  In this paper, based on Dynamical Systems (DS), we present an obstacle
avoidance method that take into account workspace constraint for serial
manipulators. Two modulation matrices that consider the effect of an obstacle
and the workspace of a manipulator are determined when the obstacle does not
intersect the workspace boundary and when the obstacle intersects the workspace
boundary respectively. Using the modulation matrices, an original DS is
deformed. The proposed approach can ensure that the trajectory of the
manipulator computed according to the deformed DS neither penetrate the
obstacle nor go out of the workspace. We validate the effectiveness of the
approach in the simulations and experiments on the left arm of the UBTECH
humanoid robot.
