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Robots Integrating More Closely into Society Power Devices Contributing to Improved Mobility
Major security firm Sohgo Security Services Co., Ltd. of Japan, known as ALSOK, began developing robots to replace human beings in various tasks over thirty years ago, and was one of the first to launch businesses utilizing robots. Takayoshi Tsuchiya, in charge of robotic development at the firm, discussed the future of intelligent robots and their interaction with us, as well as the technologies needed to create them, with Kei Nishioka, Project Manager, Power Module Products at Rohm Co., Ltd. of Japan, who develops the power modules for the motor drive systems essential in robotics.
Nishioka: Why did ALSOK, which provides security services, decide to begin developing robots?
Tsuchiya: Our work into robots began in 1982, and the biggest reason was our need to improve the efficiency of on-site security. We thought that robots could reduce labor requirements, thereby improving efficiency in security applications where labor is highly centralized. We were already concerned about possible future labor shortages due to the rising average age of the population in Japan. The introduction of robots would also reduce security personnel fatigue, and help prevent work-related injuries.
Nishioka: When did it emerge as a business line?
Tsuchiya: The C4 GuardRobo we began selling in 2002 for indoor use was the first. It could propel itself using electric motors and was equipped with a variety of guard functions including sensors for human presence and fire, and image monitoring. It also had a display with touch-panel input, and a voiced information function.
Robots Spread to Science Museums and Other Facilities throughout Japan
Nishioka: That means you've had products in the market for over a decade. What is your product line-up now?
Tsuchiya: The Reborg-Q, which first entered service as a guard robot in 2006, is the latest model (Fig. 1).
As with other models in its series, it comes with a variety of guard functions, and is self-propelled using wheels and electric motors. The power system includes both rechargeable and lead-acid storage batteries. The robot patrols a programmed route, transmitting video of the surrounding facility and other information to the security center while patrolling, and then automatically returns to its charging station at the end. Optional units are available to handle various hazardous tasks, such as extinguishing fires.
When we completed the Reborg-Q we received a large number of inquiries from various commercial complexes, science museums, and other facilities searching for newsworthy attractions utilizing advanced technology, so we applied the technology from the Reborg-Q in the An9 series of products that emphasize information provision functionality.
It comes in two types, the An9-PR self-propelled system for commercial complexes and similar applications, and the An9-RR immobile system for company reception desks. All of these robots are in widespread use across Japan, including at Tokyo Tower, the Science Museum in Tokyo, the Otsuka Museum of Art, and Canal City Hakata.
Further Improvements to Sensing Technology Crucial
Nishioka: Robots are gradually spreading into every phase of our lives, and sensing is one technology that is absolutely indispensible in realizing robotic functions. Rohm is applying the semiconductor technology gained through decades of work in the field into the development of diverse sensors, including illumination sensors, proximity sensors, and wide-waveband imagers, as well as providing solutions combining them with communications, power generation, and other applications. These sensors will be useful in implementing new functions for robots.
Yes, sensing is very important in robot development, and there are yet many unresolved problems with sensing technology. For example, laser sensors are used to detect people and obstacles, but they can only detect within the plane. We hope to make three-dimensional detection possible. In combination with facial recognition systems, it should be possible to capture the image of the entire human body.
We also hope to enhance functions for detecting obstacles and people while in motion. When a robot is moving, it can be very difficult to determine if a detected object is still, or is also in motion. Resolving that problem would significantly improve functionality.
Nishioka: Another technology that may contribute to further evolution in robots is the power modules I work with (Fig. 2), which are essential components in motor drive circuits. Lately the development of power semiconductors made with next-gen materials such as silicon carbide (SiC) and gallium nitride (GaN) is accelerating, along with the power modules incorporating them. They offer excellent energy utilization efficiency, and should be able to contribute to smaller, more energy-efficient robot drive systems.
The first SiC power semiconductors are also entering commercial use, such as Schottky barrier diodes, MOSFETs, and power modules. In fact, Rohm was the first Japanese semiconductor manufacturer to volume-produce SiC Schottky barrier diodes, in April 2012. In December that year we were the first company in the world to volume-produce MOSFETs.
Tsuchiya: All of the self-propelled robots we manufacture achieve their mobility through a system combining rechargeable batteries with electric motors. This system makes extensive use of power devices.
When we design our robots, we are extremely concerned with energy efficiency and weight. The Reborg-Q guard robot measures 650 mm x 700 mm x 1300 mm, and weighs 120 kg. It requires considerable weight to ensure stability, so we can't simply design a lightweight model, but if we can avoid any excess weight it contributes to improved mobility.
Nishioka: Conserving energy and making motor drives and other systems smaller and lighter are also issues in electric vehicles (EV) and hybrids. To address this requirement, we developed a compact intelligent power module combining a drive circuit using high-efficiency SiC power devices and various protection circuits. It only takes up about one-tenth the volume of the conventional module. There's nothing else that small on the market that we know of.
These modules make use of newly developed gate driver integrated circuits (IC) with internal isolated devices. We integrated the gate driver ICs and isolated devices into single-package designs, and also adopted a new architecture for the isolated device to slash volume (Fig. 3).
Tsuchiya: Another major problem with robot mobility is batteries. We use lead-acid storage batteries in our commercial robots now, but they are very heavy. We would like to use small, lightweight batteries, but only heavy lead-acid storage batteries can provide the power needed to keep the self-propulsion system and internal electrical circuits operating for long periods of time. The problem can only be fundamentally solved by improving the battery itself, but we also need to improve the performance of the battery management system that minimizes overall power consumption and maximizes battery performance. If the per-charge operating time can be extended it will significantly improve robot convenience.
Intimately Linked to Social Change
Nishioka: Along with the problems of size and weight, this is another major issue that affects both EVs and hybrids. Rohm recognized this, and was the first firm to develop a range of chips for battery management systems, including for charging units, to help resolve it.
Power devices are needed in an increasing variety of applications, and must address a rapidly diversifying variety of application requirements. It is becoming especially difficult to fully meet market requirements for power modules, which integrate multiple devices. To better address this need, Rohm recently strengthened its power module division by creating a new group specifically for power module development that extends laterally through the research, product development, manufacturing, and quality assurance divisions There is considerable demand for power modules in various social systems, too, and market requirements for social applications cover a much broader scope than our prior products. This broader scope made it very difficult for our former divisions to fulfill all those requirements adequately, which is why we created this new organization to bring together all the expertise and experience of the company. I think this type of lateral organization will become more and more important in the future as technology begins to directly deal with various social applications.