I require your help regarding a problem I’m encountering.
I am designing a robotic arm for agricultural use and i am having issues with the motors. We are using maxon motors however the calculated torque is larger than stall torque of all the motors within the maxon catalog.
The robot arm is approximately 8kgs and is lifting a weight of 12 grams.
Does anyone know why there may be an issue and if there are any possible solutions?
Will adding another motor in the base half the loads that are applied to each joint?
Maxon makes some of, if not the highest quality motors on the market, but they come at a price. It’s not a surprise to hear that the torque you need is beyond what they offer. 8Kg is a pretty heavy arm, though 12g is an incredibly lightweight payload.
If you have not yet built the arm and don’t need precision, consider an approach with linear actuators:
Q1) Does anyone know why there may be an issue and if there are any possible solutions?
8Kg is a medium sized robot arm. Robot arms in that weight range tend to sell for $15k and up.
It’s less about the payload than it is about the shoulder joint supporting all the other joints.
Q2) Will adding another motor in the base half the loads that are applied to each joint?
Two motors in the base will simply provide “roughly” twice the torque. It won’t help the elbow or wrist joints at all.
Can you provide a sketch or drawing or CAD of what you envision the arm to look like, and include the weights and dimensions you used for each calculation?
I attached a picture of the robot. The length of each part is 45cm, the m1 of the arm connected to shoulder is 1.985kg, the m2 is 0.6kg and at the end there will be another part of 0.5kg lifting a load of 12grams.
The second photo I attached is the servo motor ec-i-40. The calculated torque is much higher than the motor’s stall torque
Hi good day. Dear friendss … i am new in thus community… i am trying to make dc motor drive for 12v dc. Its run with 20khz and i just on the left button to run left side. If i leave Button it should stop. And if i press right button then it run to right side… i use 12v relay… but relay points burn… now i need Mosfets to drive it. Its load is 40amp … please anyone can help about it…
Thanks regards
Thank yo so much for replying! I finally used gears to decrease the torque.
Another question i have when selecting a motor, how do i choose the watt in each motor? for example how do i know if i should your EC-i-40 70W or 100W? For the selection i just checked:
1.the maximum calculated torque(including gears conversion) does not exceed the stall torque.
2. I selected a speed constant Kn>(nl+Δn/ΔΜ)/(Applied voltage)
… then you consider the current to get that torque, which will affect the choice of motor controller. You don’t need total power for making any decisions.
Note that your continuous operating torque (i.e. dynamic torque) should be <1/4 stall torque.
