Zhangguo Yu

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.

Design and similarity evaluation on humanoid motion based on human motion capture

This paper explores the design of humanoid complicated dynamic motion based on human motion capture. Captured human data must be adapted for the humanoid robot because its kinematics and dynamics mechanisms differ from those of the human actor. It is expected that humanoid movements are highly similar to those of the human actor. First, the kinematics constraints, including ground contact conditions, are formulated. Second, the similarity evaluation on the humanoid motion based on both the spatial and temporal factors compared with the human motion is proposed. Third, the method to obtain humanoid motion with high similarity is presented. Finally, the effectiveness of the proposed method is confirmed by simulations and experiments of our developed humanoid robot “sword” motion performance.

Dynamic model based ball trajectory prediction for a robot ping-pong player

In this paper, a novel ball trajectory prediction method is proposed for a robot ping-pong player. The method is based on the dynamic model in the sky and the bouncing dynamic model between the ball and the table. First, the ambiguity of the dynamic model in the sky is removed. Then, the bouncing model between the ball and the table is proposed to get the relationship of the emergence speed and the incidence speed. The corresponding coefficients of models are trained according to the 3D Cartesian coordinates of the ball calculated from a high speed stereo vision system. With known dynamic models, the trajectory can be predicted if several initial trajectory points of the ball from the vision system are given. Experiments show that the trajectory is able to be predicted accurately in several milliseconds. The result of our method is better than that by LWR based approach.

Distributed Control System for a Humanoid Robot

A humanoid robot generally has more than thirty DOFs to be controlled in real-time and needs to deal with information of multiple sensors such as encoders, force, gyro, acceleration and vision sensors. Therefore an effective control system is crucial for the humanoid robot. In this paper, we propose a distributed control architecture for humanoid robots based on the combination of Memolink and CAN bus. This architecture consists of a vision and hearing processing sub-system for vision information processing, a tele-operation sub-system and a realtime motion control sub-system. The operating systems of this architecture are composed of Windows and RT-Linux. The Windows OS is used as the operating system of the former two subsystems to process multimedia and tele-operation information tractably. Linux and real-time RT-Linux OS are used as the operating system of motion control sub-system to achieve the realtime control capability. The biped walk experiments show that this control architecture is effective, reliable and tractable.

Flexible foot design for a humanoid robot

Since a biped robot tends to tip over easily due to impacts, rough terrain or obstacle object, stable and reliable biped walking is a very important achievement. Well designed foot plays a crucial role in stabilization control for a humanoid robot. In this paper, we present a flexible foot design for our humanoid robot, including a landing impact absorption mechanism and a foot attitude estimation system. First, the mechanical design of the flexible foot is proposed. Rubber bushes and rubber pads are adopted for absorbing impacts. Then, the implementation of hardware and software for the foot attitude estimation system is presented. MEMS accelerometer and angular rate gyroscopes operate as dynamic inclination measurement sensors and a DSP is used for signal collecting and processing. Finally, the effectiveness of the developed flexible foot is confirmed by several experiments.

Computer control system and walking pattern control for a humanoid robot

A humanoid robot generally has more than thirty DOFs to be controlled in real-time and needs to deal with information of multiple sensors such as encoders, force and moment sensors, inertial attitude sensors and vision sensors. Therefore an effective control system is crucial for the humanoid robot. In this paper, we propose a distributed computer system consisting of the online planning sub-system and the real-time motion control sub-system based on CAN bus and Ethernet for humanoid robots. CAN bus is used for distributed real-time motion control and Ethernet is used for non-real-time and large data quantities communication between the online planning and motion control sub-systems. The Windows and RT-Linux are used as operating systems for the online planning and motion control sub-systems respectively. The walking pattern control modifies the planned walking pattern based on sensory information when there are unexpected sudden events. The effectiveness of our proposed computer system and walking pattern control method was confirmed by walking experiments on our newly-built humanoid robot.

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.

Robust push recovery by whole-body dynamics control with extremal accelerations

This paper presents a whole-body dynamics con- troller for robust push recovery on a force-controlled bipedal robot. Using Featherstones spatial vector method, we reveal a relationship between the accelerations of the floating base and the desired external forces needed for those accelerations. Introducing constraints on the desired external forces causes corresponding constraints on the accelerations. Quadratic pro- gramming is applied to find the extremal accelerations, which recover the robot from pushes as best as it can. Using the proposed robustness criterion, our method is robuster than presented methods. The effectiveness of the proposed method is demonstrated by recovering from pushes in simulation.

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

An improved ZMP trajectory design for the biped robot BHR

An improved ZMP (Zero Moment Point) trajectory for a biped robot is designed in this paper, which imitates a humans actual ZMP trajectory in the walking process. A new method of walking pattern generation based on forward moving ZMP in SSP (Single Support Phase) is also provided. It can keep the ZMP moving forward instead of staying in the center of supporting region during SSP, which is helpful for increasing the walking speed. We have been developing BHR, which has 38 DOFs (degree of freedom). The effectiveness of the method is conducted by simulation and walking experiment on BHR.