Before revision:  To solve these problems , we propose a simple and effective stiffness estimation method that estimates a complete end-effector stiffness matrix from the variation of demonstrations.
After revision:  To solve these problems , we propose a DMP-based framework that learns and generalizes variable impedance manipulation skills from human demonstrations. This framework improves robots' adaptability to environment changes(i.e. the weight and shape changes of the robot end-effector stiffness matrix from the variation of demonstrations.