Building a Wireless Charger That Never Misses
Summary: Wireless charging often fails due to misalignment, leading to uncharged battery devices overnight. HTX Studio solved this by designing a desk equipped with a 2-axis robotic mechanism and overhead vision tracking, automatically moving the charging transmitter directly beneath wherever a user places their phone.
Key Takeaways
- Dynamic Positioning: Instead of forcing the user to precisely place their phone, the desk moves the wireless charger beneath the desk surface to meet the phone.
- 2-Axis Plotter Mechanism: The system relies on stepper motors, lead screws, and an Arduino to move the charging coil across XY coordinates under the desktop.
- Overhead Vision Tracking: An overhead camera uses computer vision or object recognition to locate devices on the desk and trigger movement.
Detailed Overview
Wireless smartphone charging is convenient in theory, but in practice, slight misalignments frequently lead to missed charges. Rather than abandoning wireless charging altogether, HTX Studio built a custom desk that solves the alignment problem entirely by motorizing the charging element.
The underlying concept is simple: instead of requiring the user to align their device with a fixed charging pad, the system moves the charger to the device wherever it is set down on the desk surface.
Mechanized Under-Desk Motion System
To implement this functionality, HTX Studio developed a physical motion system mounted beneath the desk surface.
The mechanism is built around a two-axis motion system, operating similarly to a standard pen plotter:
- Actuation: Stepper motors rotate lead screws to drive linear movement along the X and Y axes.
- Control Unit: Stepper motor drivers feed power to the motors under the direct control of an Arduino board.
- Coil Assembly: The wireless charging transmitter moves smoothly along the underside of the tabletop to align directly with the detected coordinates.
Deep Dive & Technical Insights
To determine where to dispatch the internal charger, the system relies on real-time device tracking above the workspace.
- Location Detection: An overhead camera monitors the surface of the desk, leveraging object recognition models or computer vision to identify the presence and exact position of a device.
- Sequential Multi-Device Charging: The mechanism can travel between multiple target devices placed on the desk—such as alternating between an iPhone and an AirPods case.
- Integrated Desk Features: Beyond wireless charging, the desk integrates several additional custom components:
- Built-in display screen for graphics and feedback.
- Integrated Mac Mini mounted inside the desk chassis.
- Motorized height adjustment system.
Conclusion & Resources
By merging computer vision with microcontroller-driven mechanical motion, HTX Studio turned a passive piece of furniture into an active, automated desk that eliminates the key usability flaw of wireless charging.