MotorLab sizing suite
Inertia mapping
Estimate required torque and speed for rotating or linear axes. Use the helper if you need to calculate load inertia for common shapes.
Inputs
Load inertia, J_L
kg*m^2
Gear ratio, N (motor:load)
Motor-to-load gear ratio, dimensionless.
Gear efficiency
Gearbox efficiency, dimensionless.
Static friction torque @ load
Nm
External torque @ load
Nm
Target peak speed @ load
rad/s
Accel time
s
Decel time
s
Constant speed time
s
Results
Key resultsRequired motor performance
Required continuous torque
0.142Nm
Required peak torque
0.254Nm
Required speed
382RPM
Use these results to find motors
All results
Reflected load inertia, J_L,ref
0.00001
kg*m^2Total equivalent inertia, J_eq
0.00051
kg*m^2Motor peak speed
40
rad/sMotor peak speed
382
RPMTotal move time
0.7
sLoad angular accel
200
rad/s^2Motor angular accel
400
rad/s^2Accel torque (inertia only)
0.204
NmLoad-side resistive torque
0.1
NmMotor-side resistive torque
0.05
NmPeak accel torque @ motor
0.254
NmPeak decel torque (regen)
0.254
NmMotor torque @ constant speed
0.05
NmMotor mechanical power @ peak speed
2
WRMS torque
0.142
NmRequired continuous torque
0.142
NmRequired peak torque
0.254
NmInertia ratio (load:motor)
0.02
Inertia mapping - Rotational axis
Inputs
| Item | Value | Unit |
|---|---|---|
| Load inertia, J_L | 0.00004 | kg*m^2 |
| Motor rotor inertia, J_M | 0.0005 | kg*m^2 |
| Gear ratio, N (motor:load) | 2 | |
| Gear efficiency | 1 | |
| Static friction torque @ load | 0.1 | Nm |
| External torque @ load | 0 | Nm |
| Target peak speed @ load | 20 | rad/s |
| Accel time | 0.1 | s |
| Decel time | 0.1 | s |
| Const-speed time | 0.5 | s |
| Ambient/cooling factor, k_th | 1 |
Key results
| Item | Value | Unit |
|---|---|---|
| Required continuous torque | 0.142 | Nm |
| Required peak torque | 0.254 | Nm |
| Required speed | 382 | RPM |
Outputs
| Item | Value | Unit |
|---|---|---|
| Reflected load inertia, J_L,ref | 0.00001 | kg*m^2 |
| Total equivalent inertia, J_eq | 0.00051 | kg*m^2 |
| Motor peak speed | 40 | rad/s |
| Motor peak speed | 382 | RPM |
| Total move time | 0.7 | s |
| Load angular accel | 200 | rad/s^2 |
| Motor angular accel | 400 | rad/s^2 |
| Accel torque (inertia only) | 0.204 | Nm |
| Load-side resistive torque | 0.1 | Nm |
| Motor-side resistive torque | 0.05 | Nm |
| Peak accel torque @ motor | 0.254 | Nm |
| Peak decel torque (regen) | 0.254 | Nm |
| Motor torque @ constant speed | 0.05 | Nm |
| Motor mechanical power @ peak speed | 2 | W |
| RMS torque | 0.142 | Nm |
| Required continuous torque | 0.142 | Nm |
| Required peak torque | 0.254 | Nm |
| Inertia ratio (load:motor) | 0.02 |