Image of a two-row robotic grape pruner under development by Vision Robotics.

Image of a two-row robotic grape pruner under development by Vision Robotics.

The same company working to develop robotic harvesters for the tree fruit industry is using its know-how to build a two-row mechanical grape pruner that would make selective pruning cuts. A proof-of-concept unit could be in the field for demonstration by 2009.

The robotic grape pruner may be closer to market than related equipment they are developing for the citrus and tree fruit industry, said Derek Morikawa, chief executive officer of Vision Robotics, located in San Diego, California. He hopes to have an industry investment group put together by the end of 2007 to fund the proof-of-concept unit. It would then take about 12 months to build the unit to test in the field. After field testing the unit and making adjustments from field research, a commercial prototype would be developed. The proof-of-concept unit would be a scaled-down version of the commercial unit, pruning only one row instead of two, but would be designed to do everything else.

"I’ve now met with the majority of the large growers and wineries in California, and we’ve gotten very, very good response," he said, adding that they are working to establish a consortium of investors. Morikawa said the group is "very enthusiastic and excited" and will provide input for the pruning styles and criteria to be built into the robotic system. "We’re also looking for a Washington State connection," he added

Precision pruner

The concept is based on a precision pruner supported by a vision system, Morikawa explained. It would be programmed for common pruning styles, such as spur or head pruning and cane pruning, as well as pruning styles based on quality or quantity. A grower would be able to control the style of pruning that he or she desires.

"The pruning will look exactly like the pruning from a highly skilled crew," he said, adding that the pruning shear will prune the vine just as skilled workers do.

How does it work? A pair of similar cameras positioned on each side of the vine scans down the vine taking hundreds of different pictures to catalog diameter and position of the canes. The robot then knows the cane dimensions and angles, sizes and locations of the buds, and more. Pruning rules preprogrammed into the robot would tell it how to prune and what to do when it sees things like upward-facing or broken canes.

"That’s the artificial intelligence part of the robot," Morikawa said, adding that once the machine is programmed with rules, the robot is then making the pruning decisions.

The robot uses the cameras to position itself over the vine rows and also controls the speed. A driver would tow the robotic pruner down the vine row and make turns at the end of the rows.

Industry need

There’s no question that the robotic pruner represents the next phase of mechanization for the wine grape industry, said Nick Dookozlian, research director for California’s E. & J. Gallo Winery. Although the wine grape industry is more mechanized than some commodities, with mechanical harvesters and hedging-type pruners that make non-decision cuts, the industry has gone as far as it can with existing technology, he said.

A robotic pruner is headed down the right path, using artificial intelligence to make decisions, Dookozlian said. "What they are doing is on the right track. But how close are they? I don’t know."

He has watched laboratory demonstrations of Vision Robotics’ grape pruner and believes that the technology exists to put such a concept into the field. "But will it be fast enough and robust enough to be commercially viable?"

A robotic pruner would need speed to operate efficiently and must be durable enough to withstand inclines and uneven terrain, continuous operation, and such.

"But we’ll never know until we try," Dookozlian commented. "If anybody can do it, it would be them."

Birth of idea

Vision Robotics came up with the idea for a robotic grape pruner when it began working with California’s citrus industry to develop a robotic citrus harvester. They met with an agricultural equipment manufacturer in Lodi, California, to discuss agricultural machines. Claude Brown, owner of Agriculture Industries Manufacturing (AIM), which manufactures mechanical grape harvesters, suggested that they should also consider developing a grape pruner.

Morikawa said that Brown showed them around vineyards and pruning equipment and shared his thoughts about the need to make mechanical pruners more selective.

"We said ‘wow.’ This is something we can do with existing technology," Morikawa said. To further explore the concept, they shared a booth with AIM last January at the Unified Wine and Grape Symposium, an annual gathering of thousands of grape industry representatives in Sacramento, California. The robotic pruner concept generated a lot of interest from growers, he added.


In the future, Morikawa envisions an autonomous pruning unit, thereby eliminating the driver. "Our core technology is in building navigating- and driving-type robots," he said. "That’s our specialty.

"A fairly significant cost of a robot is the salary of the person operating the system. The salary can represent 30 to 40 percent of the cost of running the machine," he said.

Morikawa can foresee other benefits and cost savings from having a driverless unit—nighttime pruning and pruning during cold winter temperatures. "Pruning is done during one of the worst times of the year in terms of weather."

But for now, he said that the growers are telling them that they don’t want an autonomous unit to start with.

Down the road, the same basic unit used in grape pruning could lead to robots designed to handle other vineyard tasks, like thinning and harvesting.

Developing pruning technology is the logical next step for their apple industry work, Morikawa noted. Apple pruning of trellised trees is not that much different than grapes on a trellis, he said.