Junyao Gao

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.

Gait Planning of Omnidirectional Walk on Inclined Ground for Biped Robots

When a biped robot moves about in a physical environment, it may encounter inclined ground. Biped walking on inclined ground still remains challenging for biped robots. Previous studies have discussed biped walking on inclined ground along specific directions. However, omnidirectional walk on inclined ground has rarely been investigated. In this paper, we propose a gait pattern generation method for omnidirectional biped walking on inclined ground. First, a model that describes the motion of biped walking on inclined ground uniformly with two angle parameters is proposed. A mathematical relationship between motions in the sagittal and coronal planes of the biped robot are presented. Then, based on nonorthogonal motion decoupling, a method that generates gait patterns for omnidirectional walking with a double support phase for biped robots is proposed. The trajectories of each foot are designated by the walking speed, step length, and walking direction. The motion trajectory of the center of mass (CoM) of the robot is planned using a linear inverted pendulum model in the sagittal and coronal planes. The motion of CoM in the sagittal and coronal planes is constrained in parallel to the gradient vector of the inclined ground and the horizontal plane, respectively. Finally, the effectiveness of the proposed gait planning method for biped walking on is validated by simulations and experiments with an actual biped robot.

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 Redundant Manipulator for Playing Table Tennis towards Human-Like Stroke Patterns

This study investigates the design of a 7-DOF humanoid manipulator capable of playing table tennis with human-like stroke patterns. The manipulator system includes a redundant arm, real-time stereo vision system, and a distributed motion control system. First, the size, weight, workspace, and motion capability of the designed arm are similar to those of a humans arm. The forward and inverse kinematics, and the Jacobian matrix of the redundant manipulator are formulated. Next, a distributed motion control system is designed. The ball trajectory prediction method is proposed. Then, a human-inspired optimization method based on Jacobian pseudoinverse and the comfort of the arm posture for stroke pattern trajectory is proposed to achieve human-like stroke patterns and decrease the counterforce exerted on the manipulator. Finally, the validity of the proposed system and methods is demonstrated via human-like stroke pattern experiments.

Trot pattern generation for quadruped robot based on the ZMP stability margin

Quadruped robot is expected to serve in complex conditions such as mountain road, grassland, etc., therefore we desire a walking pattern generation that can guarantee both the speed and the stability of the quadruped robot. In order to solve this problem, this paper focuses on the stability for the tort pattern and proposes trot pattern generation for quadruped robot on the basis of ZMP stability margin. The foot trajectory is first designed based on the work space limitation. Then the ZMP and stability margin is computed to achieve the optimal trajectory of the midpoint of the hip joint of the robot. The angles of each joint are finally obtained through the inverse kinematics calculation. Finally, the effectiveness of the proposed method is demonstrated by the results from the simulation and the experiment on the quadruped robot in BIT.

Research and development of throwable miniature reconnaissance robot

Throwable miniature robot can be deployed in important targets of sensitive areas by throwing, shooting, air-delivering or carrying by a small robot. So they are very suitable for secret reconnaissance and initiative detection in many military and civilian activities. However, the deployment mode of miniature mobile robots demands excellent anti-impact property. Moreover, another crucial problem resulted from the small volume of miniature robots is the difficulty of packing locomotion, sensing, computing and power subsystems into constrained space. To solve the problems above-mentioned, the design and realization for a kind of throwable miniature semi-autonomous reconnaissance robot was presented in the paper. Moreover, Finite element simulation analysis and anti-impact experiments showed that the robot has excellent capability of anti-impact. At last, the experiments also showed that the design of the throwable semi-autonomous reconnaissance robot is reliable and practical.

A Search-and-Rescue Robot System for Remotely Sensing the Underground Coal Mine Environment

This paper introduces a search-and-rescue robot system used for remote sensing of the underground coal mine environment, which is composed of an operating control unit and two mobile robots with explosion-proof and waterproof function. This robot system is designed to observe and collect information of the coal mine environment through remote control. Thus, this system can be regarded as a multifunction sensor, which realizes remote sensing. When the robot system detects danger, it will send out signals to warn rescuers to keep away. The robot consists of two gas sensors, two cameras, a two-way audio, a 1 km-long fiber-optic cable for communication and a mechanical explosion-proof manipulator. Especially, the manipulator is a novel explosion-proof manipulator for cleaning obstacles, which has 3-degree-of-freedom, but is driven by two motors. Furthermore, the two robots can communicate in series for 2 km with the operating control unit. The development of the robot system may provide a reference for developing future search-and-rescue systems.

Manipulability and stability of pushing operation by humanoid robot BHR-2

Taking pushing handcart as a typical example, this paper presents the research on arm manipulability and manipulation stability of the pushing operation by humanoid robot BHR-2. When robot moves, the waist displacement will affect hand motion without any control of arm. We propose the compensation of wrist position by analysing the relationship of hand motion and waist displacement. Considering the interaction between robot hand and the handcart, the stability control of the pushing operation based on desired pushing force is developed. Dual arm motion is realized for desired hand manipulation trajectory. Leg motion is generated off-line and the desired stable trajectory is obtained based on ZMP (Zero Moment Point) criteria. The effectiveness of arm manipulability and manipulation stability is demonstrated by simulation and experiment.

Cooperation control of multiple miniature robots in unknown obstacle environment

This article focuses on the cooperative control problem of a group of miniature mobile robots in the environment with unknown obstacles. Each robot in the group has limited sensing and communication capability. The problem is addressed by separating it into two parts. One part is the formation control of multi-robot and another is navigation control with unknown obstacles. In the first part, a flexible and fault-tolerant formation scheme is introduced. Meanwhile, the dynamic surface method is combined with backstepping sliding mode control as the tracking control law. In the navigation control part, smooth trajectory of obstacle avoidance is obtained based on limit cycle principle and distance sensor data. Finally, the effectiveness of the proposed method is verified by numerical simulations and hardware experiments carried out on the real platform.

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.