Should I use a potentiometer or Quadrotor encoder?

In summary, the HEDS-9040/9140 series has a rotary encoder with an optical code disk that can be mounted directly on a shaft. It has two channels that provide quadrature data, and one channel that provides one index pulse per revolution. It is less expensive than other options and has fewer frictions.
  • #1
Jarfi
384
12
Specifications:
Measuring angle from -90 to + 90 degs.
Low friction
Low moment of inertia
Requires high speed
Accuracy about 1° degree.
Needs to be durable, handle mechanical vibration

I use a dc motor as an actuator, this is a custom built servo. This is a very small device, and the encoder must be low in weight, just several grams

Main problems:
Potentiometer: Noise, high friction
Simple ADC reading, no programming required nor are there any interrupts

Quadrotor encoder:
High CPR encoders are typically made for large motors, too big and clunky. They are also more complicated as they include interrupts
No friction, no noise

What should I generally go for, what are people using in servomotors for small but accurate robotics

I'm having trouble finding either, that fit the space requirements and accuracy requirements(at least 360 CPR)
 
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  • #2
Avoid a resistive pot if possible. Do you need to know where zero is ?
A rotary encoder with an optical disk will probably be your best minature low mass integral solution.
An example would be the AVAGO; HEDS-9040#J00 with an optical code disk.
http://www.mouser.com/ds/2/678/V02-1132EN_DS_HEDS-9x40_2014-03-170-1130980.pdf

Start here to see an example of possibilities: https://au.rs-online.com/web/p/rotary-encoders/7967874/
Essential accessories show optical code disks, with through holes, that will mount directly on a shaft.

https://www.ebay.com.au/itm/HEDS-9040-J00-Optical-Incremental-Encoder-30000rpm-Digital-2000-Count-Multi-Qty/302531789915?hash=item46704cc45b:m:mDIJZ1jmIVQhLHIYKJaX6ww
 
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  • #3
Baluncore said:
Avoid a resistive pot if possible. Do you need to know where zero is ?
A rotary encoder with an optical disk will probably be your best minature low mass integral solution.
An example would be the AVAGO; HEDS-9040#J00 with an optical code disk.
http://www.mouser.com/ds/2/678/V02-1132EN_DS_HEDS-9x40_2014-03-170-1130980.pdf

Start here to see an example of possibilities: https://au.rs-online.com/web/p/rotary-encoders/7967874/
Essential accessories show optical code disks, with through holes, that will mount directly on a shaft.

https://www.ebay.com.au/itm/HEDS-9040-J00-Optical-Incremental-Encoder-30000rpm-Digital-2000-Count-Multi-Qty/302531789915?hash=item46704cc45b:m:mDIJZ1jmIVQhLHIYKJaX6ww
Thanks.

I've been weary of resistive pots, its simply that they are ubiquitous.

I do need a zero location, however I use a simple calibration on startup methods, where the motor drives the mechanism to a certain start point, all the way to the end, where a switch might be located. So an absolute sensor is not required. Dead reckoning is enough.
 
  • #4
Jarfi said:
I do need a zero location, however I use a simple calibration on startup methods, where the motor drives the mechanism to a certain start point, all the way to the end, where a switch might be located.
You do not need the switch with the HEDS-9040/9140 series, since it has three channels, two are phases in quadrature, the other gives one index pulse per revolution.
 

1. What is the difference between a potentiometer and a quadrotor encoder?

A potentiometer is a variable resistor that measures the change in voltage as a rotational movement is applied. A quadrotor encoder, on the other hand, is an electromechanical device that measures the rotation of a shaft in degrees or revolutions, providing precise position feedback.

2. Which one is more accurate, a potentiometer or a quadrotor encoder?

A quadrotor encoder is generally more accurate than a potentiometer. This is because a potentiometer is susceptible to wear and tear, temperature changes, and electrical noise, which can affect its accuracy. A quadrotor encoder, on the other hand, uses digital signals and is not affected by these factors.

3. Can I use a potentiometer and a quadrotor encoder together?

Yes, you can use both a potentiometer and a quadrotor encoder together. Potentiometers are often used for coarse measurements, while quadrotor encoders are used for more precise readings. Together, they can provide more comprehensive position feedback.

4. Which one is more suitable for my project, a potentiometer or a quadrotor encoder?

The answer to this question depends on the specific requirements of your project. If you need precise position feedback and have a budget for a quadrotor encoder, then it would be a better choice. However, if your project requires simpler measurements and a lower budget, a potentiometer may suffice.

5. Are there any other factors I should consider when choosing between a potentiometer and a quadrotor encoder?

Aside from accuracy and budget, other factors to consider include the type of motion being measured, the environmental conditions, and the required speed and resolution. Potentiometers are better suited for linear movements, while quadrotor encoders are better for rotational movements. Potentiometers may also be affected by temperature and humidity, while quadrotor encoders are more robust and can handle harsh environments.

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