November 7, 2015 1:00 pm JST
SoftBank's humanoid robot

Peering inside Pepper

TOMONORI SHINDO, Nikkei Robotics staff writer, and TOMOHISA TAKEI, Nikkei staff writer

TOKYO -- Pepper, SoftBank Group's humanoid robot, was built to get to market on time and work as advertised -- not to be easy to mass-produce. 

     This is what staffers at Nikkei Robotics found when they took the contraption apart. Pepper has a complex internal structure. There are few signs that its creators tried to unitize parts and limit the overall number of components, which would make it easier to churn out big batches of bots.

     Still, many of the engineers who peered into the opened-up Pepper said that for an early model, the design made sense.

What makes it tick

SoftBank released a version of Pepper for general consumers in June. Since then, the Japanese telecommunications company has been offering 1,000 units a month, for about $1,650 a pop. They sell out almost as soon as they become available.

     This is the first time a company has sought to mass-produce a humanoid robot driven by 20 motors, which allow for intricate movements. The internal components are concentrated in the head and the base. The trunk section has quite a few hollow spaces. 

     Pepper's head -- removable by holding it and releasing fasteners at the side of the neck -- contains devices that correspond to the human brain, eyes, ears and mouth, though not necessarily in the same places.

     Attached to a cover at the top are touch sensors and four microphones. The robot hears human voices and ambient noise at the top of its head and produces sounds through speakers where a person's ears would be.

     The computer that functions as the brain consists of two circuit boards, one on top of the other, placed aslant at the rear of the head. It features an Intel Atom microprocessor, which offers similar performance to the processors found in tablets. There is also a communications module for wireless networking. 

     Pepper, you could say, is a hothead. The makers seem to have wrestled with ways to dissipate heat from the computer, as well as the 3-D cameras installed in the eye sockets. The cameras, from Taiwan's Asustek Computer, are freely available on the market.

     Two fans inside the head draw air in and expel heat. Metal parts, also used to keep heat in check, consist of two separate pieces, suggesting improvised construction. 

     The designers likely opted to install the computer, sensors and other electronic devices in the head to make it easy to upgrade the semiconductors and other components as technology improves. In fact, SoftBank used a higher-performance microprocessor for the Pepper it released to general consumers, compared with the model offered to developers in September 2014.

Inner emptiness 

Moving down, Pepper's chest contains the motors that move the neck and shoulders; circuit boards that control the motors; more fans for cooling; and circuitry for distributing electric power. Of three fans found behind a back cover, the one under the neck is particularly large, an indication of the neck motor's high load.

     The 10- and 20-watt motors that drive the neck, shoulders and elbows are made by Minebea, a Japanese electronic parts maker. The choice of motors suggests Pepper is not designed to hold heavy objects. The motors that twist Pepper's wrists and clench its fists are from Portescap, a U.S. manufacturer. 

     Hollow spaces in the torso probably resulted from designers' efforts to minimize weight while making Pepper resemble the human form. With a light upper body, a robot is less likely to topple over.

     The base, which resembles legs bonded together, contains heavier components.

     Pepper rolls around on three ball-shaped wheels positioned in a triangle, enabling movement in all directions. These wheels are driven by more powerful motors, made by maxon motor of Switzerland. Positioned between the wheels is the battery, supplied by Germany's Varta Microbattery. On a full charge, it can keep the robot going for 12 hours. The battery tips the scales at 4.7kg, about 16% of Pepper's 29kg weight.

     The base also contains numerous sensors for avoiding obstacles. Six laser elements emit beams around the robot. Three image sensors capture beams that are reflected, indicating an obstacle. Sensors that use ultrasonic waves to measure the distance to objects are found in the front and rear of the base.

     SoftBank Robotics seems unconcerned about Pepper's complexity for now. "At present, mass production is not the top priority," said Kenichi Yoshida, vice president of business development. He said the company is always looking at ways to "update the inside of Pepper." The plan is to hit reliability and performance targets first, and then work on smoothing the assembly process.

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