structural, thermal, and cable-durability — and iterate quickly and rigorously from test results

• Mentor junior engineers and raise the bar on design practices, documentation, and design review rigor across the team

What We're Looking For

• BS in Mechanical Engineering or a closely related field (MS preferred)

• 5+ years of experience in mechanical design of robots, robotic arms, or complex electromechanical products

• Demonstrated ability to make and defend engineering trade-offs — stiffness vs. mass, integration vs. serviceability, performance vs. cost — with quantitative rigor

• Strong experience designing structural components for high-load dynamic systems, including structural analysis correlated to physical test

• Experience defining and driving interfaces with other engineering teams — negotiating requirements and holding designs to them

• Experience integrating high-torque actuators into structural assemblies, including load path design, mounting stiffness, and heat rejection

• Strong hands-on experience with cable routing, harness design, and electromechanical integration in moving mechanisms

• Experience packaging PCBAs and electronics in tightly constrained mechanical envelopes, collaborating with electrical engineers on board outlines, connectors, and mounting

• Solid command of thermal design — conduction paths, thermal budgeting, interface materials, and test-based validation

• Expert-level proficiency with CAD software (Catia, SolidWorks, Fusion 360, Onshape, or similar), including complex assemblies and tolerance analysis

• Deep familiarity with manufacturing processes — machining, casting, sheet metal, 3D printing — and design-for-manufacture principles

• Comfort working hands-on with hardware: building prototypes, running tests, and troubleshooting physical systems

• Strong communication skills and the ability to drive cross-team problems to closure

Nice to Have (But Not Required)

• Experience designing robot arms, manipulators, or other serial-link mechanisms

• Experience with mass and inertia optimization for dynamic limbs or payload-sensitive structures, including topology optimization or structural lightweighting

• Familiarity with high-flex cable selection, continuous-flex ratings, and bend-cycle testing across articulating joints

• Experience designing structural castings or complex machined housings for high-load joints

• Working knowledge of GD&T (ASME Y14.5) applied to precision assemblies, including datum strategy for multi-team interfaces

• Experience with FMEAs, design reviews, or structured reliability programs

• Experience taking a subsystem from concept through DVT/PVT into production

Why This Role

• Own the load-bearing backbone of the arm — everything the robot lifts, carries, and manipulates flows through your structures, and your decisions define the arm's strength, speed, and reliability

• Work at the convergence point of the platform — torso, lower arm, actuation, and electrical teams all meet in the upper arm, and you'll be the engineer who drives those interfaces to closure

• Join at a foundational moment and contribute directly to the physical architecture of a next-generation humanoid robot