Pardon my butting in. I've had a read through the forum and was wondering if any progress has been made on the force sensing issue, in terms of practical results?
I had a few thoughts on the topic that I would like to share.:
1.) The minimum grip depends on the weight and surface friction of the object trying to be lifted. We naturally adjust our grip if we see/feel that the object is slipping. When an object slips, it generates vibrations which can be measured and quantified. This is susceptible to noise, but is still viable with adequate filtering.
2.) The maximum grip force depends on the mechanics of the hand and the maximum force that can be applied by the actuators/motors. Is there any data or testing which could find the maximum?
3.) Depending on how much force can realistically be exerted by the hand, there may be a "sweet spot" for the grip strength which covers a range of scenarios, and could be a good starting point or default value.
4.) Haptic feedback could play a role here. Firstly by providing feedback in terms of pressure and secondly by amplifying the vibrations caused by slipping. This is probably out of the scope of this particular problem, but this approach allows the brain the handle a large chunk of the computational requirement and can adapt with practice.