Haifei Zhu

A Modular Biped Wall-Climbing Robot With High Mobility and Manipulating Function

High-rise tasks such as cleaning, painting, inspection, and maintenance on walls of large buildings or other structures require robots with climbing and manipulating skills. Motivated by these potential applications and inspired by the climbing motion of inchworms, we have developed a biped wall-climbing robot-W-Climbot. Built with a modular approach, the robot consists of five joint modules connected in series and two suction modules mounted at the two ends. With this configuration and biped climbing mode, W-Climbot not only has superior mobility on smooth walls, but also has the function of attaching to and manipulating objects equivalent to a “mobile manipulator.” In this paper, we address several fundamental issues with this novel wall-climbing robot, including system development, analysis of suction force, basic climbing gaits, overcoming obstacles, and transiting among walls. A series of comprehensive and challenging experiments with the robot climbing on walls and performing a manipulation task have been conducted to demonstrate its superior climbing ability and manipulation function. The analytical and experimental results have shown that W-Climbot represents a significant advancement in the development of wall-climbing robots.

Autonomous Pose Detection and Alignment of Suction Modules of a Biped Wall-Climbing Robot

Vacuum adsorption is a simple but effective attaching method widely used in many fields including robotic wall climbing. It is required that the sucker is aligned well with the target surface to form airtight chamber for vacuum generation. For applications in biped wall-climbing robots, automatically aligning the sucker with the wall is beneficial and important to enhance the efficiency and effectiveness of vacuum adsorption. Especially, such a function is essential for autonomous intelligent climbing. To this end, we propose a novel and low-cost approach to perform autonomous alignment of a sucker (suction module) based on noncontact sensors. We first develop a sensing system to detect the configuration of the swinging suction module with respect to the target surface, and then present an algorithm to compute the configuration transformation and control the robot to drive the suction cups toward the target surface with a well-aligned configuration for adherence. In this paper, the basic theory for autonomous pose detection and alignment of the suction module for wall climbing with a biped robot is presented. Specifically, the key configuration of the swinging suction module for adsorption is analyzed, and the pose detection model, the conditions for forming airtight chamber, and the autonomous alignment algorithm are introduced. Calibration of the sensing system and experiments with our biped wall-climbing robot W-Climbot is conducted. The results have verified the feasibility, effectiveness and applicability of the proposed sensing system, theoretical analysis and the algorithm for autonomous pose detection and alignment of the suction modules.

Climbot: A modular bio-inspired biped climbing robot

High-rise tasks in agriculture, forestry and building industry requires robots possessing climbing function. Motivated by these potential applications and inspired by the climbing motion of animals such as inchworms, we have developed a novel biped climbing robot - Climbot. Built with a modular approach, the robot consists of five 1-DoF joint modules connected in series and two special grippers mounted at the ends. With this configuration, Climbot is able not only to climb a variety of media, but also to grasp and manipulate objects, and hence is a “mobile” manipulator. In this paper, we first introduce the development of this novel robot, and then illustrate three climbing gaits based on the unique configuration of the robot. Experiments of climbing poles are carried out to verify the climbing functions and to demonstrate potential application of the proposed robot.

A miniature biped wall-climbing robot for inspection of magnetic metal surfaces

In order to carry out automatic ultrasonic inspection tasks, a miniature biped wall-climbing robot, the so-called MiniBibot-W, has been developed in inspiration of inchworm climbing. Developed with a modular method, this robot consists of six joint modules connected in series as the main body and two electromagnetic adhesion modules at the two ends as the two feet. An ultrasonic probe is mounted to one of the feet. MiniBibot-W thus can not only climb on magnetic surfaces with high mobility, but also perform ultrasonic inspections. In this paper, the development of the robotic system is first presented, and then three climbing gaits and inspection action are introduced. Driving force and adhesion force are analyzed to ensure the safety during climbing and manipulating procedure. A series of experiments are conducted to verify the feasibility and effectiveness of the proposed robotic system and the analysis. A potential application with MiniBibot-W is also demonstrated in ultrasonic detection.

W-Climbot: A modular biped wall-climbing robot

Although a large number of wall-climbing robots have been developed in the past decades, most of them suffer from shortcomings such as poor ability to omni-directional locomotion, lower capability to transit between walls and to negotiate obstacles on the walls. To overcome these drawbacks, we have developed a novel biped wall-climbing robot - W-Climbot using modularization method. Consisting of an arm as the main body and two vacuum suckers at the two ends, W-Climbot has great mobility on walls and potential manipulation function. In this paper, the development of W-Climbot is briefly introduced, and then the suction force model for suction module design is presented. The superior ability to transit between walls and to traverse and step over obstacles is analyzed. Experiments are carried out to verify the effectiveness of the system design and to demonstrate basic features of the novel robot.

A biologically inspired miniature biped climbing robot

Inspired by the motion patterns of inchworms, a miniature biped climbing robot is developed with modularization method for some tedious and dangerous high-rise tasks. This inchworm-like mini-robot consists of several modules including I-typed joint modules, T-typed joint modules, and gripper modules, which are all driven by small RC servo motors. In this paper, the development of the robot prototype with biomimetic and modular methods is presented, and two feasible gaits of the mini-robot are proposed for climbing poles, trees and trusses. The climbing ability of such biped robot is verified through simple experiments. It is shown that the locomotion function of some biped climbing animals such as inchworms can be easily implemented by simple mechatronic systems.

Collision-free single-step motion planning of biped pole-climbing robots in spatial trusses

For a biped pole-climbing robot (BiPCR) with dual grippers to climb poles, trusses or trees, a feasible collision-free climbing path is inevitable. In this paper, we utilize the sampling-based algorithm, Bi-RRT, to plan a feasible single-step collision-free climbing motion for BiPCRs in spatial trusses. Under the orientation limit of a 5-DoFs BiPCR, a new state representation along with corresponding operations including sampling, metric calculation and interpolation is presented. A simple but effective model of BiPCRs in trusses is proposed, through which the climbing path planning problem is transformed to be similar to that of an industrial robot. In addition, the pre- and post- processes are introduced not only to expedite the convergence of the Bi-RRT, but also to ensure the safe movement for the robot near the poles. The effectiveness and efficiency of the presented Bi-RRT algorithms for climbing motion planning are verified in the simulation.

Stability of biped robotic walking with frictional constraints

Tipping-over and slipping, which are related to zero moment point (ZMP) and frictional constraint respectively, are the two most common instability forms of biped robotic walking. Conventional criterion of stability is not sufficient in some cases, since it neglects frictional constraint or considers translational friction only. The goal of this paper is to fully address frictional constraints in biped walking and develop corresponding stability criteria. Frictional constraints for biped locomotion are first analyzed and then the method to obtain the closed-form solutions of the frictional force and moment for a biped robot with rectangular and circular feet is presented. The maximum frictional force and moment are calculated in the case of ZMP at the center of contact area. Experiments with a 6-degree of freedom active walking biped robot are conducted to verify the effectiveness of the stability analysis.

Joystick-based Control for a Biomimetic Biped Climbing Robot

A joystick-based control method is studied for Climbot,which is a novel 5-DoF(degree of freedom) biomimetic biped climbing robot.The kinematics and the available grasping area of the robot are analyzed firstly.And then,according to the characteristics of the robot biped climbing by switching its fixed-gripper,an intuitional joystick-based operating mode is proposed,in which different operating coordinates are defined for corresponding climbing gaits,and a matrix transform algorithm is presented to keep the robot coordinate system unchanging after switching its fixed-gripper.Finally,road-pole climbing experiments with three gaits(including inchworm-like,turning-around and turning-over gaits) and an application demonstration are carried out to verify the effectiveness of the presented joystick-based control method.

The superior mobility and function of W-Climbot — A bio-inspired modular biped wall-climbing robot

W-Climbot is an inchworm-like biped wall-climbing robot we developed with a modular approach. Consisting of five joint modules and two suction modules, the robot is actually a mobile 5-DoF manipulator with dual sucking end-effectors at the two ends. With this kinematic structure and biped climbing mode, W-Climbot has superior wall-climbing function (great ability to omni-directional locomotion, to negotiate obstacles on the walls and to transit between walls) and manipulation function. In this paper, the robot system is first introduced, suction force in one critical case is analyzed for climbing reliability and safety, and three climbing gaits are presented. To illustrate its superior 3-D mobility, a series of experiments (climbing on a vertical exterior surface with different gaits, negotiating obstacles, and transiting among interior surfaces) are carried out. Performing a pick-and-place task on a wall is also demonstrated as one of its the potential applications. The results show that W-Climbot is a significant advancement in development of wall-climbing robots.