CONCEPTUAL DESIGN AND FIRST PROTOTYPE
Our conceptual design and first prototype is a proof of concept. This will allow us mainly to develop the software, gain more understanding of the kinematics of the system and an insight how hard it is for a layman to install the product on a door. We will look for weak points of the mechanics, electronics and software and once they are identified, in another iteration, we will address them by redesigning it for the finalised commercially competitive version.
LINEAR MOTOR USED IN CONCEPTUAL DESIGN (Commercially available linear actuator):
Permanent Magnet DC Motor Drive Voltage: 12V DC
Maximum Thrust / Pull: 750N
Standard Stroke: S = 100mm
Standard Protection Level: IP54
Speed: 12 mm/s
We certainly see obstacles in the mechanical design and in the prototyping of both the conceptual design and the final one. Plastic parts will be SLA 3D printed and therefore the design should be optimized for both manufacturing and for operational loads when components will be in use. For metal parts we plan to use bought-in standard parts.
FINAL DESIGN WITH MASS PRODUCTION COMPONENTS
Our first prototype is meant to be only a proof of concept. The opening time is approx. 10 sec with the commercially available linear actuator, which makes the operation time too long. The reason for that is these linear actuators are designed for slow motion, short stroke but heavy load lifting. To be competitive with our product on the market, we plan to customize the linear mechanism to our application. In order to that the linear actuator will be redesigned with a helical screw-jack mechanism. It would give a much longer stroke for the actuator to enable to place the product further away from the rotational point (door hinges). It would give more leverage and more power for the product and also more space, because doors sometimes can be in corners of a rooms which limits space for the SmartDoor unit if it is too close to the door hinge.
The lead-screw nut of the screw-jack would be a maintenance free, self-lubricating, low-friction engineering plastic nut. A gear-set would be designed between the nut and the motor to reduce the speed of the motor and gain more power for twisting the nut. Due to the rotation of the nut in a housing supported by bearings, the non-rotating lead-screw will move linearly. The gear-set will be designed from high performance engineering plastic in order to be injection mouldable and all the covers around the product also from plastic, optimized for injection moulding serial production.
We also plan to design an extra coupling system into the product which can disengage the motor from the gear-set. The benefit of that would be to be able to open the door manually any time it is needed. Additional settings could also be instantly applied through the voice recognition system and tell the software if the door should be manually openable at the moment when instructed so or it should hold on mechanically and it only opens when the software is instructed to...
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