Gan Ma

Design and Development of the Humanoid Robot BHR-5:

This paper presents the mechanical and control system design of the latest humanoid robot platform, BHR-5, from Beijing Institute of Technology. The robot was developed as a comprehensive platform to investigate the planning and control for the fast responsive motion under unforeseen circumstances, for example, playing table-tennis. It has improvement on mechanical structure, stiffness, and reliability. An open control architecture based on concurrent multichannel communication mode of CAN bus is proposed to upgrade the real-time communication performance and the expansibility of the control system. Experiments on walking and playing table-tennis validate the effectiveness of the design.

The Mechanism of Yaw Torque Compensation in the Human and Motion Design for Humanoid Robots

When a humanoid robot walks fast or runs, the yaw torque is so large that the supporting foot slips easily and the robot may become unstable. The compensation for the yaw torque is important for fast humanoid walking and many studies have been focusing on yaw torque compensation. However, the issue of humanoid robot motion design that can make the movements of the robot more human-like, as well as guarantee the stability of the robot, has not been studied in-depth. In this paper, the mechanism of yaw torque compensating for human walking is firstly studied. Then we propose a method to compensate yaw torque for a humanoid robot through the motion of the arms and waist joint based on the human yaw torque compensation mechanism and ZMP stability citation. Finally, the effectiveness of the proposed method is demonstrated by the results from the simulation and walking experiments on the newly developed BHR humanoid robot.

Modeling and design of a humanoid robotic face based on an active drive points model

This study develops a face robot with human-like appearance for making facial expressions similar to a specific subject. First, an active drive points (ADPs) model is proposed for establishing a robotic face with less active degree of freedom for bipedal humanoid robots. Then, a robotic face design method is proposed, with the robot possessing similar facial appearance and expressions to that of a human subject. A similarity evaluation method is presented to evaluate the similarity of facial expressions between a robot and a specific human subject. Finally, the proposed facial model and the design methods are verified and implemented on a humanoid robot platform. Graphical Abstract

Hand-eye servo and impedance control for manipulator arm to capture target satellite safely

A crucial problem is the risk that a manipulator arm would be damaged by twisting or bending during and after contacting a target satellite. This paper presents a solution to minimize the risk of damage to the arm and thereby enhance contact performance. First, a hand-eye servo controller is proposed as a method for accurately tracking and capturing a target satellite. Next, a motion planning strategy is employed to obtain the best-fit contacting moments. Also, an impedance control law is implemented to increase protection during operation and to ensure more accurate compliance. Finally, to overcome the challenge of verifying algorithms for a space manipulator while on the ground, a novel experimental system with a 6-DOF (degree of freedom) manipulator on a chaser field robot is presented and implemented to capture a target field robot; the proposed methods are then validated using the experimental platform.

Design of a humanoid ping-pong player robot with redundant joints

This study investigates the design of a humanoid ping-pong robot system with a 7-DOFs redundant arm. The design of the arm mechanism, real-time binocular vision system, and a distributed control structure was presented. The methods for ball trajectory prediction and motion planning for the ping-pong racket were proposed. A Jacobian pseudoinverse method considering joint limits and manipulability optimization terms is employed to solve inverse kinematics in order to decrease the counterforce exerting on the humanoid robot. The proposed system is validated by a series of rally experiments between the robot and a human.

System design of an Anthropomorphic arm robot for dynamic interaction task

This paper investigates the system design of a 7-DOFs Anthropomorphic arm robot for fast dynamic interaction task, taking the ping-pong rally task against human as an example. The robot system includes the arm mechanism, real-time stereo vision sub-system, ball trajectory prediction, racket motion trajectory planning, and distributed joint controllers. The algorithms for ball identification, ball trajectory prediction, and hitting planning are presented. The validity of the system is demonstrated via rally experiments.

Bipedal walking with toe-off, heel-strike and compliance with external disturbances

Both disturbance rejection and human-like motions, like toe-off and heel-strike, are important for a biped robot to enhance its performance. However, the required motions for them may influence each other, which is why few studies consider them simultaneously. This paper presents a method to realize stable walking with toe-off and heel-strike even when the robot experiences disturbances. We propose a walking controller which can constrain the desired ground reaction force. On the one hand, the controller can adjust the torso acceleration to make the supporting leg compliant with the external disturbances on the torso. On the other hand, it can rotate the supporting foot by adjusting the ZMP to an appropriate location. The linear inverted pendulum is utilized to generate the CoM trajectory and the foot placement. Meanwhile, its ZMP can be predefined as required so that the toe-off and heel-strike can be achieved by the controller. The effectiveness of the proposed method is demonstrated by simulations.

Inverse dynamics control with acceleration optimization on a force-controlled bipedal robot

This paper presents an acceleration-based inverse dynamics method to control the floating base of a force-controlled bipedal robot. The desired accelerations of the floating base are derived by PD control in operational space and then used to calculate the accelerations of the joints. Given kinematic constraints to the feet, a relationship between the accelerations of the floating base and the desired external forces needed for those accelerations is obtained. The desired external forces are constrained by ZMP, friction and unilateral vertical forces, which introduces corresponding constraints on the accelerations. If the desired accelerations do not satisfy the constraints, quadratic programming is applied to determine optimal accelerations, which will satisfy the constraints. These optimal accelerations are used instead of the desired ones when calculating inverse dynamics. Our controller guarantees the desired external forces satisfy their constraints. The effectiveness of the proposed methods is demonstrated by tracking desired trajectories and recovering from disturbances on a force-controlled bipedal robot in simulation.

Human-like walking patterns with pelvic rotation for a humanoid robot

Fast and stable walking is one of the important prerequisite for humanoid robots to serve the people. Pelvic rotations play a significant role when one walks fast. This paper proposes a method to generate human-like walking patterns with pelvic rotation in the transverse plane for a humanoid robot to effectively improve its quickness and stability. First, the regularities of pelvic rotation in the transverse plane during human walking are studied. Second, the mechanism design of a humanoid robot waist for pelvic rotations is presented. Then, a walking trajectory planning with pelvic rotation to improve the stability margin is proposed. Finally, the effectiveness of the method is demonstrated through simulations and experiments on BHR-5.

Omnidirectional Disturbance Rejection for a Biped Robot by Acceleration Optimization

Biped robots are expected to keep stability after experiencing unknown disturbances which often exist in human daily environments. This paper presents a novel method to reject omnidirectional disturbances by optimizing the accelerations of the floating base of the robot. The optimized accelerations keep the desired external forces within their constraints and generate coordinated whole-body motion to reject disturbances from all directions. The effectiveness of the proposed method is confirmed by simulations with disturbance-rejection scenarios.