Skip to main content
Open Access Publications from the University of California

UC Davis

UC Davis Previously Published Works bannerUC Davis

Co-robotic harvest-aid platforms: Real-time control of picker lift heights to maximize harvesting efficiency


Harvest-aid platforms are used in modern orchards to improve manual harvesting efficiency, safety, and ergonomics. Typically, workers stand at pre-set heights on a platform's multi-level deck, and each worker harvests fruits inside a canopy zone that is defined by the lowest and highest reach of the worker's arms. However, fruit distributions are non-uniform, and worker picking speeds vary, thus generating a mismatch between labor demand (incoming fruit rates) and labor supply (fruit picking rates) in each zone; this mismatch limits platform-based harvesting efficiencies. To alleviate this problem, we transformed a conventional harvesting platform into a collaborative robot (co-robot) platform. As the co-robotic platform travels forward, it estimates the incoming fruit distribution using a vision system, it measures each worker's picking speed using instrumented picking bags, and controls the heights of hydraulic lifts that move workers up and down. The model-based control algorithm maximizes the machine's harvesting speed by changing the height at which each worker harvests as a response to incoming fruit load because it matches fruit-picking labor supply and demand. Simulation experiments with pre-recorded fruit distribution data validated the approach and provided efficiency gains under various conditions. Apple-harvesting experiments were also performed in a commercial orchard, where 2307 kg of apples were picked: 1045 kg in variable-height zone harvesting mode, and 1262 kg in fixed zone harvesting mode, with workers at fixed heights that were set by the grower. Variable-height zone harvesting mode throughput was 327.6 kg/h vs. 298.8 kg/h for fixed zone harvesting mode at human-controlled platform moving speed, resulting in an improvement of 9.5%.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View