HIL Test Engineer

Mill • San Bruno, CA

1d • $165,000 - $185,000

About The Position

Mill is a waste prevention technology company developing systems and infrastructure that help keep food scraps out of landfills and in the food system. Its Mill Commercial product is an end-to-end solution for managing, understanding, and preventing food waste in commercial environments.

Mill is hiring a Hardware-in-the-Loop (HIL) Test Engineer to own the test station for the Mill Commercial program, including its hardware, sensor and actuator emulation, and plant models. The role covers systems that emulate safety interlocks, load cells, motor feedback, thermocouples, and heater elements. This is a hands-on build-and-maintain position: the engineer will support vendor commissioning, bring the station into operation, extend its capabilities, develop and tune Simulink models, and implement automated tests in CI. The engineer will work closely with Firmware, Systems, Test Engineering, EE, and SW QA, and will debug results 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 to understand firmware control logic, test coverage, and failure origins.
• Comfort with signal-level work involving thermocouples, strain gauges, hall-effect and discrete inputs, PWM drive lines, and the I/O modules used to emulate them.
• Practical bench skills, including wiring, harness building, and oscilloscope and DMM work.
• Experience with test automation, including scripting test sequences, programmatic pass/fail, results logging, and regression-pipeline integration.
• Strong documentation and organizational skills.
• Clear, direct communication skills, including writing test cases others can run 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 automation APIs such as ASAM XIL, Python-based test frameworks, or 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, establishing 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 and maintain Simulink plant models for oil-jacket thermal behavior, air heater and airflow, vessel cool-down, and grinder load torque; correlate models against real-device data.
• Extend the rig as the test plan grows by adding emulation channels, fault-injection paths, and timing capture.
• Translate engineering and safety requirements into automated HIL test cases with programmatic pass/fail, and integrate them into the Linux-based CI regression.
• Debug failures across the rig, plant model, and firmware, partnering 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 a requirements-based test plan 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