Drivers like to perceive a linear relationship between pedal effort and stopping: the harder you push the faster you stop, and the farther the pedal travels the faster you stop, with little pedal travel before the deceleration starts. In EVs it’s preferred that all of the braking comes from regenerative braking, that is, only from the motor charging the battery. On high speed stops, that’s not possible, so the braking algorithm must add in friction braking during the stop. When the control algorithm starts to add in friction braking it is important that the driver has minimal noticeable change in pedal travel or force.
Unfortunately, duo-servo drum brakes (shown in the very poor artists drawing in the article), are notoriously non-linear and variable in output, regardless of how ingenious the software is. this makes the add-in point move around due to humidity, temperature, cooling since the last stop, days since last rainfall, etc. Disc brakes are simply less variable than drum brakes, regardless of how frequently they are used.
The issue I was making with temperature had to do with cooling, not thermal capacity. The brake drum simply blocks much of the cooling air flow. that’s why you see disc brakes on the front of virtually every car sold in the USA. The fronts are where most of the braking energy is absorbed, because of weight transfer to the front axle during stopping. Regardless of lining surface area, it’s the metal parts that absorb most of the energy on drum and disc brakes. Drum brakes simply don’t cool as fast as disc brakes, particularly when there’s a motor inside of them blocking the air, and also adding heat.
“Disc brakes are simply less variable than drum brakes, regardless of how frequently they are used.”
Heat is not a concern in a panic stop. However disk brakes degraded due to lack of use is.