Speed limiter - 24v Motors

Question

I'm looking for a way to limit the speed of some wheelchair motors in order to gain better control when using them in my RC device.

Currently the motors are very sharp and don't ramp up to speed, which makes it difficult to make delicate movements.

As such I thought that reducing the input voltage would help; but I wanted to do this in a way that I could adjust the amount of speed limiting. E.g. 12V slow speed - 24V max speed (and anywhere in between).

As such, I thought some sort of Voltage Regulator/Variable resistor would be appropriate, but I'm concerned when it comes to the Amperage value and need a bit of guidance - or to be honest - told if this is the correct way of thinking or not.

I've sort of drawn out a (very basic) sketch of the proposed wiring diagram for your consideration.

Any help with this would be much appreciated.

Thanks

---

[Update]

Thanks for all the replies - I thought it best to update the post.

The motor controller I'm using is from a Company called Cytron: Cytron 30A Bi-directional Dual Channel DC Motor Driver Controller. Link: enter link description here.

Whilst I do have full control over the speed of the device, it's the granularity and sharpness I'm looking to smooth out - as well as add a variable speed limiter that allows me to select a maximum speed so that if I were to loose concentration and pushed the joystick to top speed, it would max out at 3Mph for an indoor environment or full speed outside.

Answer 1

OK so if I understand correctly, you're trying to do 2 things:

1) Smooth the motor driver output so it's not jerky if you push your joystick to 100% fast

2) Add an extra feature where the max speed is different indoors and outdoors

1 can maybe be resolved by getting a different driver that does this smoothing, but it might be hard to find. 2 requires that you add custom hardware or a microcontroller. If you're not particularly comfortable designing electronics, the easiest way to go about this might be to add a microcontroller between the RC controller and the motor controller, and write code that implements the smoothing and the indoor/outdoor feature. You can connect the RC1 and RC2 signals to ADC pins, and control the motor controller via serial, PWM, or DACs (see manual). Connect whatever you're using to detect if you're indoor or outdoor to the microcontroller as well. Adafruit's Trinket Pro 5V would do if you use serial - https://www.adafruit.com/product/2000 . If you're comfortable with Arduino, this should be pretty straight forward. Good luck!

Answer 2

If you have the ability to use pulse-width modulation (PWM), that's generally the way to go in my opinion. Adding resistors will create a lot of heat and waste battery energy. You can create a smoother ramp-up via SW my ramping up the PWM duty cycle from 0% to 100% over a few seconds.

Answer 3

If I'm reading this correctly, you're already aware of H bridges and motor controllers and all that?

So then what you're looking for is some sort of low gear / high gear sort of deal to make the system more controllable in small spaces and still fast enough for outdoors?

Here's some options I would consider:

1. Get a better motor controller. There's no electrical reason that a controller can't go very slow with a full voltage. Combine that with a dual rate switch on the RC side.

2. Maybe that's not an option for some reason? In that case you could try to use a high power DC switching regulator. You could either try to control the regulator output, or just hook up some relays to use or bypass the regulator. The trouble will be finding a regulator that can supply enough power. These types available on amazon are fairly economical if your current is less than say.. 10A: DC Buck Converter, DROK DC-DC Step Down Voltage Regulator 10V-75V 60v 24v to 0-60V 12v 5v 12A DKP6012 Digital Control Volt Reducer Board Power Supply Module with LED Display & CC CV Mode