Saturday, August 6, 2011

Agricultural Robotics, Design Challenges

Introduction:  Here are the two videos that sparked this blog post.

The first is a clip of Willow Garage's PR2 in action.  The first thing that struck me was how slow the PR2's movements were.  Then when I went to Willow Garage's web site and checked on the PR2's spec's and price tag of $400K, it struck me how far away from a practical reality the state of the art in robotics still is. 

The second video was of a demonstration strawberry-harvesting robot in Japan.

Now compare the speed, dexterity and agility of movement of these two examples with this video of strawberry pickers in the field.

If you move your attention past the speaker [1] and focus on to the hand movements of the pickers you will get a good introduction as to how quick a robot is going to have to be to compete with existing hand labor.

Design Challenges:   One of the primary challenges for agricultural robotics is cost.  The cost of labor, to the employer, for a field worker can vary greatly, but for purposes of discussion, let’s just pick a good ballpark value of around $125 a day. Over the course of a 6-7 month season this comes to about $20K. Before a robot harvester/tender can compete with manual labor, its cost-of-ownership must be competitive with the cost-of-labor for the worker it is going to replace.

There are some crops that lend themselves to machine harvesting; rice and cotton are two examples that come to mind. Farming crops such as these has already been mechanized and automated [2] to the point that robotics offers little advantage to the farmer. But there are far more crops that require hand planting, hand cultivation and hand harvesting for which robotics brings many advantages to the table.

Cost: the low cost of field labor sets a very low benchmark for the cost of ownership for any robot harvester/tender.

Quantity: California statewide alone, the number of field workers involved in the hand harvesting of food crops is on the order of 100K, while nationwide, maybe 1M. The potential market for field worker robots is huge.

Together these two facts indicate that what the robotics industry needs now is a Henry Ford, not another Willow Garage.  Looking at specifics. 

Power Source: self-powered. For a number of factors, tethering to an external power source is off the table as an option.

Autonomous Operation: hours to days at a time. There would be no cost savings advantage for a farmer to bring in robotic harvesters if all of the robots required an additional team of high-paid college-educated technicians to shepherd them around.

Locomotion: walker. Again, for a number of factors, wheels or tracks are off the table as options too.

unknown. My personal bet, on the long run, would be hydraulics. But for this to happen will require some kind of new breakthroughs in technology. In the mean time I am staying open to any and all nominations for potential actuator types.

Operation, Service and Maintenance: K.I.S.S. Since the workforce that will be responsible for these jobs in the future will be the same people that now operate, service and maintain the existing farm equipment; i.e., tractors, harvesters and etc. (*see Autonomous Operation above)

Machine Vision: the biggie! The computational requirements for machine control are pocket change in comparison to the computational horsepower required to do machine vision. IMHO this is the key element in turning any kind of service robotics from a bench-top toy into a practical reality.

Future Posts:   In future posts I will be taking up in greater detail, each of the challenges listed above.

[2].  From the point-of-view of robotics, mechanization vs. automation is a distinction without a difference. My personal usage is to reserve the term mechanization when hand labor is replaced with machines. I use the term automation to refer to the case when a machine is made to run without the benefit of human operators.


  1. It seems that Willow Garage has just lowered its price for the PR2 from $400K to $200K.

  2. This seems like a project worth investing specially here in the agricultural business here in California