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Why do robots rely so much on gears? There is no gear in the animal kingdom, and yet their limbs are vastly more energy efficient and agile, aren't they?
by grondilu 9y ago
Why do robots rely so much on gears? There is no gear in the animal kingdom, and yet their limbs are vastly more energy efficient and agile, aren't they?
- jpm_sd 9y agoAlas, there is no muscle in the robot kingdom! A lot of interesting work has been done recently on direct drive or minimally geared legged robots, however - check out Ghost Robotics for an example. [https://www.ghostrobotics.io/ https://www.ghostrobotics.io/]
- mattnewton 9y agoThere are no muscles on mars either though. NASA has a different set of constraints than nature (one of them being human lifespans of time to make a workable solution).
- thearn4 9y agoIs there a biological analog of gear ratios? A nice thing about mechanical gearing is the ability to trade off speed and torque on the fly.
- foxylad 9y agoThe length of the lever. For speed, long legs. For torque, short jaws.
- pixl97 9y agoMuscles/limbs are only 'vastly' more efficient if you consider they have large numbers of nano scale support systems constantly rebuilding them. Since we don't have nanobots, gears will be better for machines. Also, nature didn't naturally develop a axle.
- LeifCarrotson 9y agoRobots have bearings and simple, efficient rotary electric motors. A machinists lathe is a fantastic piece of technology. We're really good at building things that rotate. Nature uses cellular-scale nanotechnology to build millions of microscopic linear motors. We can build linear electric motors by essentially unrolling the stator, but they're on a much larger scale. We get better results with servomotors, either installed with some gear reduction at a pivot joint, or hooked to a ballscrew linear actuator.
- vacri 9y agoMuscles/limbs also don't power-down for long periods. They're in need of constant maintenance (energy, food; waste removed) or they rot.
- PhasmaFelis 9y agoIs that an inherent property of muscle-like mechanisms, or just several billion years' worth of environmental bacteria evolved to consume living tissue if not constantly opposed by a immune system?
- infinite8s 9y agoThat's an inherent property of all living material. All tisssue is on the edge of thermodynamic breakdown i.e. Unlike manufactured material, resting state for biology is death).
- wingspar 9y agoThere are functioning gears in the animal kingdom: juvenile Issus insects have their rear hind leg movement synchronized with gearing. http://www.cam.ac.uk/research/news/functioning-mechanical-gears-seen-in-nature-for-the-first-time http://www.cam.ac.uk/research/news/functioning-mechanical-ge...
- cbames89 9y agoThere is atleast one animal that uses gears as part of their locomotion: http://www.npr.org/2013/09/13/219739500/living-gears-help-this-bug-jump http://www.npr.org/2013/09/13/219739500/living-gears-help-th...
- tlb 9y agoElectric motors can't generate the torque to drive something like a knee joint, without being very large and heavy. Motor torque is limited by the current you can run through copper wire, times the magnetic field you can generate with permanent magnets. The best motors are only about 2 Nm / kg (continuous torque / motor weight). A knee joint requires torque around (weight of robot/2 * length of tibia) in order to squat, say 100 nM for a human-sized robot. Direct-drive motors would weigh 50 kg each! So in practice, you use a 20:1 gearbox and 2.5 kg motors. Superconductors could totally change that some day.
- vacri 9y agoAgility varies quite a lot. For example, a pick-and-place robot's arm has more agility than a grasshopper's hind leg, as that leg is pretty limited in its movement.