HIL Test Engineer

Mill • San Bruno, CA

19h

About The Position

Mill is a waste prevention technology company that builds systems and infrastructure for homes, businesses, and municipalities to turn food scraps into valuable resources. The HIL Test Engineer will own the hardware-in-the-loop test station for Mill Commercial, including its hardware, sensor and actuator emulation, and plant models. The role covers systems such as safety interlocks, load cells, motor feedback, thermocouples, and heater elements.

This is a hands-on build-and-maintain role. The engineer will take the station from vendor commissioning to an operational bench, extend it with new channels and fault-injection paths, develop and tune thermal and torque plant models in Simulink, and convert engineering requirements into automated tests that run in CI. The role works closely with Firmware, Systems, Test Engineering, EE, and SW QA, and is responsible for understanding test outcomes at the signal level.

Requirements

• At least 4 years of experience in test, controls, or systems engineering on electromechanical products.
• At least 2 years of hands-on experience with HIL or real-time simulation rigs.
• Strong Simulink and MATLAB skills, including building and tuning thermal, mechanical, or electrical plant models and deploying them to a real-time target.
• Ability to read and trace C code and follow firmware control logic to understand test coverage and failure origins.
• Comfort with signal-level work involving thermocouples, strain gauges, hall-effect and discrete inputs, PWM drive lines, and I/O emulation modules.
• Practical bench skills, including wiring, harness building, and oscilloscope and DMM work.
• Strong documentation and organization skills.
• Experience with test automation, including scripting test sequences, programmatic pass/fail, results logging, and integrating tests into a regression pipeline.
• Clear, direct communication skills, including writing runnable test cases and explaining rig behavior to firmware engineers.

Nice To Haves

• Hands-on experience with Speedgoat, dSPACE, NI VeriStand, or similar HIL hardware, including Simulink Real-Time or an equivalent toolchain.
• Experience with Linux-based embedded systems such as Jetson, Yocto, or Debian-class targets, and Linux CI tooling.
• Familiarity with standard automation APIs such as ASAM XIL, or Python-based test frameworks and MQTT.
• Background in safety and interlock testing, fault injection, or functional-safety test methods.
• Experience with thermal or motor-drive systems, including heaters, PID loops, DC motor torque, and current limiting.
• Experience at an early-stage hardware startup, setting up processes rather than inheriting them.

Responsibilities

• Own the HIL test station end to end, including rig hardware, I/O and emulation modules, DUT wiring and harnessing, power and reset control, and surrounding bench equipment.
• Lead vendor commissioning and bring-up, then take ownership of the station in-house after vendor handoff.
• Build, maintain, and correlate Simulink plant models against real-device data, including oil jacket thermal, air heater and airflow, vessel cool-down, and grinder load torque models.
• Extend the rig with emulation channels, fault-injection paths, and timing capture as the test plan grows.
• Translate engineering and safety requirements into automated HIL test cases with programmatic pass/fail, and integrate them into Linux-based CI regression.
• Debug failures to root cause across the rig, plant model, and firmware, working with Firmware and EE to distinguish product defects from test-infrastructure issues.
• Maintain station reliability through calibration, spares, documentation, and a known-good configuration that other engineers can use.
• Partner with SW QA to define test plans based on product requirements and ensure the station can test all cases.
• Partner with Systems and Test Engineering to define the boundary between HIL coverage, bare-board tests, and full-system tests.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed