Hiroyasu Ikeda

A failure-to-safety "Kyozon" system with simple contact detection and stop capabilities for safe human-autonomous robot coexistence

In this paper, we discuss a method to achieve safe autonomous robot system coexistence (or Kyozon in Japanese). First, we clarify human pain tolerance and point out that a robot working next to an operator should be covered with a soft material. Thus, we propose a concept and a design method of covering a robot with a viscoelastic material to achieve both impact force attenuation and contact sensitivity, keeping within the human pain tolerance limit. We stress the necessity of a simple robot system from the viewpoint of reliability. We provide a method of sensing contact force without any force sensors by monitoring the direct drive motor current and velocity of the robot. Finally, we covered a two-link arm manipulator with the optimum soft covering material, and applied the developed manipulator system to practical coexistence tasks.

A failure-to-safety robot system for human-robot coexistence

In this paper, we discuss a method to achieve a failure-to-safety robot system. First, we point out that there has been little study on human detection through contact sensing and we establish the human pain tolerance for human-oriented design of a safe robot. Secondly, for reliability purposes, we provide a method of sensing contact force by monitoring the direct drive motor current and speed of the robot, without any external sensors. Thirdly, we propose a design method of covering a robot with a viscoelastic material to achieve both impact force attenuation and contact sensitivity, keeping within the human pain tolerance limit. Finally, we covered a two-link arm manipulator with an accordingly designed soft covering material, and demonstrated that the developed manipulator system gives no pain to humans.

The construction of a radar-type safety device to complement human vision in safety prediction

A logic-based safety system to facilitate the safety of the human worker in a human-machine system is constructed. The safety system contains a safety confirmation sensor which issues a work output permission to the machine, which predicts and confirms safety, and which samples safety information. If safety information is not obtained, a safe state is assured by decisions based on energy. The safety system governs the work output of the machine according to the safety information sampled by the sensor and guarantees safety involving entropy increase. Any visual safety confirmation action the human worker takes in order to reach a safety decision cannot satisfy this basic system. A safe work system with the function of generating a prediction space on the machine side is constructed by applying an ultrasonic pulsed radar sensor to automated guided vehicles (AGV).

An Application of Magnetorheological Suspension Seal to Pressure Relief Device

The feasibility of the application of a magnetorheological (MR) suspension to the seat surface seal is examined to completely prevent the leakage of inner fluid at the seat surface of pressure relief devices. The burst pressure of the MR suspension seal (MRSS) formed between fixed magnetic poles is measured and the relationships between the burst pressure and the shape factors of the magnetic pole are clarified. The burst pressure of the MRSS is at least 4.0 MPa. Furthermore, the accuracy and repeatability of the relief operation are evaluated by using a model of pressure-relief device, which applies the MRSS. It is confirmed that the general requirement of the pressure-relief device, that the device has an opening pressure variation of within 3%, can be satisfied by the MRSS from the experimental results.

The Construction of Man-Machine Interface for Remote Control Robot

Of the functions of the man-machine interface of the remote control robot, those functions that are especially related to safety are described in this report. Based on the assumption that the human operator inevitably makes mistakes when issuing commands to the robot, two types of interlocks are proposed for the remote control robot system. The robot system is equipped with a fundamental, main-interlock for safety monitoring on the robot side and with a supplementary, quasi-interlock for exceptional tasks that cannot be covered by the main-interlock. A manipulator system approach is taken to add to the reliability of the quasi-interlock. The quasi-interlock scheme that does not impair the safety of the human operator when he makes mistakes is developed for the pneumatic manipulator that can control the compliant motion over a wide range of conditions.

Safety Control Mechanism for Construction Working Robots Working in Collaboration with Human Workers

The principle of safe working based on the safe confirmation is clarified in order to realize such a robot for construction work that can share the working space with human workers. For this purpose, a monitoring system and an intrinsically safe actuator using sensor are prepared for the constructing robot, and a safety control which can allow safe contact with human workers by integrating such system and actuator is realized.

Flow Characteristics of ERF between Two Parallel-Plate Electrodes.

The purpose of the present study is to examine the flow characteristics of electro-rheological fluids (ERF) between two fixed parallel-plate brass electrodes. First, the microscopic behavior of the ER suspension structure between two fixed parallel-plate brass electrodes for the stationary ERF and flow of the ERF was investigated by flow visualization. Then the unsteady relationship between pressure drop and flow rate of the ERF between two fixed parallel-plates was measured under application of an electric field. Velocity distributions of the ERF were obtained by measuring those of the clusters using an image processing technique. On the other hand, the flow of the ERF between fixed two parallel-plates was solved theoretically using the constitutive equation for a Bingham fluid.