The Porticos engineering team focused on a self-centering knob mechanism that has the desired feel for an appliance user. For example, if you are turning on an appliance to a certain setting, intuitively, you would turn the knob to an appropriate angle or position on the dial or readout on a display. The knob then returns to the center or neutral position, and the user can shift the setting by a similar rotation in the opposite direction.
The self-centering mechanism about the knob’s center of rotation was the key design challenge. The knob was required to have the same feel for each direction of rotation and must “self-center” softly without noise, overshoot, or bounce about the center.
The user may also want to “feel” an increase in torque related to the angular position of the knob. The rocker design shown in this video demonstrates this successfully.
One of the designs allowed for changing the torque relationship with a cam-like surface on custom-profiled component parts. Several design options were presented to meet the knob requirements.
The Porticos team analyzed the torque profiles and built the rocker mechanism for testing in a prototype knob. Five units were built, and the machined plastics were treated with an SL Armor coating to simulate the brushed aluminum look.