1. The encoders on the Dexter arm are at the joints because that gives us the ability to compensate for backlash in the drive system. 2. The motor dance issue

1. The encoders on the Dexter arm are at the joints because that gives us the ability to compensate for backlash in the drive system. 2. The motor dance issue happens because the feedback loop on most control systems isn't fast enough. With the FPGA, our control loop is 5 MHz / 200nS so we can correct before an oscillation has time to happen. 3. Our encoders give more than 1 million CPR (clicks per revolution) so we can sense an error before it has time to become an issue that might lead to oscillation. (2 and 3) are the real magic of the arms design 4. Yes, Harmonic drives are hell. And they are not actually free of backlash, it's just "soft" e.g. they bend slightly. At this point, they are the best solutions, but we have prototypes of a cycloidal drive that costs less (in quantity) and gives us better performance. There are issues to work out, especially related to smoothness and wear, but we are making progress on it.