Torque Calculation for Robotic Arm

[caljuice]

Hello,

I hope I'm posting in an appropriate section. I'm trying to make a robotic arm using servos, but I'm not too sure what the max weight and lever arm length I could use. I know how to do the static torque calculations, but not too sure with the dynamic and rotational torque as the motors don't come with any data on the accelerations of the motors.

The servo I'm using for the base is Hitec 805bb which has max torque of 24.7 kg/cm and 1.78 revs per second. Although I'll probably have to slow down the servos.

For example, if I assume the lever arm is weightless and I have a mass of 0.25 kg at the end of the lever arm and the servo attached to the other end, is there any way to calculate or ball park a safe lever arm length without knowing the acceleration?

 

[tygerdawg]

You must calc for peak torque to properly size your motor.
Peak torque includes torque required for acceleration/deceleration.

If you do not do this, you may undersize your motor. You may not be able to move the load. You may be able to move it in a very erratic manner. You may not be able to maintain your positions.