TOKYO -- Sony is finally producing enough of its pet robot dog, the Aibo, to meet demand after months selling the coveted toy only through a lottery.

When Sony announced last November that it would roll out the Aibo, the successor to the first version that was terminated in 2006, so many fans flocked to the advance order website that it slowed down. Demand overwhelmed supply after the release in January, and the artificial intelligence-equipped device was sold only to a lucky few.

The company started taking orders in July, but buyers still must wait a month or two for delivery.

Sony, which has not disclosed its Aibo output capacity, shipped 20,000 of the robotic dogs from the January release to July, which suggests that it could turn out 3,000 to 4,000 units a month. It apparently has increased output without upgrading assembly lines or facilities.

In the early months, too many Aibos failed quality screening and had to be repaired before shipment.

Aibos, which are manufactured at a factory in Kota, Aichi Prefecture, in central Japan, undergo a series of inspections. Each one is then packed in packaging that resembles -- and Sony calls -- a cocoon. Aibos that fail repeated testing are put aside for repairs. At first, several dozen defective Aibos were lined up waiting for repairs.

Today, the number is 10 or under.

"We were happy that people wanted it," said a design chief who oversaw mass production. "But we also felt pressured because we were unable to deliver it." 

Normally, problems with an electronic product are resolved during the prototype phase. But with the Aibo, a team of several dozen kept discussing improvements until spring -- after mass production began. They worked off of an Excel spreadsheet that listed hundreds of matters to be addressed.

To decrease the defect rate, the team worked on decreasing human errors.

When the Aibo went into full production, many veteran workers at the Kota plant -- which assembles replacement lenses for single-lens reflex cameras and is known for its technological prowess -- were brought in. But some aibos were mislabeled as defective, said a Sony representative.

The workers made their own tools used for assembly on their own and eliminated many processes prone to mistakes. One component that was difficult to assemble was changed even after release.

Production processes were also reviewed. When multiple workers lubricated 26 parts of the robot, including joints, with brushes, lubricant often leaked onto the surface of the frame. Later, a single worker took over applying the entire lubrication job. In a test of the Aibo's walking, cameras and programs were added so three could be tested at once.

Sony started ramping up output in early May. New workers were trained for a month rather than the usual period of about a week. Changes made to stabilize quality also eased the job for workers, and "this also helped to increase output," the plant's design chief said.