@Omer Very good question - climbing stairs raises some additional questions like traction / grip. You also need to determine how you want to climb the stairs: using traditional tracks or other more “creative” method.
It would be really nice if this calculator had a gear ratio input. What would be an easy way to offset the output for gearing? Could you just divide the actual wheel diameter by the gear ratio before entering it and end up with the same effective torque reduction?
@Nick Consider the output torque and RPM - if you want to find the motor’s specs without the gear ratio, divide the torque by the gear ratio, and multiply the RPM by the gear ratio. We did not include this because we strongly suggest using a gear motor system with motor already connected.
Starting torque of my dc motor is 4 Nm (without using gear). Will i increase starting torque using gear??
Hi, please what type of battery and motor would you suggest given the data from your calculator
Input
Total mass:25 Ibs
Number of drive motors:1 [#]
Radius of drive wheel:1.5 in
Robot Velocity:1 ft/s
Maximum incline:45 [deg]
Supply voltage:12 [V]
Desired acceleration: 0.254 m/s2
Desired operating time: 2 hours
Total efficiency: 65[%]
Output (for each drive motor)
Angular Velocity: 8.0000 rad/s
Torque*:4.7796 Nm
Total Power: 38.237 W
Maximum current: 3.1864 [A]
Battery Pack 6.3728 [Ah]
Thanks
@Chudi With only one drive motor, do you plan to use rack and pinion steering, or was that a mistake? Skid steer requires two drive motors. A 45 degree angle is really very steep, and the equations factor in acceleration up an incline, which may not be the case.
sir i’m working on my project which is solar powered vehicle the structure is around 400kg please tell me which motor is suitable
@coleman. Respected sir, I am going to design a mobile robot for some specific applications. The details are as follows:
- mass= 15 kg
- acceleration = 0.55 m/s^2
- number of drive motors=2
- radius of wheel= 6 inch
- velocity = 2.2 m/s
- incline = 15 deg
- supply voltage = 12V
- operating time = 2 hrs
i would be truly grateful if you could suggest me a dc geared motor which would suit my needs. I am also looking for an incremental encoder to go with that. Kindly help me please.
Thank you.
Nithin
@NITHIN MOORTHY We see you have also contacted us via the support center, so we will reply there.
Hi -
great calculator, thanks a lot for this! I am going to start a first DIY toy car project, and my input parameters seem to make sense to me (except I am not sure whether I want/need 6V or 9V or 12V, so let’s go with 9V for now):
Total mass: 1kg
Number of drive motors: 2
Radius of drive wheel: 0.05m
Robot Velocity: 5 m/s
Maximum incline: 30deg
Supply voltage: 6V
Desired acceleration: 5 m/s2
Desired operating time: 1h
Total efficiency: 65%
This gives me the following results, but I need help interpreting this:
Angular Velocity: 955.41 rev/min
Torque: 3.8834 kgf-cm
Total Power: 38.096 W
Maximum current: 4.2329 A
Battery Pack 8.4658 Ah
Ok, so what is not clear to me from above is what are the specs of the motors that I am looking for?
Does this straightforwardly translate into motors where the specs say (for each of the two) that at maximum efficiency I get
- torque of about 4kgf-cm / about 0.4Nm / about 55oz-in
- speed of about 1000rpm
- about 40W
- current of about 5A
??
Next question then of course: does such a thing exist? Unfortunately, it doesn’t seem to be possible to filter your DC Brushed Motors by these specs, so it’s quite hard to go from the results to the calculator to a choice of motors (and then from there to a choice of matching motor controllers). Plus of course it gets more complicated with the option of throwing a gearbox into the mix…
For example, with above “specs”, how about the https://www.robotshop.com/en/rs-775-motor-7000rpm-12v-7613oz-in.html which gives me (At Maximum Eff):
Speed: 6070 rpm
Current: 5.25 A
Torque: 725g-cm
Output: 45.19W
Efficiency: 71.8%
So if I add a 1:6 gearbox to this(???), I should roughly get
Speed: 1010rpm
Torque 4350g-cm
Which is pretty close to what I need, with some headroom to go?
PS: Yes, I realize that 1kg is maybe a bit heavy for my velocity and acceleration “requirements”, but first of all I want to make sure I understand how to go from the calculation results to specs that I can use to narrow down my choices of motors (and then motor controllers). I can then still lower the weight of the vehicle and/or my velocity and acceleration requirements.
Thanks in advance and sorry for the long question…
@spinetrak Given the length of the post, can you create a new topic on the RobotShop Forum here: https://www.robotshop.com/forum/motors-actuators-controllers-f78 Once there is a new topic, we’ll shorten the reply here and reply there.
Hello… I have to build a robot car with max velocity of 0.4m/sec and total load of 10kg. it will be used mainly for constant velocity buyt we need to control the speed with an external ESC (speed controller) if needed (from 0 to 100% speed (100% = 0.4m/sec)). I understand all the parameters except the " desired acceleration". I don’t know what to put there. I saw that it affects seriusly the torque of the moter. It will be used to cary video camera and cinema loads (cameras etc).
@George To calculate the acceleration, consider the total time you want the robot to travel before it reaches the desired speed (v1 = v0 + a*t). In the forumula used here, it is a bit more “worst case” scenario because the robot is placed at your specified incline.
Thank so much for the fast response. It seems that I will need a motor of about 150-160 rpm and 7 kg*cm torque, and about 1A current. I think a battery of 9v or 12v is perfect for my project. I m thinking to use 1 brushless motor (becouse I need very low noise) instead of a brushed motor. I also need to control the speed from around 0% to 100% (100% = 0.4 m/sec, and 0% = 0 m/sec). Please can you suggest me a motor and an electronic speed controller ?
@George RobotShop’s current selection of brushless geared motors is unfortunately limited, and we do not have any products to propose which would meet the specs.
Hi. Nice calculator. I’ve calculated 2 kgf cm torque. What “torque” should I look for if I will be using stepper motors?
I see that it is common in steppers the “holding torque”, how much of it should I look for?
Thanks!!
Hello… this is a great tool. However, the output speed of a motor is with NO load or WITH load (load equal to mass) ? For example if I have a load of 3kg and need a speed of 0.5 m/sec on 0.03m wheel (car wheel) program says that we need a motor of 160 rpm. 160 rpm refers to NO load speed of a motor ? or we have to search of a motor of 200 rpm (no load) since if we put load on motor the (no load) speed decrease ?
@ReyC Normally stepper motors are not used for propulsion systems in mobile robots. The torque of a stepper motor when in motion is quite different (lower) than the holding torque.