Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Help me build a servo Controller for a robotic arm

Status
Not open for further replies.

E_Frieza

Junior Member level 1
Joined
Apr 15, 2002
Messages
19
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
108
Hi There
I am trying to build a robotic arm but don't have strong enough motors(stepper or servo) the regular servos can handle about 45oz(3kg) and steppers can handle a lot less. I have some strong gear head motors that I want to use as servos (because with servos I can have absolute position control) but can't find any circuitry to convert them to servos. I also want to know if it is possible to take the circuit from the 45oz servos (futaba s148 etc.) and run the bigger gear head motors with them. Any help is very much appreciated.

Regards
 

snowman53

Junior Member level 3
Joined
Feb 7, 2002
Messages
27
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
219
servo controller schematics

They are a bit expensive, but I recommend you look at the SmartMotors from Animatics Corp.

They offer a combination brushless motor/encoder that has a RS232/RD485 addressable controller that will drive the motor to a specific position, at a constant speed, at a rate, as if it were a stepper, etc. Basically anything you might want to do with the moter can be commanded over the serial port. All the closed loop stuff is handled for you (after you tune it).

They offer a range of motor sizes & the controller by itself.

We replaced a number of applications with the smartmotor solution because of teh flexibility & easy of customization.
 

Rainbow Wizard

Junior Member level 2
Joined
Mar 3, 2002
Messages
20
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
128
lm628

Presuming you are trying t do this on your own on a low budget, try to pick up some "pancake" motors from a surplus shop. You can drive them with simple Dc power transistor amplifier.
 

Rainbow Wizard

Junior Member level 2
Joined
Mar 3, 2002
Messages
20
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
128
lm628 circuit

Presuming you are trying t do this on your own on a low budget, try to pick up some "pancake" motors from a surplus shop. You can drive them with simple Dc power transistor amplifier.
 

a40

Newbie level 1
Joined
Jun 13, 2002
Messages
1
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
8
servo driver circuits

:roll: you may to use the moment driver. It is more powerful vs servo with same size. If you do not afraide this solution, mail me.
 

Gunship

Member level 2
Joined
Dec 31, 2001
Messages
51
Helped
4
Reputation
8
Reaction score
1
Trophy points
1,288
Activity points
520
build a servo controller

You should be able to modify a servo with a bigger motor. The only catch is you have to modify the ciruit to handle much higher current to the motor. A servo is a closed loop system. If you take apart one of the R/C servo, you will see a pot on it as the feedback. (It was done that way many years ago, don't know if it still is.) This feedback gives the position of the gear. When an position is inputted into the system, the loop circuit will drive the motor until the position of the gear matches what the input is. I don't have experience on the actual circuit itself. You should get a schematic and study the drive circuit a bit. If you are lucky, all you need is to modify the drive amp with a higher power one and you are done. But keep in mind that since it is a closed loop system, any changes may cause the system to go nuts (unstable).

Hope this helps a bit. You may get lucky with some study and experiment.

Simpson
 

oldman

Junior Member level 3
Joined
Feb 21, 2002
Messages
28
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
285
lm628 cost

Building a servo using DC motors will imply some circuitry like:
- position encoder;
- motion controller;
- motor (H-Bridge) driver;
- eventually, an interface to the main controller.
You may start reading the documentation of a motion controller like LM628/629 from National Semiconductor. This will give you an idea where to begin, and how to design your servo. Personally, I used this circuit for a small project -- it did a great job for me.

OldMan
 

bunalmis

Full Member level 5
Joined
Jan 3, 2003
Messages
268
Helped
19
Reputation
38
Reaction score
11
Trophy points
1,298
Location
Ireland
Activity points
2,147
national semiconductor servo control

I thing your gear head motor is DC motor. You can use National
LM628-LM629.

These IC's are good PID servo controller.

You can use the LMD18200 H bridge driver.


www.national.com
 

yangxh

Member level 5
Joined
Nov 26, 2004
Messages
94
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
728
lmd18200 circuit sample

How does LM628-LM629 or LMD18200 cost each one?I think it's expensive.
 

tamphong

Newbie level 6
Joined
Apr 30, 2007
Messages
12
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Location
Viet Nam
Activity points
1,333
lm628 lmd18200

help me schematic of LM628 .

Added after 2 minutes:

Datasheet và Program
 

inifinitrix

Member level 4
Joined
Jul 30, 2006
Messages
72
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,288
Location
Malaysia
Activity points
1,709
servo controller absolute

i'm using lm628 too but i'm still newbie for this ic.. can someone show some circuit and example to program it.. maybe using PIC16F877a.. thanks in advance...
 

inifinitrix

Member level 4
Joined
Jul 30, 2006
Messages
72
Helped
2
Reputation
4
Reaction score
1
Trophy points
1,288
Location
Malaysia
Activity points
1,709
closed loop servo controller driver low cost

anyone? please help me..
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top