Position Switching Control Method for Electric Crane Boom Considering Lifting Load During Startup

With the advancement of new energy technologies and the demand for intelligentization, hydraulic cylinders in crane booms are gradually being replaced by electric cylinders. However, electric cylinders may induce an initial retraction phenomenon during the crane startup phase when the electromagnetic torque has not yet matched the lifting load. To address this problem, this paper proposes a load-aware position switching control method for an electric crane boom with an integrated brake mechanism. In the braking phase, a fixed-time convergence controller combined with a radial basis function neural network observer is used to build up the holding torque of the permanent-magnet synchronous motor (PMSM) rapidly under uncertain load torque. After the safety current threshold is satisfied and the brake is released, the control law switches to a feedforward Proportional–Integral (PI) controller for position tracking. The switching threshold is derived from the estimated load torque and the PMSM torque constant, and a hysteresis/dwell-time condition is introduced to avoid chatter near the switching boundary. Simulation and experimental results show that the method effectively reduces the initial retraction of the boom.