Hands-free robotic leg massage device
Therabot arrived with a proof-of-concept prototype from a previous engineering team: functional, but large, bulky, and far from a product. We redesigned everything from the inside out. New motor architecture, new mechanical system, new internal layout, new exterior form. The result is a compact, production-ready device built entirely by SLIMDESIGN.
Challenge
A previous engineering team had proven the core concept: a motorised ring that wraps the leg, applies rolling pressure, and travels from ankle to thigh without any effort from the user. The prototype worked. It was also large, bulky, and visually intimidating. It communicated industrial machinery, not a consumer product. The task was to keep what was proven and rebuild everything else.
Approach
We started with motor selection, since the motor choices in the original device were the main driver of its bulk. A new configuration, optimised for torque, form factor, and continuous duty, unlocked a significantly smaller chassis. From there we redesigned the full mechanical architecture, developed the exterior from scratch, and built all electronics, firmware, and software in parallel.
Result
We delivered visual and functional prototypes built entirely from our own mechanical, electronic, and software work, with full production implementation support. The device is a fraction of the size of the original prototype, with a coherent exterior and validated product ecosystem. Therabot is in pre-order with the first 1,000 units shipping September 2026, priced from $499 to $749. The dual-motor architecture is covered by a pending patent.
Redesigned From The Inside Out
The size of the original prototype was largely driven by its motor selection. We evaluated multiple motor configurations, comparing torque, size, thermal performance, and duty cycle requirements to identify a solution that could deliver the necessary contact force within a much smaller package. This decision was key to reducing the overall size of the device.
The system uses separate motors for its two primary functions. Tension motors adjust the chassis to apply pressure against the leg, while drive motors integrated into the rollers move the device along the body. Separating these functions allowed each system to be optimized independently for performance and control.
Chassis Tension Motors
Roller Drive Motors
User Testing
Every prototype was put on a leg. Pressure calibration, travel speed, roller contact across the knee, and battery endurance were all validated on real users before any parameter was locked. Force output was measured at multiple leg diameters to confirm the pressure calibration held across the full range of users. Travel consistency was tested across sessions, checking that the device tracked straight and returned cleanly to the start position without manual correction. Roller profiles were evaluated back to back on the same tester to isolate the sensation difference between variants. What works on a bench does not always work on a body, and the testing programme was designed to surface that gap as early as possible.
Engineering & Electronics
Hardware and software ran in parallel rather than in sequence. Mechanical changes fed immediately into the electronics and vice versa. SLIMDESIGN was responsible for the overall PCB layout strategy, including the definition of key component placement and critical footprint. We led the motor and sensor integration, and worked closely with the firmware development team to optimize system performance and control algorithms.
Form Exploration And Prototyping
Therabot User Stories
If you are exploring a new product or facing complexity in development,
we are happy to discuss your situation and identify the most effective next step.