Method and equipment for multi-linkage series push-pull suspending carrying bananas

Fast-ripening banana are often required to be harvested in a timely manner at full maturity in the sustainable industry. However, manual handling after harvesting cannot fully meet the large-scale transportation to central processing points, due to its high cost and low efficiency. The lifting and transport of existing transport carts and drones can also result in delays with the delivery of bunches to processing, packaging, and transshipment points. Delays in manual transportation to the destination have also caused the banana to rot. It is often required to suspend banana bunches during transport. In this study, the push-pull suspension device was developed for banana conveyance using tandem multi-link assemblies. A systematic investigation was made to examine the gradients when transporting banana from the harvest site to the processing plant, and the spatial constraints between banana trees. The space between banana trees was utilized for the support frames and transport tracks. A power unit was used to drive a series of multi-link mechanisms, pushing and pulling them in sequence. Two-link mechanisms were connected via a joint mechanism with banana suspension hooks fixed below the joint. The banana were then suspended from these hooks. The series-connected multi-link mechanism then moved to transport the suspended banana, due to the pushing and pulling action of the drive unit. The driving force and transport speed of the transport device were determined under different gradients, according to the size and weight of the banana bunches, the transport, and the structural parameters of the track. Models were then established to determine stress in the transport track and support structure, as well as the stability of the support. An optimal combination of the parameters was determined as the inclination angle of the track for different bunch weights, support deflection, and reaction forces at various loading times and transport speeds. Additionally, experimental tests were conducted on a multi-link series push-pull transport system for banana suspension. The results show that the maximum transport speed on a 25° gradient track was 1.53 km/h using a 3.30 kW drive unit to power a push-pull banana transport with 30 connecting rods, when carrying 1 350 kg of banana in 30 bunches of 45 kg each. Furthermore, there was a high strength of the track support connection when transporting 30 bunches of banana with a maximum weight of 70 kg per bunch. The inclination angle of the track was less than the critical stability angle for the track and its supports. The transport load on the carrier track was significantly lower than the ultimate load at which the transport track and its supports, indicating the critical nonlinear buckling. Theoretical and experimental results further confirm that the transport speed was a key factor influencing the stability of rail transport. Transporting banana at speeds exceeding 0.58 km/h reduced mechanical damage to bunches. Excessively high speeds also increased mechanical vibrations in the track and its support. Additionally, the maximum vibration acceleration of the transport track was 43.89, 130.92, 43.61, and 165.54 m/s², respectively, at the transport speeds of 0.98, 1.16, 1.49, and 2.21 km/h. This sharp increase in vibration acceleration was attributed to the excitation amplification, whereby the load excitation frequency was close to the natural frequencies of the track and supports. Therefore, the transport speed of the device was adjusted for the load excitation frequency during operation. The natural frequency of the track was then avoided to minimize vibration acceleration for transporting banana in the device.