I am trying to design a magician’s top hat, which can expand from a collapsed state, using remote control. Attached is an image, showing the general concept. I will mention that collapsing top hats are known a “Opera hats” because they were popularized when top hats were common formal wear, and users could collapse them to store under their seat.
These types of hat have a rigid brim, and top disc. Then, there is fabric that connect the two. The traditional design has 4 spring-loaded linkages around the perimeter. This is what I want to motorize.
In my picture, the linkages on the servo is 2 3/8" long (center to center). But, I can’t find one this long. Also, I am a little concerned that such a long lever arm is side loading the servo in a way it is not designed to be used. The robot joint systems handle this by attaching a |_| shaped bracket that provides a pivot point on the back of the servo. These won’t work for me, because the way they are designed takes up far too much space. And I need the pivot point to be as close to the permimeter of the hat as possible.
Also, I would love to get a connection to the servo that is not a spline. I am surprised the robotics world has not generated servos that have output shafts with flats on them, or that have shafts going through the entire servo so they can handle a cantilevered load when used with wheels.
I know I can purchase small gear motors with encoders, that have the mechanical features I would like. But, then it gets more complicated to design the control system and the control board starts to get larger, etc. I considered using dumb gear motors and send them to their extremes of travel, where they stall. But, because I need enough speed to open the hat fast, they need to be fairly powerful, and I am concerned they would damage things.
So, I am hoping someone can suggest one of the following,
- A servo that has a mechanical connection that is not a spline.
- A source for servo horns (that use the typical spline to connect) with at least 2 3/8" between the holes.
Thank you for any replies.