As new to Arduino and with no electronics background I would like to ask a few questions and if someone could help I would appreciate that.
1)could you suggest appropriate stepper motors for building a conveyor belt about 60cm length and 20cm width, and power enough for load 3kg-4kg (max) distributed equally in all 60cm. One way move, slow motion (i.e. 2cm /sec).
2)can I have 5 or more belts with an arduino mega without the use of a driver? Maybe a simple connection with pins? I don't want to use them simultaneously. One at a time for different use.
3) Could I use external power such as a 12V adaptor, or I need 24V power supply for this project?
4) Maybe (optional) function in case of motor failure give feedback.
5) Are there ready conveyor belts at 20cm width that will fit directly to my project or I have to make one on my own?
Note: I have experimented only with a servo micro in a previous project. I don't know if there are any common applications.
Any advice would be appreciated.
Thanks in advance.
Hi charavge,
You will have to look at many stepper motors to discover what size and power you need for that load. All steppers need a driver, they will not work directly from the Arduino and trying could damage the arduino. In fact besides an LED or 2! you should'ent power Relays, motors of any kind or servoes from the arduino power, they will take all the power or introduce noise both of which will cause the arduino to reset, and reset and reset.....
Yes you will need to use a good power supply and some steppers can demand a few Amps! there are lots of programs to run steppers, depends what you need it to do, some stepper driver boards just need an input for DIRection and a LOW to HIGH on the Step input, this I think would be the easiest way for you.
I have only played with simple steppers, but hope to run a robot on them one day!
There's lots of stuff out there just search! Google, etc.
I have been searching a few days before posting, but since I don't have a background I can't understand maybe simple terms for others like "Unipolar" vs "Bipolar" (even seen videos). So I can't decide which one is suitable for my project. Also what do I have to look into a stepper motor in order to achieve the load of 3kg-4kg working without trouble at a movement of 2cm/sec?
Maybe someone has already used a similar motor so I won't need to spend a lot of money just to find which one is the appropriate and that is the reason I am asking your advice here.
I won't use arduino's power directly, so far I have used a 12V adaptor with servos.
So far I understand I have to use a driver and external power.
Now the questions are:
how can I find the appropriate motor? I saw NEMA 17 and NEMA 23, but I don't know if one of them is appropriate. I read that a NEMA 17 from another NEMA 17 may be totally different.
Do stepper motors have a function in case of motor failure (motor won't work at all or won't complete the turns) to give feedback?
Are there ready conveyor belts at 20cm width that will fit directly to my project? Where can I find them?
The use of steppers suggests that you require a precise position to be attained. Your posts do not suggest that; they only mention speed and load. If that is all you require then steppers are an expensive and unnecessary method to go about it. If you do not need precise position control the use of geared dc motors and encoders would be sufficient and certainly less than half the price of what steppers and associated electronics and hardware would be. - Scotty
Thank you Scotty for your suggestion.
I need stepper because at spesific distance it must stop, wait and start again.
Tried to avoid stepper motors because it is more complex and cost more but the "specific distance" causes the need of this. Thanks though for the alternative.
Just saw this site: Stepper Motors | NEMA Stepper Motors & Controllers | Circuit Specialists
In the Specifications area I see that it says "Holding Torque(Kg.cm): 0.55". It means that it can handle 5.5 KG of load in 10cm?
Also there is no specification of the speed. Should I assume that the speed is controled from the driver?
In higher power ranges bipolar motors are the typical solution.
charavge:
how can I find the appropriate motor? I saw NEMA 17 and NEMA 23, but I don't know if one of them is appropriate. I read that a NEMA 17 from another NEMA 17 may be totally different.
Do stepper motors have a function in case of motor failure (motor won't work at all or won't complete the turns) to give feedback?
Are there ready conveyor belts at 20cm width that will fit directly to my project? Where can I find them?
NEMA 17 vs 23 vs 43 (etc.) just refers to the size of the mounting face of the motor.
Stepper motors do not provide any feedback by default. Only a motor with an encoder can provide that. You can add an encoder to a stepper but usually steppers of an adequate size are chosen so that missing steps is unlikely.
For a conveyor belt you should look at "tabletop chain". As the name implies its a wide, linked chain and not a belt but it's usually the practical solution. If you need rubber belt try looking at hay baler belt.
charavge:
Just saw this site: Stepper Motors | NEMA Stepper Motors & Controllers | Circuit Specialists
In the Specifications area I see that it says "Holding Torque(Kg.cm): 0.55". It means that it can handle 5.5 KG of load in 10cm?
Also there is no specification of the speed. Should I assume that the speed is controled from the driver?
It holds .55kg at a 1 cm distance from the center of rotation (the shaft). It holds .055kg at 10 cm.
Speed is controlled by you. 2000 RPM is a typical maximum, and beware that torque decreases with increased speed.
Beware that dynamic torques with a stepper are much less than the static holding
torque (and cannot be calculated really - they depend on resonance and the ramping
rate of steps).
There are two ways to do the precise stopping you require, open-loop with a stepper
or closed loop with a sensor. With closed loop you can use cheaper motors and
drivers, but you'll need some sort of position sensor (which note that you will perhaps
need anyway to setup a stepper motor system at power up into a known position).
Stepper motors are far less power efficient too, so unless you have a requirement to
stop in many different positions accurately, they are likely not the ideal option.
Chagrin:
In higher power ranges bipolar motors are the typical solution.
NEMA 17 vs 23 vs 43 (etc.) just refers to the size of the mounting face of the motor.
Stepper motors do not provide any feedback by default. Only a motor with an encoder can provide that. You can add an encoder to a stepper but usually steppers of an adequate size are chosen so that missing steps is unlikely.
For a conveyor belt you should look at "tabletop chain". As the name implies its a wide, linked chain and not a belt but it's usually the practical solution. If you need rubber belt try looking at hay baler belt.
It holds .55kg at a 1 cm distance from the center of rotation (the shaft). It holds .055kg at 10 cm.
Speed is controlled by you. 2000 RPM is a typical maximum, and beware that torque decreases with increased speed.
Chagrin thanks for your complete answer.
How can I calculate the torque / distance? I made a draw in order to help you understand what I need.
MarkT:
There are two ways to do the precise stopping you require, open-loop with a stepper
or closed loop with a sensor. With closed loop you can use cheaper motors and
drivers, but you'll need some sort of position sensor (which note that you will perhaps
need anyway to setup a stepper motor system at power up into a known position).
Stepper motors are far less power efficient too, so unless you have a requirement to
stop in many different positions accurately, they are likely not the ideal option.
Thanks Mark. That would be ideal. What if sensor fails? Also, how can you control speed? Some DC motors I checked are a bit less expensive from a stepper motor.
charavge:
What if sensor fails? Also, how can you control speed?
A sensor is no more likely to fail than any other part of the apparatus.
You have not told us enough about what your project is intended to do.
What determines the point(s) at which it must stop ?
How precise must the positioning be - +/- X mm ?
What speed does the conveyor need to operate at - metres per second ?
Why does it need variable speed ?
Over what range does the speed need to be variable ?
A large part of the force needed to drive the belt will be determined by friction between the belt and the surface it sits on. I suspect the only way to determine that is by experiment.
The torque for this kind of set up is dominated by friction so you can't calculate it really.
Build the mechanism or a part of it and measure the torque needed before committing to
a final decision. You could assume a coefficient of friction of about 1.0 as a conservative
estimate to get very rough ballpark figures. Belt tension markedly affects friction.
With steppers you have the added problem that the dynamic torque is a complex function of
damping, speed, acceleration, driver and so forth, so you need to look at the torque v. speed curves
for motors and choose one that is generously specified, or else expect to have to tune the
maximum speed and acceleration on the actual machine - it might perform somewhat
differently from expectations.
Robin2:
You have not told us enough about what your project is intended to do.
What determines the point(s) at which it must stop ?
How precise must the positioning be - +/- X mm ?
What speed does the conveyor need to operate at - metres per second ?
Why does it need variable speed ?
Over what range does the speed need to be variable ?
A large part of the force needed to drive the belt will be determined by friction between the belt and the surface it sits on. I suspect the only way to determine that is by experiment.
...R
The belt is intended to move several kinds of objects with max. weight 1KG each.
There will be 4 positions of 1 Kg load each (total 4KG). Each position is 15cm on the belt (60cm length and 20cm width). Imagine transfering bricks. So must stop every 15cm. Maybe later the positioning will change and become 7.5 cm and 0.5Kg. I don't care if there are some mm - + but 1 cm is problem (this is what I have in mind).
The speed I need is not variable. It is calculated at 2cm / s (I need slow motion).
I have seen some projects and I will test a couple of things for the surface friction.
Maybe I start trying some things and I will make it more specific later.
PS: Robin the tutorial about motors was very helpful to understand some things.
charavge:
Maybe I start trying some things and I will make it more specific later.
That is a good idea.
From your diagram I get the idea that you could identify the position by using a light beam that is broken by the blocks on the conveyor. That would automatically adjust for different sized blocks and for the possibility that some blocks may be further than expected from the preceding block.
With a slow conveyor I imagine that a geared DC motor would be the best option along with some system to detect position.