Thermal cores on patrol and inspection robots: typical specs, and what to check before you choose one

What published robot payloads use

From the manufacturers’ published specifications (checked October 2026):

• Boston Dynamics Spot CAM+IR: 640 × 512, 69° × 56°, ±5°C, −40 to 160°C (high gain) and −40 to 550°C (low gain)
• ANYbotics ANYmal: 336 × 256, 46°, −40 to 550°C

Resolution runs from 336 × 256 to 640 × 512, fields of view from about 46° to 69°, and measurement up to around 550°C.

Resolution: count pixels on the target

A common rule is that a target needs at least 3 × 3 pixels for a reliable reading. With a 9.1 mm lens on a 640 × 512, 12 μm core (IFOV 1.3 mrad), one pixel at 3 m covers about 3.9 mm, so a target of about 12 mm is enough (calculated). Write down your smallest target (a terminal, a fuse, a bearing housing) and your real distance, then choose resolution and lens together.

Field of view: aisles and cabinets

The width you see is 2 × distance × tan(HFOV / 2). To see a 3 m-wide scene, the camera has to be (calculated):

• About 3.3 m away with 48.7° (9.1 mm lens on 640 × 512)
• About 2.4 m away with 64.1° (4 mm lens on 384 × 288)
• About 1.6 m away with about 88° (4 mm lens on 640 × 512, rectilinear)

In narrow aisles the wide lens wins. For gauges and equipment across a room, the narrower lens puts more pixels on the target. On a radiometric 640 core, wide lenses are non-standard: samples ship within 15 working days of payment.

Temperature range

Equipment heating is normally measured in a low range (−20 to 150°C on this core); hot process equipment needs a high range (100 to 650°C on this core). An open flame is hotter than the top of that range, so treat it as detection, not measurement. Read the accuracy line (±2°C or ±2% typical here, measured by the maker in a lab) as a best case: emissivity, reflections and distance usually matter more on a real target.

Stop, then measure

Uncooled pixels respond with a thermal time constant (under 12 ms on this core), so a moving robot smears its targets. Seen from the side at 3 m with the 9.1 mm lens, a 50 mm target reads about 98% of its real temperature rise at 1 m/s, about 85% at 2 m/s and about 72% at 3 m/s (calculated). A robot that stops at each inspection point avoids the problem.

Close range on arms

Fixed-focus lenses have a near limit. The 9.1 mm lens on this core is sharp from 1.2 to 5.5 m, so an arm that brings the core to 0.5 m from a panel will give a soft image. Ask for the sharp range at your closest distance, and whether a close-focus or manual-focus version is available.

Size, power and software

This core is 21 × 21 × 10.3 mm, under 8.6 g without the lens (the 9.1 mm lens adds 10.5 g), and draws under 0.7 W typical over USB at 25°C, small enough for the end of an arm or a mast. USB into the robot’s computer is the quickest integration. Check that the SDK runs on that computer (often Linux on ARM, such as Jetson or Raspberry Pi), and whether you get a ROS driver or have to write one.

Environment

Measurement on this core is specified for −10°C to +70°C ambient, imaging for −40°C to +80°C. For outdoor patrols in winter, plan a heated enclosure. A bare core has no ingress rating, and the window in front of it must be an infrared material such as coated germanium, never glass.

Before you choose a core

1. Smallest target and working distance: lens and resolution
2. Field of view at your closest working distance
3. Temperature range, and how you will handle emissivity
4. Stop to measure, or measure on the move
5. SDK and drivers for the robot’s own computer
6. Ambient range, housing and window

View MINI 640-2 Radiometric