Balanced lifting device, vehicle-mounted exchange box system and multi-oil cylinder synchronization method

A multi-oil cylinder synchronization method, comprising following steps:

• obtaining desired motion trajectory parameter values X, Y and Z of two lifting arms:
• the motion trajectory parameter values comprise a desired telescopic length value Z of a first drive device, a desired telescopic length value Y of a second drive device and a desired telescopic length value X of a third drive device;
• calculating error values Δs between the two lifting arms at the current moment:
• obtaining AD values Δad read by displacement sensors corresponding to the first drive device, the second drive device and the third drive device at the current moment;
• calculating telescopic length values S of the first drive device, the second drive device and the third drive device in the two lifting arms respectively at the current moment according to the obtained values Δad;
• calculating telescopic length error values Δs between the first drive device, the second drive device and the third drive device in the two lifting arms at the current moment respectively according to the obtained telescopic length value S;
• calculating difference values e(t):
• calculating the difference values e(t) between the telescopic length values S of the first drive device, the second drive device and the third drive device at the current moment and the desired telescopic length values X, Y and Z of the first drive device, the second drive device and the third drive device respectively according to the obtained X, Y and Z values and the obtained telescopic length values S;
• conducting compensation operation:
• conducting compensation operation by inputting the obtained telescopic length error values Δs and the obtained difference values e(t) into a PID controller to obtain compensation values Δd;
• calculating telescopic lengths S of the corresponding first drive device, second drive device and third drive device according the compensation values Δd obtained from the e(t) of the previous node.