Advanced Robotics

Qiu, Zhe; Ozawa, Ryuta; Ma, Shugen

doi: 10.1080/01691864.2019.1686420pmid: N/A

A collision detection approach for torque-controlled manipulators is proposed to detect and isolate a collision in an unknown environment without using external sensors. A set of artificial indexes physically representing instantaneous powers are introduced. A contact link can be detected and isolated by finding the smallest power index based on full knowledge of the link parameters. However, it is difficult to precisely obtain the link parameters. Therefore, we propose a robust way in which the collision detection and isolation processes are separated. A collision can be detected by comparing a power-based index with a unique threshold, and a contact link can be isolated by comparing power indexes without any additional threshold. The statistical simulation results using a 6 degree of freedom (DOF) spatial manipulator show the performance of the proposed approach in an ideal situation. Furthermore, the statistical experimental results using the 2- and 3-DOF planar manipulators validate the robustness of the proposed approach.

Li, Jinghui; Ito, Akitoshi; Yaguchi, Hiroyuki; Maeda, Yusuke

doi: 10.1080/01691864.2019.1689166pmid: N/A

Recently, the demand for more accurate, productive, and economical robot manipulators is increasing in the robotics industry. However, a manipulator will produce kinematic errors during production. Thus low-cost kinematic calibration is demanded. Moreover, environmental mapping is also demanded to plan the motions of the manipulator. In this paper, we proposed a simultaneous kinematic calibration, localization, and mapping (SKCLAM) method, which can simultaneously calibrate the kinematic parameters of an industrial robot manipulator using a commercial RGB-D camera attached to its end effector to reconstruct its surroundings. In our method, the kinematic calibration is achieved with feature detection and epipolor geometry. Synthetic and real data experiments were conducted to verify the SKCLAM method. We succeeded in reducing the kinematic errors of the manipulator and reconstructing dense 3D maps of the workspace in the experiments.

Miyake, Shota; Nagahama, Shunsuke; Sugano, Shigeki

doi: 10.1080/01691864.2019.1684363pmid: N/A

High operational continuity in robots requires considerable ongoing manual maintenance, which can be replaced by enabling robots to self-heal. Extensive research on self-healing has been carried out toward the realization of this notion. The introduction of self-healing methods into mechanical systems has been investigated in recent years. However, these studies have been inadequate in terms of usage environment and self-healing efficiency. Therefore, in this work, we developed a self-healing actuator unit that can be applied to conventional mechanical systems by incorporating self-healing ability using a thermoplastic resin inserted at the actuator location. First, thermal simulation was performed to understand the design requirements to reduce healing time and ensure stable self-healing efficiency. Subsequently, experiments were performed with an actual machine, in which self-healing was consecutively carried out four times, resulting in an average self-healing efficiency of 110% and a maximum self-healing efficiency of 115%. These results show that it is possible to carry out healing without any reduction in the fracture strength of the healing mechanism, depending on the healing conditions and the designs of the parts in contact with the thermoplastic resin.

Takeda, Mizuki; Hirata, Yasuhisa; Weng, Yueh-Hsuan; Katayama, Takahiro; Mizuta, Yasuhide; Koujina, Atsushi

doi: 10.1080/01691864.2019.1689168pmid: N/A

Although the development of robot-based support systems for elderly people has become more popular, it is difficult for humans to understand the actions, plans, and behavior of autonomous robots and the reasons behind them, particularly when the robots include learning algorithms. Learning-based autonomous systems which are called AI are treated as an inherently untrustworthy ‘black box,’ because machine learning or deep learning algorithms are difficult for humans to understand. Robot systems such as assistive robots, which work closely with humans, however, should be trusted. Systems should therefore achieve accountability for all stakeholders. However, most research in this field has focused on particular systems and situations, and no general design architecture exists. In this study, we propose a new design method, focused on accountability and transparency, for learning-based robot systems. Describing the entire system is a necessary first step, and transcribing the described system for each stakeholder based on several principles is effective for achieving accountability. The method improves transparency for systems, including learning algorithms. A standing assistive robot is used as an example of the entire system to clarify which system parts require greater transparency. This study adopted the Systems Modeling Language (SysML) to describe the system and the described system is used for the information representation. Information should be represented considering the relationships between stakeholders, information, and the system interface. Because of their complexity, it is difficult for humans to understand the complete set of information available in robot systems. Systems should therefore present only the information required, depending on the situation. The stakeholder–interface relationship is also important because it is more beneficial for professionals to view information relevant to their specialized field, which would be difficult for others to understand. By contrast, the interface should be intuitive for general users. Visualization and sound are very useful means of transmitting information, with advantages and disadvantages for different circumstances. These relationships are important for achieving accountability. Finally, we show an example of implementation with a developed support system. It is confirmed that accountable systems can be designed based on the proposed design architecture.