Motor and a controller for a robotic arm

This is my first post here, so hello all. I really hope I can learn a lot from you guys.

I am trying to build a robotic arm to carry an object and put it inside of different boxes that are placed in different fixed locations.

I found a few robotic arms that can do it, but I am still trying to find the right motor for the job. I read a lot on-line about the different motors, but I am not sure which on to pick. Since the boxes are located in fixed places, the motors have to

move in a precise way, so, according to my research, Servo motors are the ones I should use.

Since it is a low budget project (I am college student), I wasn’t sure which motor to choose (there are a lot of servo motors out there). I found several Servo motors on-line, for example , Analog Feedback Servo, and I was wondering what is the best servo motor I can buy for a really low cost project? I think I can spend about 10-20$ per motor (I need 5 motors).

I already have an Rpi and I know that pin 18 is the PWM pin that controls the motor’s precision movement, but before I purchase a PWM controller and additional motors I need to run some testing to find how precise the motor is. What is the recommended controller for this kind of project. ( I only need 5 -6 motors).

By the way, how can I calculate the amount of weight the motor can handle?

Any ideas and information will be greatly appreciated.

Thank you

This should help: robotshop.com/blog/en/robot- … lator-9712
The servo at the shoulder will be subjected to the highest load / torque, so you might want to spend more on that.
Have you determined what design you’ll go with? Create a sketch if you can and provide dimensions.