Up-Close with Walter, the Workshop Sentry That Looks Like a Camera and Responds Like a Robot

John Boss needed reliable oversight for a workshop packed with projects still under wraps. Standard internet cameras record events after the fact and offer little in the moment. He chose a different route and built Walter, a workshop sentry meets security robot, instead.

Walter hangs hung from the ceiling on a unique motorized mount, which at first view resembles a high-end pan-tilt security camera. The camera module, lights, and sensors sit in the tiny black shell, but a second look changes everything, as the inclusion of a full-fledged Nerf blaster gives the whole thing personality.

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A geared lazy Susan bearing controls the unit’s movement, allowing it to swivel smoothly in a full circle. Stepper motors control the pan and tilt movements through a pulley and gearing arrangement. A slip ring keeps the cables from twisting or becoming tangled as the joint rotates, while limit switches keep everything under control in either direction. Overall, the movement is relatively rapid and precise.

The Raspberry Pi 5 serves as the Walter’s brain, processing all of the video from the USB camera, running computer vision procedures to detect and track movement, managing network connections, and making major decisions. Meanwhile, an Arduino Nano clone serves as the motor control system, accepting direct orders from the Pi to ensure responsiveness while the Pi works on the vision and logic. An Android tablet combined with a gamepad allows you to control from anywhere while also providing a low-latency visual stream.

When Walter is left to its own devices, it operates in Sentry mode. Motion detection comes in and can even give you notifications, after which computer vision takes over and tracks whatever caused the movement. The camera and mount maintain focus on the subject without requiring human intervention at any point. Voice recognition adds an additional layer of control; a microphone listens for orders or a spoken password to activate or disable the system, and a small USB speaker allows Walter to respond, give a challenge, or send you an alert.

The defensive options are a little more intriguing, as you get two high-intensity LED floodlights that can either flood the area or generate some very blinding glare. A pair of lasers provides a couple of brilliant points of light that are useful for aiming and visual emphasis. Then there’s the Nerf blaster, which can shoot darts under human or automatic control, and the noise alone is enough to deter even the most determined unwanted visitor.

Walter is the real deal, as it watches the room like a standard camera, but also moves, speaks, shines a light, and generally participates when necessary. When not in use, the ceiling mount hides it, and the pan-tilt mechanics and software allow it to cover the entire space. For a maker space with work that isn’t quite ready for public viewing, the system provides an excellent blend of surveillance and active deterrence that seems like it’s on your side rather than simply sitting there looking technological.
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