Developing flexible automation for mushroom harvesting (Agaricus bisporus) : innovation report

A framework for analysing crop processes and their suitability to automation was developed in order to address the challenges of labour costs and skills availability that UK growers face. Harvesting was found to be the function of greatest potential labour resource savings. The framework compared those crops with the highest Home Production Marketed value, in terms of target detection, target removal, seasonality and environmental factors. Agaricus bisporus (common mushroom) was the crop that was identified as the best candidate for automation. Therefore a laboratory demonstration of a robot arm was designed and developed and experiments conducted showed that the cycle time to pick and place three mushrooms was 20 seconds (compared to a typical human pick rate of 12 seconds (HDC 1996)). The model could in theory, be operated 24 hours a day, giving a picking strategy advantage over a current single day-shift operation. The pick efficiency rate (i.e. success rate) was found to be 69% and if all biological factors are eliminated (e.g. elimination of air conditioning which dried out compost and fruiting bodies), the results suggest a 92% pick success rate is theoretically feasible using the model within optimum environmental conditions. Additionally, 85% of these mushrooms successfully picked had no bruising damage; this results in an overall 78.2% success rate, or 21.8% scrap rate, compared to a 5-10% scrap rate produced by human pickers (Noble 2004), (Komatsu 2005), (Howard 2007). The performance of the robotic harvester was tested within a simulated commercial environment using a discrete event simulation of a UK farm. Results of experiments conducted to compare the performance of a robotic harvesting operation to the current labour intensive operation show that the system would require between 31 and 34 robot harvesters to replace the current 28 humans. The initial investment cost for the proposed fully automated harvesting and growing system, using an Automated Storage and Retrieval System, for the UK farm was found to be from £3.56-3.71m. The payback period for the replacement of the 28 Flexible Full Time Harvesters currently employed was found to be 8 years. The Internal Rate of Return (IRR) was found to be 4%. If the existing growing sheds and tray transport system at the UK farm was kept in service and just the automated harvesting unit was employed, the payback period reduced to 5.5 years and the IRR was found to be 10.5%. The financial analysis provides unimpressive results; however, limitations of these traditional financial appraisal methods were identified from this work. The nonfinancial benefits provide a more compelling reason to go ahead with the proposed solution as the persistent labour supply and direct labour cost issues are currently forcing the UK growers out of business. This work provides growers with a reliable automated harvesting solution and the ability to determine the suitability of its application within their own operations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo