BelayOn is a semi-autonomous lead-belay system, enabling rock climbers to lead-climb without a partner for the first time.

BelayOn was my senior capstone project, showcasing expertise in:

  1. Needfinding

  2. Design/Build

  3. Test


There are two methods of belaying a rock climber: Top Rope, and Lead Belay. Currently, only top rope climbing can be done without a partner. Before BelayOn, lead climbers had no way of practicing without coordinating a partner.

We created BelayOn to be the first-of-its-kind solution to lead climbers lacking a partner.


Since designing, machining, and assembling this product would take months, I modeled the dynamics of the system and validated the model with a small scale test. This allowed me to make design decisions on the fly before committing to an expensive, robust final build. I built the model in MATLAB, and the brake dynamics, as well as real world application, are shown below.

We used a magnetic break because it could:

  1. Operate independently of power loss

  2. Withstand multiple independent failures without injuring a climber.

    1. Three independent brakeplates running through a magnetic field safely belay the climber. However, the system is still capable of safely belaying individuals down at safe speeds if two brakeplates fail.
  3. Provide enough "give" to not hurt a falling climber with too fast a deceleration.

  4. Work for climbers between 50-200 lbs.

  5. Limit wear, tear, and performance degradation.

    1. Because the magnetic break has no friction force, the only wear is on the linear sliders and the axle bearing.
BelayOn Model no climber.mp4

The Final Model is shown above.

  • At low speeds, the magnetic break produces effectively no braking torque.

  • At targeted steady state descent speeds, a very small change in speed leads to a significant increase in torque.

    • This means a 100 pound climber and a 200 lb climber will descend at almost the same speed.

BelayOn! Model.mp4

The video above shows 4 steps.

  1. The climber ascends at a very slow speed, leading to a negligible torque that can be compensated by a small motor. This motor prevents the climber from having to deal with a further resistive force.

  2. The climber falls, and at freefall there is no rotation in the magnetic break.

  3. The rope goes taught, and the climber experiences a maximum deceleration force.

  4. The climber slows to a stop and can continue to climb back up or belay back down.


After some serious time in the machine shop, we had a final assembly! We tested with weights from 15-170 lbs. Note how during freefall, the brake does not move. Then it catches the falling mass and and slows it before a safe reconnect with the ground.

My Role

I was the lead designer for the eddy current brake. I created the model we used for design, and worked on a team of 3 to CAD, machine, and assemble the descent subsytems.

Ascent Subsystems

The other half of the team created the ascent subsystems, a motor that monitored and provided slack so that climbers could climb without extra downward force being exerted to simulate an active human belayer.

Notice how as the climber pulls, the control system monitors rope slack to ensure that the climber never has to fight the brake or the motor!