Electronically Controlled Resistance Device

You won’t miss your dumbbells. We promise.

Motivation

A single device capable of providing a wide resistance range, compact enough to easily store anywhere, and most important of all, fun to use. Because getting ripped shouldn’t mean turning your living room into a gym.

Anchoring Schemes

Versatile enough to train your entire body without annoying your downstairs neighbors.

User Experience

Simple User Interfaces
  • Increment and decrement weight via pushbuttons
  • Menu to adjust units and volume
  • Operation mode and weight selection displayed on OLED screen
Low Profile Design

The ECORD has a maximum height of 2″, satisfying even your minimalist friends.

Smooth Motion

Thanks to the slotless Axial-Flux Permanent Magnet (AFPM) motor design the cogging torque is eliminated, providing smooth motion while exercising.

Always-On Tension

A persistent gentle tension is always present, spooling the rope in if the handle is unintentionally pulled without any weight selection.  At power-up, the rope is spooled all the way before allowing normal operation.

Audio Feedback
  • Button presses
  • High-velocity warning
  • Over-velocity trigger
  • “Encouragement” while exercising

Safety Features

High-Velocity Warning

Activated when the rope is spooled too quickly, as a warning to slow down during the eccentric phase. Slow eccentric motion has been shown to offer many physiological benefits.

Over-Velocity Trigger

When exceeding the over-velocity threshold, the tension rapidly decreases to the Always-on level, protecting the electronics from excessive heat generation.

Instability Detection

Unintentionally stepping off the platform mid-rep can cause the ECORD to jerk up. Luckily it can detect this and rapidly drop the tension to the Always-on level, protecting you, your dry wall and your ego.

Linear Tension Ramp-Up

As the handle is pulled, tension increases linearly until full weight is applied at 6” of pull length.

  • Prevents full force from being applied to rope-stop.
  • Keeps power consumption low when weight is selected but device sits idle.

ECORD
Motor

The custom-designed Axial Flux Permanent Magnet motor offers several benefits.

Low Profile

The general structure of the AFPM motor is mainly responsible for the low height of the ECORD.

Slotless

The printed circuit board (PCB) stator windings, with the rotor magnets on either side, allow for a slotless motor design, providing smooth motion.

Configurable Winding

The motor windings comprise several identical PCB stators that can be grouped and bonded in a specific manner to provide the desired winding configuration.

Direct Drive

No gear-reduction is used in the ECORD in order to reduce complexity and cost.

Electronics

Controller Board

The heart of the ECORD electronics for motor-control, user interactions, and safety systems.

Details
  • Main- and UI-microcontrollers, motor-controller IC
  • Motor-driver electronics, heatsinked to top plate
  • Three-phase output at 11.6A peak
  • Differential Hall (U, V, W) and encoder (A, B, I) input
  • Power-path circuitry for current-flow control
  • Bus voltage/current and temperature sensors, 3-axis accelerometer
  • Interfaces for RF-transceiver and Bluetooth module
  • Interfaces for display, audio amplifier, and pushbuttons
  • DC bus 60V nominal

Energy Dissipator Board

Energy put into the system during the concentric phase of an exercise is dissipated as heat to keep all electronics safe.

Details
  • Six 150W 50-Ohm resistors in parallel
  • Heatsinked to bottom plate
  • 3-phase motor interface for ease of wiring and installation

Encoder Board

Provides Hall and high-resolution encoder signals for proper motor commutation.

Details
  • Operates with magnetic wheel mounted on motor shaft
  • Encoder count and Back-EMF alignment set via programming port
  • External EEPROM stores programmed parameters
  • Single-ended to differential converters for Hall (U, V, W) and encoder (A, B, I) signals
  • Low-profile design: 5.9 mm total height including the magnetic encoder wheel.

Sensor Board

Part of the tension feedback mechanism. Calibration required to map sensor output to weight.

Details
  • Measures cantilevered beam inductance
  • Embedded printed coil
  • Programmable parameters
  • SPI interface

Future Developments

The ECORD operates as a standalone device without connecting to a smartphone or being remotely controlled, however, hooks are in place to support wireless connectivity.

Bluetooth Connectivity

Connect to a smartphone and evaluate exercise performance.

Wireless Transceiver

With a small remote control attached to the exercise handle of your choice, increment/decrement the weight mid-set. It’s like having a spotter, minus the bro science and protein shake recommendations.

ECORD App

The ECORD App will gather and analyze exercise data over time to help determine the effectiveness of the fitness program.

Gallery

Proof that even prototypes can get shredded.
Check out ECORD’s glow-up.

Concept motor assembly-mechanism showing bottom rotor.
Concept motor assembly-mechanism with top and bottom rotors.
Concept prototype of motor.
Concept motor with COTS encoder in test fixture.
Bottom plate with motor.
Bottom plate with motor and initial spooler design.
Initial design of tension feedback mechanism.
Working concept prototype.
Backiron of ECORD motor with half of the magnets bonded.
Completed backiron assembly.
Improved motor assembly system.
Fully assembled ECORD motor.
Spooler knot testing at 115 lb.
Motor with low-profile spooler and phase wires.
Partial assembly of bottom plate.
Sensor feedback calibration.
Internal assembly.
ECORD working prototype.
ECORD working prototype.
Power plugged and ready.
Power on!
Starting weight at 0 lb., ready for user input.
Set to 25 lb. and ready to begin.

“Patent pending. Arm pending—because it’s too massive to finish. If you’re interested in licensing, asking questions, or just trying to figure out how a motor made me this shredded, hit the contact form. I’ll make sure your message gets through. Assuming I can stop curling long enough to read it.”

Go back

Your message has been sent.