I need to determine the best method for holding open the pages of a book in my robotic page turner. I was going to use two motors with some sort of an arm to hold open both sides of the book. I am thinking if I apply the necessary force to hold open the pages, the motors will be generating stall level current, which will probably waste a lot of power. I would prefer to have my motors rest while they wait until the next page needs to be turned. What would be a better way of holding it open?
necessary torque for holding open a book
Jul 17, 2007
7 Replies
One way would be to make a retractable detent acting perpendicularly to the direction of force. Retract the detent while turning the page, then extend the detent to hold the book open after the page is turned. Kinda like a crossbow works. It takes alot of force to pull back the string and hold it, but once the trigger mechanism (the detent) catches it, it doesn't require any force to hold it back.
BRW
There's nothing wrong with running a motor into stall, if you have the feedback to do it properly. It's a standard force control problem. If you want to hold something in place with a small force, you can program a motor controller to do that. This is much easier to do electrically than mechanically.
John Nagle
BRW wrote:
Those are some helpful suggestions. I thought of another idea that perhaps might work as well. I was wondering if I attached a small weighted ball to the arm/horn of a servo would that weight cause the arm to fall against the page and hold it down when power is switched off? I have never used a servo motor before, and it seems like I read somewhere that a servo has to be in a certain position to be at a state of rest. Is that correct? Would it be a better idea to use a DC motor for that purpose?
Those are some helpful suggestions. I thought of another idea that perhaps might work as well. I was wondering if I attached a small weighted ball to the arm/horn of a servo would that weight cause the arm to fall against the page and hold it down when power is switched off? I have never used a servo motor before, and it seems like I read somewhere that a servo has to be in a certain position to be at a state of rest. Is that correct? Would it be a better idea to use a DC motor for that purpose?
Those are some helpful suggestions. I thought of another idea that perhaps might work as well. I was wondering if I attached a small weighted ball to the arm/horn of a servo would that weight cause the arm to fall against the page and hold it down when power is switched off? I have never used a servo motor before, and it seems like I read somewhere that a servo has to be in a certain position to be at a state of rest. Is that correct? Would it be a better idea to use a DC motor for that purpose?
Those are some helpful suggestions. I thought of another idea that perhaps might work as well. I was wondering if I attached a small weighted ball to the arm/horn of a servo would that weight cause the arm to fall against the page and hold it down when power is switched off? I have never used a servo motor before, and it seems like I read somewhere that a servo has to be in a certain position to be at a state of rest. Is that correct? Would it be a better idea to use a DC motor for that purpose?
Sorry for all these extra messages. They wouldn't appear for a long time after I posted them.
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