Advanced Robotics

Park, Ill-Woo; Kim, Jung-Yup; Oh, Jun-Ho

doi: 10.1163/156855308X292538pmid: N/A

The authors propose a simple on-line method for generating a walking pattern for the biped humanoid robot KHR-3 (HUBO). The problem of realizing a walking action in humanoid robots involves two components: generation of the basic walking pattern and the compensation required to maintain the robot's balance. Dynamic walking can be realized by incorporating the real-time stabilizing control algorithm developed for KHR-1, KHR-2 and KHR-3. The walking pattern of KHR-3 has four modes: forward/backward, left/right, curved walking and turning around. In the previous pattern generation of the KHR series, the step time and stride of the robot were fixed, and the walking modes, step time and action of stride without stopping could not be changed. Hence, the flexibility of the walking pattern of the robot needed to be upgraded. The walking pattern in this paper allows variation in the walking mode, step time and stride for each step. The pattern uses a simple mathematical form of trajectory curves, specifically the sine, cosine, linear and third-order polynomial curves, and the superposition of these curves is used to minimize the complexity and burden of the computation. The authors used a third-order polynomial to generate the trajectory of the robot's pelvis. With the aid of a simplified zero-moment point (ZMP) equation, the pelvis trajectories have a direct relationship with the ZMP trajectories. An effective means of generating the trajectories is introduced, and the scheme is verified experimentally under various walking conditions that take into account the step time and stride. The experimental platform, which has human-like features and movement, is briefly introduced here. With a simple kinematical structure and distributed control hardware architecture, the platform was designed to consume relatively low levels of energy. Moreover, the scheme for generating the trajectory is realized for variations to flexible walking.

Fujii, Norisuke; Ota, Jun

doi: 10.1163/156855308X292547pmid: N/A

We address multiple-robot rearrangement problems in this paper. The rearrangement of multiple objects is a fundamental problem involved in numerous applications. In this case, it must be considered that a rearrangement task has constraints regarding the order of the start, grasping and finish time of transportation. Attention to these constraints makes it possible to rearrange rapidly; however, the calculation of the constraints is costly in terms of computation. In this paper, we propose a rearrangement method that calculates constraints efficiently. We analyze constraints and classify them into two groups: those that require less computational cost and those that require more. Robots do not calculate all groups at the same time — the time required for each type of calculation varies. The proposed method is tested in a simulated environment 96 times in six kinds of working environments with up to four mobile robots. Compared to the method that calculates all constraints at the same time, the robots' inactive time is significantly reduced and the total time for task completion is also eventually reduced. The proposed method is incomplete, but can be used to perform most rearrangement problems in a short time.

Gallardo-Alvarado, J.; Rodríguez-Castro, R.; Islam, Md Nazrul

doi: 10.1163/156855308X292556pmid: N/A

In this work the forward position analysis (FPA) of 3-RS structures (R, S, P and C = revolute, spherical, prismatic and cylindrical, respectively) is carried out applying recursively the Sylvester dialytic elimination method. The analytical solution provided in this contribution yields 16 possible poses of the moving platform given the limb lengths of the manipulator and it is applicable to a wide class of parallel manipulators, e.g., the 3-RP*S mechanism, 3-CP*S mechanism, 6–3 Gough–Stewart platforms and 3-RR*S mechanism. A case study is included which consists of solving the FPA of a 3–3 Gough–Stewart platform, also known as an octahedrical mechanism.

Ramadan, Ahmed; Inoue, Kenji; Arai, Tatsuo; Takubo, Tomohito

doi: 10.1163/156855308X292565pmid: N/A

This paper presents the synthesis and design optimization of a compact and yet economical hybrid two-fingered micro–nano manipulator hand. The proposed manipulator hand consists of two series modules, i.e., an upper and lower modules. Each of them consists of a parallel kinematics chain with a glass pipette (1 mm diameter and 3–10 cm length) tapered to a very sharp end as an end-effector. It is driven by three piezo-electric actuated prismatic joints in each of the three legs of the parallel kinematics chain. Each leg of the kinematics chain has the prismatic–revolute–spherical joint structure. As the length of the glass pipette end-effector is decreased, the resolution and accuracy of the micro–nano manipulator hand is increased. For long lengths of the glass pipette end-effector, this manipulator works as a micro manipulator and for short lengths it works as a nano manipulator. A novel closed-form solution for the problem of inverse kinematics is obtained. Based on this solution, a simulation program has been developed to optimally choose the design parameters of each module so that the manipulator will have a maximum workspace volume. A computer-aided design model based on optimal parameters is built and investigated to check its workspace volume. Experimental work has been carried out for the purpose of calibration. Also, the system hardware setup of the hybrid two-fingered micro–nano manipulator hand and its practical Jacobian inverse matrices are presented.

Diao, Xiumin; Ma, Ou

doi: 10.1163/156855308X292574pmid: N/A

This paper addresses workspace determination of general 6-d.o.f. cable-driven parallel manipulators with more than seven cables. The workspace under study is called force-closure workspace, which is defined as the set of end-effector poses satisfying the force-closure condition. Having force-closure in a specific end-effector pose means that any external wrench applied to the end-effector can be balanced through a set of non-negative cable forces under any motion condition of the end-effector. In other words, the inverse dynamics problem of the manipulator always has a feasible solution at any pose in the force-closure workspace. The workspace can be determined by the Jacobian matrix and, thus, it is consistent with the usual definition of workspace in the robotics literature. A systematic method of determining whether or not a given end-effector pose is in the workspace is proposed. Based on this method, the shape, boundary, dimensions and volume of the workspace of a 6-d.o.f., eight-cable manipulator are discussed.

Jia, Songmin; Sheng, Jinbuo; Shang, Erzhe; Takase, Kunikatsu

doi: 10.1163/156855308X292583pmid: N/A

In this paper, a novel method of obstacle recognition and localization for mobile robots using radio frequency identification (RFID) technology and stereo vision is proposed. It is inexpensive, flexible and easy to use in practical environments. As information about the obstacles or environment can be written in ID tags, the proposed method can detect the obstacles easily and quickly compared with other methods. RF is not so stable, so the Bayes rule was introduced to calculate the probability where the ID tag exists in order to improve the accuracy of localizing obstacles with the ID tags. Then the stereo camera starts to process the image of the region of interest where the obstacle exists. The proposed method does not need to process all the image and easily gets some information about obstacles such as size, and color, and thus decreases the processing computation. Research on RFID technology integrating stereo vision to localize an indoor mobile robot has also been performed. This paper introduces the architecture of the proposed method and some experimental results.

Liu, H.; Sun, K.; Xie, Z. W.; Huang, J. B.; Jiang, Z. N.; Jin, M. H.; Liu, Y. W.

doi: 10.1163/156855308X292592pmid: N/A

The paper puts forward the concept of the Satellite On-Orbit Self-Servicing (SOOSS), which can correct the malfunctions of deployable appendages of satellites on-orbit by a on-board robot system. In order to verify this concept, a ground testbed has been presented; a robot system composed of a 4-d.o.f. manipulator and an end-effector mounted on the satellite are designed to accomplish the above operations. The main features of the robot system are mechatronics, multi-sensors and intelligent control. The structure of the modular joint is introduced in detail. The multi-finger dexterous HIT/DLR Hand is employed as the end-effector. In the SOOSS, the robot system is controlled through remote teleoperation. The virtual environment of the SOOSS has been built and experiments have been carried out to verify the feasibility of the SOOSS.

Hu, Jia-Sheng; Tsai, Mi-Ching

doi: 10.1163/156855308X292600pmid: N/A

This paper investigates robust fault diagnosis strategies for the auto-balancing of an ergonomically designed two-wheeled cart which is inherently unstable and has a non-minimum phase. To endow the rider with robust stabilization, the normalized coprime factorization for steering is employed for allowing maximum model uncertainties and the driving orientation is achieved with an electronic differential steering control. A model-based fault-detection filter is designed to detect sensor faults. The observer gain obtained by solving an algebraic Riccati equation in the normalized coprime factorization approach offers some design convenience associated with the fault diagnosis filter. In order to promptly alert the rider for safety purposes in the event of a malfunction, the decision-making process to identify a critical failure is also investigated. Finally, evaluation examples are given to illustrate the performance of the proposed robust fault diagnosis strategies.

Kwon, Tae-Bum; Song, Jae-Bok

doi: 10.1163/156855308X292619pmid: N/A

A grid map can be efficiently used in navigation, but this type of map requires a large amount of memory in proportion to the size of the environment. As an alternative, a topological map can be used to represent the environment in terms of discrete nodes with edges connecting them. It is usually constructed by Voronoi-like graphs, but in this paper the topological map is built based on the local grid map by using a thinning algorithm. This new approach can easily extract the topological information in real-time and be robustly applicable to the real environment, and this map can be autonomously built by exploration. The position possibility is defined to evaluate the quantitative reliability of the topological map and then a new exploration scheme based on the position possibility is proposed. From the position possibility information, the robot can determine whether or not it needs to visit a specific end node, which node will be the next target and how much of the environment has yet been explored. Various experiments showed that the proposed map-building and exploration methods can accurately build a local topological map in real-time and can guide a robot safely even in a dynamic environment.

Belkhouche, Fethi

doi: 10.1163/156855308X292628pmid: N/A

This paper deals with the problem of autonomous navigation of an unmanned air vehicle towards a moving ship. The ship is moving in the horizontal plane; however, its motion is not a priori known to the air vehicle. The control laws for the flight path angle and the heading angle of the air vehicle are based on the relative kinematics equations between the vehicle and the moving ship. The goal of the control law is to drive the vertical line of sight angle to zero, while the horizontal line of sight angle tracks the heading angle of the ship. This results in a decreasing range in both the horizontal and vertical planes. The kinematics equations under the control law are derived and our results are rigorously proven. Simulation of various scenarios is carried out.