AN IMPROVED FLEXIBLE PNEUMATIC JOINT FOR HORTICULTURAL ROBOTS

A previously reported novel rotary pneumatic actuator incorporating flexible inflatable elements has been improved. The attractions of this patented actuator (registered trade name ''Flexator'') for horticulatural applications lie in its low cost and robust construction. Work to improve its overall performance is described. This involved investigating and minimising sources of hysteresis, increasing torque-to-weight ratio and implementation of control techniques for dynamic positioning. Two joints incorporating these principles have been constructed and linked to form a two-degree-of-freedom manipulator. Each link is 0.4 m long, has a 120-degrees working stroke and moves in the horizontal plane. The manipulator, which weights 8.5 kg, was tested with a 1.5 kg payload, which it positioned to within +/- 2 mm in less than 1.5 s. It is concluded that the performance is adequate for the manipulator to demonstrate a simple horticultural fresh produce packaging application. This will form part of a programme of future work.