An Earthbound Sojourner Rahco Robotic Vehicle Guided By Same Technology As Mars Probe

While Sojourner mugs for the cameras on Mars with rocks named Barnacle Bill and Yogi, a big brother awaits its own mission back here on Earth.

At East Magnesium Road in North Spokane, specifically.

Versions of the sophisticated navigational gear aboard the Mars rover are built into an autonomous self-guided ground transport vehicle developed by Rahco International, said Chief Electrical Engineer Ray Daigh.

He said operators can preprogram a route for the Rahco vehicle - “SGTV” to insiders - and the caterpillar-tracked machine strays no more than six inches from its appointed rounds.

The SGTV moves with the aid of a global-positioning system, the same one that tells lost motorists how to get back on track.

Sojourner, Daigh noted, does not have any orbiting satellites to help it navigate. Instead, the rover must depend on programming transmitted by engineers at Mission Control and a reference point provided by Pathfinder, its base.

Sojourner, capable of maneuvering within millimeters of Martian rocks, clearly incorporates guidance systems more sensitive than the SGTV’s, Daigh said.

But if SGTV lacks some of Sojourner’s precision, it has the advantage of backup systems that allow operators to control the machine using one of two robotic systems. One overrides the vehicle’s collision-avoidance system; the other does not.

A television camera shows what lies ahead, and the SGTV also has a battery of ultrasonic sensors at either end that detect obstructions. Depending on how far away an object lies, the vehicle will slow down or stop to avoid trouble.

Sometimes, it doesn’t take much.

“High weeds. The collision-avoidance system sees them,” Daigh said as he strode off across Rahco’s vast backyard to restart his 40-ton “toy.”

The SGTV is hardly a plaything.

Rahco and its subcontractors - one of which built the Space Shuttle’s arm - was awarded the bid to create the vehicle in March 1995. The U.S. Department of Energy was looking for a system that could retrieve low-level nuclear waste without exposing people to the material.

All dust had to be contained while the waste was picked up, transported and deposited at a processing center.

Rahco designed an excavator that could be operated remotely. Detachable buckets carried empty on the front end of the SGTV are picked up by the excavator, filled, then placed in a lid-enclosed casket on the back of the SGTV, which totes them away to the processor.

Tom Crocker, Rahco’s director of environmental programs, said they turned to satellite positioning because systems based on laser, microwave and other technologies did not give operators the ability to control the system as accurately as needed, considering the sensitivity of materials it handles.

“You want to be accurate to within more than a couple of feet,” he said.

The company had already used satellite positioning to keep salt harvesters in Wyoming within one inch of the required path.

Other systems control huge mining machines in Chile.

The SGTV was successfully tested at the Idaho National Engineering Laboratory in 1995, Daigh said.

Rahco Marketing Director Martin Col said the Department of Energy has not decided whether to use a retrieval system based on a device like the SGTV or one that simply tries to improve containment of the waste where it already sits.

Rahco, with extensive experience in canal construction, could manage the containment if that were the chosen solution, he said.

Meanwhile, Daigh said there are many uses for the SGTV beyond handling nuclear or other forms of hazardous waste.

The sturdy machine could dispose of unstable military ordinance, he said. And with the appropriate attachments, the SGTV could do precision sweeps of abandoned minefields, where the devices still maim and kill thousands.

Mining itself also holds promise. Fitted with a laser guidance system because satellite-positioning is impossible, the SGTV could work underground in conditions unsuitable for people, Daigh said.

He is confident the machine is the answer for somebody’s need.

“This is as close to state of the art in autonomous land-based vehicles as you’ll find,” Daigh said.

, DataTimes ILLUSTRATION: Photo