Servos For Robotic Arm

Hello to everyone.I want to make an Arduino robotic arm and i am wondering if this wiring diagram is correct.I make it myself from what i have seen from internet.Tell me your opinion, please.

i will use this

Should be ok from my quick look at it, with one caveat:

Breadboards are typically rated at only 1 amp total per trace; if you are operating all six servos at the same time, your power traces are going to see somewhere around 4 to 6 amps. Most standard sized servos can draw up to an amp, sometimes more - when under load.

So - you might want to measure what your servos draw first (or look at their datasheets if you have them), before plugging them into a breadboard (if you plan to follow that diagram of your's exactly).

Otherwise, build a perfboard with some 3-pin headers for each servo, and solder the power traces together properly, with a thicker wire (and solder) to beef-up the current handling capability.

Other than that, it should be ok (your servo power supply is sized well, btw).

Good luck, and I hope your project turns out well!

:)

cr0sh: Should be ok from my quick look at it, with one caveat:

Breadboards are typically rated at only 1 amp total per trace; if you are operating all six servos at the same time, your power traces are going to see somewhere around 4 to 6 amps. Most standard sized servos can draw up to an amp, sometimes more - when under load.

So - you might want to measure what your servos draw first (or look at their datasheets if you have them), before plugging them into a breadboard (if you plan to follow that diagram of your's exactly).

Otherwise, build a perfboard with some 3-pin headers for each servo, and solder the power traces together properly, with a thicker wire (and solder) to beef-up the current handling capability.

Other than that, it should be ok (your servo power supply is sized well, btw).

Good luck, and I hope your project turns out well!

:)

Hello cr0sh,

I will use 4x MG996R Servos and 2x MG995

For the MG996R say this: Features: Gear Type: All Metal Gears Operating Speed: 0.17sec / 60 degrees (4.8V no load) Operating Speed: 0.13sec / 60 degrees (6.0V no load) Stall torque:12kg/cm(6V) Operation Voltage : 4.8 - 7.2 V Temperature range: 0¡æ to 55¡æ Power Supply: Through External Adapter Stable and Shock Proof. - Metal Gear - Connector Wire Length 300mm Compliant with most standard receiver connector: Futaba, Hitec, Sanwa, GWS etc... Great for truck, Boat, Racing Car, Helicopter and Airplane

For the MG995 say this: Features : Dimensions:1.57 x 0.79 x 1.44 (40 x 20 x 36.5mm) Weight 1.78oz 48g (Servo Net Weight Only) Operating Speed (4.8V no load) 0.17sec 60 degrees Operating Speed (6.0V no load) 0.13sec 60 degrees Stall Torque (4.8V) (13kgcm) (180ozin.) Stall Torque (6.0V) (15kgcm) (208ozin.) Temperature Range -30 to +60 Degree C Dead Band Width 4usec Operation Voltage : 3.5 - 8.4Volts

I think that i will be ok with my diagram.

jack1992: I think that i will be ok with my diagram.

Yeah - but neither of those specifications tell you anything about the current, nor any values to use to calculate it (you need more than just voltage).

As I noted before, a single standard servo under load can pull one amp, maybe more; at startup it definitely will pull more than one amp. If all six servos move at one time, you'll be pulling somewhere around 6 amps.

The traces on most prototyping breadboards are only rated to about one amp total; 2 amps would be pushing it.

It would be best if you set up your robot arm with the servos positioned as needed, and then measure the current consumption for each servo moving the load assigned to it. This way you'll know what you're dealing with.

Or don't. Maybe you'll get lucky. Or, maybe you'll make fire. Either way, it'll probably be an exciting time...

Hello cr0sh,

i searched on the internet and i found this for the MG966R

Weight: 55 g
Dimension: 40.7 x 19.7 x 42.9 mm approx.
Stall torque: 9.4 kgf·cm (4.8 V ), 11 kgf·cm (6 V)
Operating speed: 0.17 s/60º (4.8 V), 0.14 s/60º (6 V)
Operating voltage: 4.8 V a 7.2 V
Running Current 500 mA - 900 mA (6V)
Stall Current 2.5 A (6V)
Dead band width: 5 µs
Stable and shock proof double ball bearing design
Temperature range: 0 ºC – 55 ºC

For the MG995 see the image.What is your advice?

I'd maybe recommend MG958 servo's over mg996r. The mg996r's seem to have quite a bit of dead band width (around 10us) while the mg958 states around 1us. It says its an upgraded version of of the mg996r to.

I currently don't have one to test but the mg996r's downside for the ones i have is not being able to move in degree's smaller than 10 degree's of change without using a higher angle to move the arm.

Example: Set servo to 0 degree's then to 90 degree's. It moves accordingly. Tell servo to move to 95 degree's and it doesn't move. Tell it to move to 100 degree's and not much movement. 100+ it starts moving correctly.

I have some some towerpro mg90s micro servo's and when I tell it to move 1 degree higher or lower it moves. Probably wouldn't recommend mg996r for robots but even for like airplane rudders or w/e it wouldn't have fine control.

jack1992: Running Current 500 mA - 900 mA (6V) Stall Current 2.5 A (6V)

Six of these, if all start up from a dead start moving a load (which is essentially "starting at stall conditions") will pull for a brief period approximately 15 amps. This is well beyond the capabilities of the breadboard, as well as that of you power supply (in your diagram).

Even the running current (not to mention whatever the "loaded running current" will be) for each servo - when added together for multiple servos running - is going to be very large; larger than what I would trust a breadboard to work with.