Abstract
A humanoid manipulator produces significantly reactive forces against a humanoid body when it operates in a rapid and continuous reaction environment (e.g., playing baseball, ping-pong etc.). This not only disturbs the balance and stability of the humanoid robot, but also influences its operation precision. To solve this problem, a novel approach, which is able to generate a minimum-acceleration and continuous acceleration trajectory for the humanoid manipulator, is presented in this paper. By this method, the whole trajectory of humanoid manipulation is divided into two processes, i.e., the operation process and the return process. Moreover, the target operation point is considered as a particular point that should be passed through. As such, the trajectory of each process is described through a quartic polynomial in the joint space, after which the trajectory planning problem for the humanoid manipulator can be formulated as a global constrained optimization problem. In order to alleviate the reactive force, a fitness function that aims to minimize the maximum acceleration of each joint of the manipulator is defined, while differential evolution is employed to determine the joint accelerations of the target operation point. Thus, a trajectory with a minimum-acceleration and continuous acceleration profile is obtained, which can reduce the effect on the body and be favourable for the balance and stability of the humanoid robot to a certain extent. Finally, a humanoid robot with a 7-DOF manipulator for ping-pong playing is employed as an example. Simulation experiment results show the effectiveness of this method for the trajectory planning problem being studied.
Highlights
The trajectory planning of a humanoid manipulator is a fundamental research issue in humanoid robotics and is very important for robots serving the human[1, 2]
Since each of the path points in the Cartesian space ought to be mapped into a set of joint angles, with these sets of joint angles interpolated with smooth functions within all the kinematic constraints of the manipulator[3], Cartesian space planning should involve a large amount of inverse kinematics computation[4]
In the MJTP-differential evolution (DE) method, the quartic polynomial is used to interpolate the joint trajectory of the whole motion, while the fitness function of DE is transformed into the following formula (25) when the trajectory satisfies all kinematic constraints of the humanoid manipulator
Summary
The trajectory planning of a humanoid manipulator is a fundamental research issue in humanoid robotics and is very important for robots serving the human[1, 2]. Wang et al presented a smooth, minimum-acceleration trajectory planning (MATP) method within the velocity and acceleration constraints of a humanoid robot, which can find MATP from the arbitrary initial state to the arbitrary target state within a determined time frame[3]. A trajectory optimization method for a humanoid manipulator, based on differential evolution (DE), is presented in order to alleviate the reactive force against the humanoid body. It divides the whole trajectory of the humanoid manipulation into two stages, i.e., the operation process and the return process, with the target operation point being a particular point that should be passed through. By obtaining a trajectory with a minimum-acceleration and continuous acceleration profile, this approach method is more efficient for the trajectory planning problem
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
