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0 pointsJoel_Mckay9mo ago0 comments

In general, for some platforms each gear mechanism adds backlash precision loss, lower energy efficiency, and might not be back driven.

>Mid-price CNC milling machine

A ball-screw is mostly decorative on small machines... =3

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michaelt9mo ago

On the other hand, a 100:1 gearbox gives you much-needed torque if you're lifting a load at the end of a long arm, it makes your encoder 100x more precise (in terms of repeatability) and it makes your motor brake 100x stronger.

Back-drivability is the enemy of precision, so many robotic applications can do without it.

Joel_MckayOP9mo ago

Almost all modern servo driven units I've seen prefer to allow some compliance in the end effector. The UR5 and UR10 series for example can use force limiting control loops, and are safer to use around people.

The old "fast, cheap, or good... choose any two joke is mostly still true. =3

michaelt9mo ago

The UR10 uses 100:1 strain wave gearing in the base and shoulder joints.

You’re right that it has a freedrive mode, and force control modes. But it’s a rigid, low-backlash robot with the compliance achieved in software afterwards.

Expensive, naturally, but none of the problems that come with things like series elastic actuators.

j / k navigate · click thread line to collapse

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michaelt9mo ago

Back-drivability is the enemy of precision, so many robotic applications can do without it.

Joel_MckayOP9mo ago

The old "fast, cheap, or good... choose any two joke is mostly still true. =3

michaelt9mo ago

The UR10 uses 100:1 strain wave gearing in the base and shoulder joints.

You’re right that it has a freedrive mode, and force control modes. But it’s a rigid, low-backlash robot with the compliance achieved in software afterwards.

Expensive, naturally, but none of the problems that come with things like series elastic actuators.

j / k navigate · click thread line to collapse