Rivet by rivet, a new generation of hazardous-duty robots is being forged in laboratories to tackle dangerous and dirty tasks often avoided by human workers. Until now, most robots have been put to work in factories, handling mundane chores from welding to spray painting.
But these new mechanical laborers - from deep-sea robots to the snakelike machines that inspect cubbyholes in nuclear plants - are designed to toil outside manufacturing plants in high-risk jobs.
And since a chief thrust behind their development is improved safety instead of increased productivity, little concern has so far surfaced among unions and workers about job displacement.
Instead, the biggest obstacle to moving the robots from lab bench to marketplace is technological - coming up with machines sophisticated and sturdy enough to work in harsh surroundings. Among areas where hard-hat robots may be put to work:
* Mining. Much of the effort here focuses on developing robots for jobs in underground coal mining, where more than 100 fatalities usually occur each year. Researchers at Carnegie-Mellon University (CMU) in Pittsburgh, for example, are working on an ''intelligent'' machine to do roof bolting, one of the more dangerous mining tasks. A prototype may be ready in 18 months. Backed by coal firms and the US Bureau of Mines, CMU scientists are also looking into robots for coal hauling and processing.
The Bureau of Mines will put a slim $100,000 this year into its own basic research on coal-handling robots. At the Massachusetts Institute of Technology, engineers are developing humanlike ''sensing'' systems for robotic excavators, roof-bolters, and haulers. But it will be five years or so before any move beyond the idea shop.
* Nuclear plants. A handful of companies and universities around the world are working on ''snakelike'' robots that will slither through pipes and inspect remote areas of power plants for cracks and other flaws. Japan is expected to put one on the market next year.
In the US, Westinghouse (builder of nearly half the nation's operating nuclear plants) is working on more advanced ''snake'' robots that will have grippers for walking up poles and the capacity to carry out complex tasks. But these machines are probably eight years away, says Westinghouse scientist Harry Andrews.
Simpler robots have long been used in nuclear plant work - but are limited in the tasks they can do. Two were recently enlisted for inspection and radiation testing at Three Mile Island. A third will go to work there by year's end. Fitted with camera and radiation sensors, the small tanklike vehicle, with a robot arm as a turret, will help dispose of radioactive sludge.
* Construction. Carnegie-Mellon researchers are working on a remote-controlled robot to excavate around natural gas lines - dangerous work, in which as many as 150 people a year are killed. The robot would do the digging , then blow away any fumes in the area so workers could move in to repair the leak.
Also being developed at various universities are robots that will lay bricks, install liners inside tunnels, and help build houses. ''This really represents the first efforts to take robots out of the factory,'' says Dwight Sangrey, head of CMU's civil engineering department.
Japan, through a government-backed ''extreme job robot development project,'' is pushing to build robots for construction jobs in particular. The reason, US experts say, is not safety but a need to make up for a labor shortage. Two other areas where remote-controlled machines are joining employment rosters include police work (for bomb disposal) and underwater research.
Still, experts say it will be years before machines replace man in many of these jobs. Today's factory-bound robots perform simple repetitive tasks, usually in a stationary position. The new nonfactory machines have to move about - and maneuver in obstacle-strewn environments. In most cases, this means equipping them with sophisticated sensors and some artificial intelligence. Then, too, using robots in these jobs will undoubtedly lead to some worker displacement. Some unions are already closely watching their development.