Harvesting in action: the working robotic harvester. Picture: Plymouth University


The potential for robotic harvesters to solve the shortage of EU migrant workers in the horticulture sector has been seized by a Plymouth research group.

Dr Martin Stoelen, Robotics Professor at Plymouth University, is currently developing an agricultural robot with sensors for cauliflower, tomato and raspberry picking. 

They are being developed by the Automatic Brassica Harvest Project (ABC) and will consist of a small platform with wheels or trucks.

The machine’s sensor systems use cameras and create 3D models of the fruit, in order to selectively harvest crops from bushes or hedgerows.

Its tactile sensors squeeze the crop for ripeness and place it into a punnet.

This means the robots will detect bruising and choose what is ripe for picking, based on the shape, size and mass analysed. Its ‘delicate’ handling could help curb the increasing numbers of rotten fruit and vegetables caused from the shortage of migrant workers, noted by the NFU.

Stoelen said: “There are less people who want to go into the field and pick things for a living. When you go out and speak to farmers and producers, they will already say it’s hard to get enough people in. Brexit isn’t going to help and I think they are aware of that”.

He emphasised how the technology could boost productivity in the agricultural sector where it is most needed, with Riviera Produce of Cornwall partnering with the project. 400 out of the current 450 staff at the harvesting production company are from Poland, Bulgaria or Romania.

The robots autonomy and ability to use artificial light at night means they could assess the foods maturity efficiently.

For Stoelen, this would allow them to run three times longer than a person and combined with the slow speed, they could reach a comparable performance to humans.

This is particularly interesting after the BBC’s ‘Inside Out’ program put five young people into Cornish fields to test the difficulty of harvesting labour. The majority said they wouldn’t consider a career in cauliflower picking after a day’s shift because of cold weather conditions and physicality of the task.

For this reason, Stoelen emphasised ‘there is no need for scare-mongering’ surrounding robotics.

He said: “The robots are just tools that enable us to do more than we did before”.


Farmers of the future: Stoelen’s robotic harvester put to practice in the cauliflower field. Picture: Plymouth University

This robotic incorporation into horticulture would allow us to become ‘smarter’ about how we run things in agriculture, with a shift away from industrial, agricultural thinking.

They would act as a ‘service’, working alongside people harmoniously with ‘robot arms’ and machine learning algorithms, rather than a mechanical system.


“It has taken inspiration from biology like so many biological systems which have been adapted to work in the complex environment we live in.

The robots will be safe around people and will be able to reach inside the raspberry bush and won’t break it”.

Similarly, Patrick Aubrey-Fletcher, County Advisor for the NFU, claimed most Cornish people employed by growers have ‘lasted no more than a few days’.

“Labour is hard”.

Perhaps this is why technologies have become more integrated into the UK’s Industrial Strategy for food production and processing.

“Automation is static and requires no permit.

This is why the Government is keen”.

He suggests the politics surrounding EU migration for seasonal work is an influence on the Government’s support of AI harvesting.

Stoelen adds: “Technology is at a mature level, we couldn’t do it five years ago”.

Part of this is the development of sensory data, although it means the robot will be sensitive to difficult weather conditions like rain or fog. Stoelen told Truthfal how this technology will ‘require a focused effort’ by many to make it work, so he does not want to promise too much.

The programming requires ‘complex operations’ because there is a large historical record of commercial industries relying on industrial robots until now. These robots have been put in closed cells in order to ‘more about freely’, which means new initiatives into developing human-friendly bots need time.

The NFU’s lobbying of Government to re-enact the Seasonal Agricultural Workers Scheme (SAW) reveals how these automated harvesters are perhaps not the solution to shortfalls in harvester numbers. The Union ‘welcomes’ the initiative but ‘needs labour in the meantime’.

This SAW scheme which gives EU migrants a permit for seasonal work, was dropped in 2014-2015 because of the mass migration of Europeans. Without the Home Office responding, ‘businesses will suffer, crops will be wasted and supermarkets will look overseas for supply’.

The NFU have been looking at Commonwealth countries, like Canada or New Zealand to help UK harvesting.