So I’m lifting 150lbs approx (200 to be safe) on 4 posts. It has to lift about 5.5 feet in less then 1 minute.
I’m considering 4 of the following motors. Will this work?
What controllers will I need?
What power supply will I need for the 4 motors?
robotshop.com/en/neverest-40 … swodg-gOIw
thanks
Rob
It sounds like you’d like to create your own custom linear actuator? If so, you’ll need a lead screw as well. You need 1.1 inches per second under load, which is around 40 pounds.
Note that the gear motor you selected has an encoder (which you don’t necessarily need to use unless you want to ensure they all operate at the same speed).
If you want simple on/off/reverse you don’t need a motor controller - a DPDT switch which can handle the current is enough.
Ex: robotshop.com/en/dpdt-20a-toggle-switch.html
If you want to use the encoders, you’ll need a microcontroller and either 4x single DC motor controllers, 2x dual DC motor controllers or 1x Quad motor controller (for independent control of each motor).
The motor consumes around 2.5A under load, so you need a 12V, 10A+ wall adapter.
Your first issue however is creating linear motion out of the rotational motion of the gear motor.
I was thinking about a chain drive…the screws can get really expensive.
Top cog…bottom cog…or a winch…bottom motor with cable over a pulley in the top of the post…all options.
Any way we could connect by phone…lots of questions …
The bed would lift, but what would keep it in place? Do you know how to convert from torque (rotational actuator) to linear force?
Phone control is certainly possible, but you’ll need a microcontroller, Bluetooth module, motor controllers and a compatible App.
How comfortable are you in robotics / electronics / programming?
Hello there. I thought that gear motors would hold in place “standing torque”…
I’ve been reading about motors and have converted the oz-in to lb-in…which means the linear force with a radius of one inch from the shaft if I’ve been reading correctly.
I do programming iOS and dabble with my rasberry PI and python …so I have that end of things kinda covered. I’m looking to find the hardware solution that fits my needs.
Thanks for all the help so far…
A DC gear motor really only has two settings: not powered or powered. If a moor is powered, it will rotate. If it cannot rotate (either the load is too high or there is something preventing it) it will stall and burn. Internal friction is not enough to keep it from rotating, though for higher gear ratios, the torque needed to back drive it is higher than non-geared. Under the load you indicated, the motors would likely just spin freely causing the bed to drop back down.
Torque is essentially force multiplied by distance (should not be simplified this much). Therefore with a radius of 2 inches (4in diameter) and a torque of 31 foot pounds of torque, the force at the radius would be 31/2 = 15.5 pounds.
The motor you linked to can provide 350oz-in of stall, or 1/4 that continuously (never operate even close to stall). Therefore the max continuous torque would be 0.4 pound feet. To lift 50 pounds, you would need a wheel of 0.008 foot radius (not possible, therefore that motor is severely underpowered). You need something like:
robotshop.com/en/12v-5310-rp … motor.html
robotshop.com/en/banebots-p8 … 12to1.html
Together these can produce 1030 oz-in (5.36 pound feet) at ~442 rpm (no load). You would need a pulley of radius 0.1 feet (1.3 inches).
