 # Detected collision

• Hi guys, I'm detecting collisions in a routine. I have activated the security options to detect a torque of 16N but where the tooling is, it is more sensitive to detecting collisions than in other axes. How can I make all the robot axes equally sensitive?

• you cannot... so you need to get creative.

robot senses external forces by means of torque sensors. applied force produces torque but the amount of torque depends on distance from axis of rotation.

in simple terms this is T=F*L but keep in mind that all of them are actually vector quantities.

as a scalar product this can be expressed as

|T|=|F|*|L|*SIN(angle)

where angle is the angle between F and L. note that when F and L are parallel (or close to being parallel) torque is very small even if magnitude of F and distance L are large.

for same angle, and same force F, the greatest torque is at max distance. this is when arm is fully stretched and force is applied to most distant point on the tool. and this is where the robot is more sensitive (since fixed force is sensed as greatest amount of torque). applying same force and in same direction but acting on joint3 instead of tool would mean lower torque. it gets worse the closer you are to axis of rotation (in this case foot of the robot or joint1).