That is the best part of getting feedback, it opens up new areas to consider and also reminds you sometimes to return to problems that are still incomplete.
这是反馈最有意思的部分，它开辟了新的思考领域，并且时常提醒您回去解决尚未处理完的问题。
2
The unactuated joints can't be controlled directly, so it is an incomplete controllable system. Smooth feedback control is invalid for such system.