Help on selecting a proper motor and drive

Hi, I am new to this business, so please accept my stupid and basic questions. I am working on a project which requires a motor can do a specific job and I am not sure which motor to order. and to avoid ordering wrong parts, I need your advice. The required motor should do the following:

1- I have a load 4-5kg and the motor should push / pull this load in two directions (on a long bar) to a specific distance (3ft) only, then should stop by itself on a specific point fixed by me as a safety point. (the bar is much longer than 3ft).
2- The motor should be programmed to move maximum 3ft on the left and 3ft on the right (total 6ft left/right)
3- I should be able to stop the motor the point and the time a like within this 6ft.
4- The motor should be smooth and accurate.

Now I am not sure which motor can do this job, is it a stepper motor? Or motor with encoder? Or other option?

Your feedback is highly appreciated.


I apologize for the delayed reply. I suspect no one has responded yet because your question is quite broad and you don’t really provide enough information for us to give you an answer. In order to select a motor, you have to have at least a rough idea of how much torque and speed you require. You might find this blog post about force and torque helpful.

Once you know what kind of torque and speed you are looking for, you can use our motor comparison table to see if there is anything we offer that meets your criteria. Note that the specs in that table are all at 6 V, but motors can typically be operated over a range of voltages, and free-run speed, stall torque, and stall current will all vary linearly with voltage. Also, some of the motors on that list are intended for operation at 12 V, so you will need to double the appropriate specs to see how they will behave at that higher voltage. Once you pick a motor, you can then select an appropriate motor controller (e.g. one that can deliver the necessary power and has your desired features).

I suggest you look for a DC motor with a quadrature encoder if position feedback is really important to you, though a stepper motor might work for you as well. However, if the motor stopping points are always at the same location, perhaps you could use fixed limit switches or some other motor-independent feedback to stop the motor at these points and skip the encoder feedback?

- Ben

Thanks B :smiley: en for your support. I believe the Metal Gearmotor model 1107 with 250 oz-in Stall torque @ 12V will do the job. I will order several of this motor for my experiments but I need your recommendation about the motor controller with built in speed control as I need the motor to run on a fixed speed. Regarding the control system, I need to control the motor in two ways, first one by RC Remote control or by using my iPhone. Therefore I have from Robot Market Place a Spektrum AR500 5Ch receiver and remote control and Wifi receiver, now my question is, do you think these two remote control module will be compatible with this motor? If not, can you suggest an alternative?

Quick note, I will use two motors at the time, one for H Movement and second one for V movement, so the motor controller required should be minimum with two channels. Regarding the stopping point, it’s not so important as I can forget about it.


I don’t understand what you mean by this. The general point of a motor controller to control the voltage to a motor (which in turn lets you control the speed). Your use of statements like “built in speed control” and “run on a fixed speed” make it sound like you’re looking for something more, such as a controller that supports closed-loop speed control. Is this the case?

This question doesn’t make sense. It’s like asking if your TV is compatible with a particular DVD. The key to compatibility is finding an intermediate device that can take the DVD as input and send the appropriate output to your TV. Similarly, you need to find an appropriate motor controller that can respond to your desired inputs and translate that into the proper outputs for your motor. The question you should be asking is what motor controller will work best with that motor and those control sources, not whether the motor is compatible with the control sources. I suggest you consider our Simple Motor Controllers. The user’s guide, available under the resources tab of the product page, should give you some understanding of what the controllers can do and how they might help you build your system. The Simple Motor Controllers can be paired or serially chained to give you control of multiple motors and can be controlled directly from an RC receiver. If your wifi receiver outputs TTL serial, you can connect that directly to the controller as well; otherwise, you will need some intermediate device between the wifi receiver and the motor controller.

- Ben

Sorry Ben,
Since the English is not my native language, so I might miss using the right words or a right description. For sure what in my mind is something deferent than what I wrote to you.
I will simplify my question as follows:

1- Built-in speed control: I need the motor to push / Pull the load on a fixed speed. For example 1 inch/second all the way same speed. And I mean by built-in speed control is having a potentiometer on the motor drive module to fine tuning this speed. This is not a must but if it’s there, it would be great.
2- Regarding my second question (do you think these two remote control module will be compatible with this motor?), I am sure this is the most stupid question you ever received. Any way what I need is two separate motors from same model, first one to be controlled via RC (Remote control) and second one with Wifi (iphone). There will be no relation between both motors, both will work independently.
3- Regarding stop points, I may use switches to stop the motor on a specific point. But also this requests not important.
Hope this time my discretion will make sense,

I am not familiar with any product that lets you activate a motor with an RC/Wifi signal while controlling the speed with an analog voltage. Our Simple Motor Controllers let you control the speed with RC signals or TTL serial commands (which you could conceivably generate from some kind of Wifi-to-serial device). If you really want the potentiometer in the mix, you will need a custom solution, though you might be able to do it with off-the-shelf parts. For example, you can use our Simple Motor Controller in analog mode connected to a pot that controls the speed and then use an RC switch to selectively trigger a controller error condition (and stop the motor) with RC. For your Wifi-controlled motor, you could use our Simple Motor Controller in serial mode with a pot connected to the analog inputs. You can then serially request the pot value from the SMC and send the appropriate motor speed commands based on that value.

I’ve received far worse questions! If your motors are completely independent and you need them to be controlled by different interfaces, it doesn’t make sense to look for a dual motor controller. I suggest you look for two single-channel controllers, one for each motor. They don’t have to be the same model controller, either.

- Ben