Bambu Lab just released info on the H2C, a 7-color hotend-switching multimaterial printer. Retrofits from H2S,D to C will be available, continuing the Bambu Lab tradition of parts sharing (so this system was likely codesigned with the H2D).
In order to prevent mechanical contact wearout during frequent switching (also very relevant for robotics!), the hotend is fully wireless:
It uses induction heating for the hotend in 8 seconds; the X1 series takes about ~30s-1m to heat up, so this is at least a 3x increase in power (assuming similar thermal mass, which the new one has much more of due to the thick iron jacket around the hotend used for heating. I'd estimate about 250 W of heating power is available. This was likely unachievable in the past because of the thermal resistance between heater and heatblock before.
The coil is likely driven using a low voltage, likely resonant driver (but due to low voltage, hard switching has a much lower loss, so the heater will be able to operate out of resonance in order to avoid a dead band near 0 power and smooth heating control.
The sensing is done through two small antenna coils to transmit power and data over small range inductive.
A major challenge in creating this system is that the coil needs to operate in a very difficult EMC environment due to proximity to induction heating coil. A small amount of power is transmitted and rectified on the PCB to power the MCU, ADC and AFE for the temperature sensor/ID, and the data is sent back over RF.
The size/scale of Bambu Lab allows them to absorb the cost of what looks like a custom radio protocol associated intentional radiator certification. It is likely that they are using a custom SubGHz protocol which chips are not readily available for. I believe that in the future, applications such as humanoid robot joints, etc will create very high volume demand for these robust, high data rate short range inductive/RF wireless communication bridges, and I can imagine an ecosystem exists for some fabless IC vendors to deliver standard solutions for this.
The hotend switch system is pretty well designed and makes the best use of mechanical hardware. Two sets of three hotends alternately raise and lower (thus using only one motor and belt), and the hotends are grouped into sets of 2 for toolhead clearance.
I'm guessing (unclear from video) they are using a nested stub inside the fitting to locate/align/secure the hotends with a hidden mechanism to lock the hotends onto the toolhead. Note that the toolhead has one fixed hotend and one swappable hotend, and thus it's likely that all upgrade paths from H2S will end up as a dual.
Hotend cradles look passive to me, maybe using magnets to hold them onto the holders (with some thermal insulation pads inbetween?)
It is clear that the DJI heritage lives on in Bambu, with a deep set of expertise in power electronics, RF, motor drive, office automation mechatronics design, and consumer electronics productization.