Takuya Ogure

In order to maintain balance, the motors of an inverted pendulum-style, two-wheeled self-balancing vehicle need to continuously control its wheels. The vehicle is at risk of falling over if any of its motors does not function properly. Some research in this regard has been devoted to gaining redundancy by using more motors geared to a common shaft, but such technique is not effective for a seizing failure. In this paper, we propose a differential redundant mechanism to prevent a seizing failure in such vehicles. This mechanism unifies plural motors using a differential mechanism, and allows redundant motors to operate at different speeds. Therefore, the vehicle can maintain balance even if a motor fails. Furthermore, our mechanism can form a redundant system of two outputs using only three motors. We also propose a controller for this redundant mechanism that does not require changing the control mode when seizing failures occur.

Safety is important to a robot that is used in a way that can impact on the wellbeing of people. However, understanding and managing the safety information of a robot is not a trivial task. The quantity of this information is large, and it is usually stored in text-based formats. These factors mean that maintaining safety information when it changes is error prone, and understanding it requires manually searching through lengthy reports. In this paper, we demonstrate that a robot's safety information can be stored in a model-based format. We use the SafeML modelling language to model the results of a safety analysis performed on a semi-autonomous wheelchair. We then illustrate and discuss the benefits of storing and managing safety information using a model, both to maintainability of the information and to understanding the safety of the robot.

Robots need to be dependable to work closely with humans. Further they must be accountable for the system design and development process. This makes some of the safety related standards such as IEC61508 adopt module based architecture and model driven engineering process. On the other hand, module-based architectures using middlewares are popular in the integration phase, when developing robot systems. To elaborate the behaviors of realtime control modules, IEC61499 function blocks derived from PLC languages is useful. Therefore, in this paper, we combine them and present a development process consisting of system design in SysML, elaboration in function blocks and integration using RTMSafety, which is an implementation of RT-middleware for the use of safety-related systems. We also show an example system for a dual-arm robot intended to work with human workers.

Recent years have seen an increase in demand for robots that work closely with humans, or operate at disaster sites. These robots need to have high dependability. At the same time, the idea of system development based on standards is becoming important especially in the field of embedded systems including robots. IEC61508, which is a standard of functional safety requires the V-model of the engineering process and keeping the documents and programs of each phase consistent. However, this process costs a lot and freedom still remains about the choice of tools to support the development, the way of describing specifications/programs in each phase and so on. This makes consideration of the concrete development process and the tools used there before starting an actual development important. Accordingly, the purpose of this paper is to present a concrete architecture and a development process that is IEC61508 ready. We especially focus on the software aspect and mention related standards as well.

It is believed that from this point forward, there will be a need for industrial robots that work alongside and cooperatively with humans. However, the current development of existing robotics technology is inadequate to ensure the safety of such new industrial robots. Our research proposes a safety-planning technology called coexistence hazard avoidance technology, designed for use with a low-powered human-collaborative industrial robot. We load this technology into a risk-management simulator and verify that by using it, a dynamic planning method for the safe operation of robots can be reasonably undertaken in terms of both theory and calculation.

A direct teaching system emphasizing safety and operability for SP02, an upper-body humanoid that cooperates with a human in a cell-production workspace has been described. The system has a direct teaching device, which enables an operator to teach a multi-D.O.F manipulator at comfortable posture despite large changes in the pose of an end-effector. The double-checked safety-related part (SRP/CS) introducing a safety module satisfies the safety performance defined in the international safety standard. To make the teaching easier to perform, impedance parameters in a variable impedance control are set through several direct teaching experiments. Through a simple direct teaching experiment, the safety performance of the SRP/CS and the teaching performance of the direct teaching system was successfully confirmed.

Although the need for humans and robots to work together in close proximity is increasing, this is currently not allowed with conventional industrial robots for reasons of safety. Next generation robots that can work safely in close proximity with humans must not only be highly functional, but must also be highly reliable with built in safety features. With this aim in mind, we have developed a safety module that integrates safety functions required for robots to work side by side with humans. The safety module is designed to be compliant with international safety standards and Japanese law. Redundant sensory signal processing by an external hardware module and plug-in software installed in the robot controller ensure high-reliability and flexibility. This paper describes the concept and design of the safety module and shows some evaluation results of its safety functions.

Purpose – The purpose of this paper is to clarify the underlying hazards of human-mimic human-collaborative industrial robots. Design/methodology/approach – Preliminary hazard analysis is applied to a new industrial upper-body-humanoid under development. The result of the analysis is summarized by Fishbone diagram analysis. Findings – Six hazard categories involving a four-class physical human robot interaction hazard classification are derived from the analysis. Originality/value – The method of analyzing hazards presented here and the hazard theory derived from the analysis can be used in other developmental projects.