Calculate holding torque, dynamic load, and motor sizing. Test reach, payload, efficiency, and gearbox assumptions. Compare joint requirements clearly before selecting actuators and components.
| Parameter | Example Value |
|---|---|
| Link lengths | 0.45 m, 0.35 m, 0.20 m |
| Link masses | 3.0 kg, 2.1 kg, 1.2 kg |
| Payload mass | 1.8 kg |
| Joint angles | 35°, 25°, -10° |
| Angular accelerations | 60, 45, 90 deg/s² |
| Safety factor | 1.40 |
| Required joint torques | 53.2807 N·m, 18.1122 N·m, 6.2037 N·m |
| Required motor torques | 0.7835 N·m, 0.3551 N·m, 0.1513 N·m |
These values match the default calculator inputs and provide a quick benchmark for testing the file after deployment.
This calculator models a three-link planar robot arm moving in a vertical plane. It estimates static torque from gravity and added downward force, then adds a simple dynamic term from angular acceleration.
φ1 = θ1φ2 = θ1 + θ2φ3 = θ1 + θ2 + θ3
j:τg,j = -Σ(Wi × xi,j)Wi is each downward load and xi,j is its horizontal offset from the joint axis.
τa,j = Ij × αjτtotal,j = τg,j + τa,jRequired joint torque = |τtotal,j| × safety factorRequired motor torque = required joint torque / (gear ratio × efficiency)
It estimates gravity torque, acceleration torque, required joint torque, motor torque after gearing, and approximate power for a three-link robot arm.
It covers both. Gravity torque represents holding load, while the acceleration term adds a simple motion-based torque estimate for faster sizing checks.
Each upstream joint supports more mass and longer moment arms. That is why base joints usually need far more torque than wrist joints.
The center of mass ratio locates each link mass along its length. A value of 0.50 places the link center of mass at midspan.
A gearbox multiplies torque at the joint. The motor therefore supplies less torque, although efficiency losses and speed tradeoffs still matter.
Yes. Each joint has its own efficiency input. Lower efficiency increases the required motor torque and raises estimated power demand.
Yes, for early sizing. It best matches a planar articulated arm in a vertical plane. Complex spatial robots need a full dynamics model.
Torque depends on horizontal offset from each joint. As the arm posture changes, moment arms change, so torque rises or falls.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.