The Canadian-built robot, named Dextre, passed all but one of the tests. One of the wrist joint brakes in Dextre's left arm slipped a tiny bit more than engineers wanted, but Canada's acting space station program manager said he wasn't too concerned. The brakes help hold the arm steady.
"In the long term it's not going to affect the operation of Dextre in any significant way," Pierre Jean said.
Astronauts and flight controllers planned to test the brake a couple more times in hopes that it slips less as it gets more worn in, Jean said.
Two astronauts plan to take a spacewalk Monday night to add a tool holster and other accouterments for Dextre. When the robot is fully assembled, it will stand 12 feet and have a mass of 3,400 pounds.
Dextre - short for dexterous and pronounced like Dexter - is designed to assist spacewalking astronauts and possibly someday take over some of the tougher chores, like lugging around big replacement parts.
Two astronauts installed Dextre's two 11-foot arms during an overnight spacewalk that lasted into the wee hours of Sunday.
Dextre has seven joints per arm and can pivot at the waist. Its hands, or grippers, have built-in socket wrenches, cameras and lights. Only one arm is designed to move at a time to keep the robot stable and avoid a two-arm collision. The robot has no face or legs.
Space station astronauts will be able to control Dextre, as will flight controllers on the ground. The robot will be attached at times to the end of the space station arm. It is also able to ride by itself along the space station arm's railway.
NASA had some trouble getting power to Dextre earlier in the mission as it lay in pieces on its transport bed. But plugging the robot in to the space station's mechanical arm gave it the energy needed to keep its joints and electronics from freezing.
Dextre will take power directly from the space station after astronauts finish building and installing it later this week.
Space station commander Peggy Whitson said she was always confident that the experts on the ground would solve Dextre's power problem.
"I'm glad it survived being a little cold for a little while," she said in a televised interview.
A total of five spacewalks are planned for Endeavour's nearly two-week visit to the space station, the most ever performed during a joint shuttle-station flight.
While some of the astronauts prepared for Monday night's outing, other crew members stowed equipment that was brought to the station aboard the storage compartment segment of Japan's Kibo lab. That will pave the way for the shuttle Discovery to deliver the $1 billion lab in May.
Visit NASA's Web Page for the STS-123 Mission for the latest developments, background on mission elements, crewmembers and multimedia.