Cobot Payload & Center of Gravity (CoG) Calculator
Validate collaborative robot tool mass, combined end-effector Center of Gravity (CoG), wrist moment of inertia (kg·m²), and dynamic joint torques to prevent nuisance protective stops and joint gearbox wear.
Target Collaborative Robot Model
End-Effector (EOAT) & Workpiece Specifications
High rotational accelerations dramatically elevate dynamic torque on Joint 5 and Joint 6.
Combined Center of Gravity: 142 mm from flange. CoG is within nominal distance limit.
Wrist Joint Dynamics (J5 / J6)
The Physics of Cobot Payload & Center of Gravity (CoG)
1. The Center of Gravity Derating Curve
A collaborative robot's advertised payload (e.g., 10 kg) is only valid when the tool Center of Gravity is located within a specific envelope—typically 100mm to 150mm from the output flange:
If a long pneumatic vacuum gripper places the center of mass at 300mm on a robot rated for 150mm, the allowable payload mass is slashed by 50% to prevent joint torque overload.
2. Moment of Inertia & Nuisance Protective Stops
Mass alone does not cause collaborative robots to fault into Protective Stops during emergency stops or rapid trajectory inversions:
- Inertia Scaling: Rotational inertia scales with the square of the distance ($I = m \cdot r^2$). Extending a tool 2x further increases inertia 4x.
- Torque Observer Algorithms: Collaborative robots continuously compute expected joint torques via internal dynamic models. Excessive inertia causes torque observer mismatch, triggering false safety stops.
- Design Best Practice: Keep heavy solenoid valve manifolds and sensors mounted as close as possible to the wrist axis rather than at the tool tip.