Disclosed are a method and a device for detecting a position of a piston rod, a hydraulic cylinder and a working machine. The method includes: acquiring a target image at a target position; obtaining a pixel information corresponding to the target image; comparing the pixel information with a pixel database of the piston rod, a full-stroke pixel information of the piston rod and a relationship between the full-stroke pixel information of the piston rod and a displacement of the piston rod are stored in the pixel database of the piston rod, and the full-stroke pixel information at least comprises the pixel information within a range in which the piston rod is configured to move relative to the target position; and determining a position information of the piston rod based on a comparison result.

Disclosed here is a system and method to control multiple eversion-based actuators using a single motor, or no motor, thereby reducing the size and cost of the multiple eversion-based actuators. An activation mechanism can include a motor rotating in an expansion direction, rotating shaft, clutch, brake, pressure source under high pressure, and/or valve. The activation mechanism can cause the actuators including a wound reel of material to unwind and lengthen. A retraction mechanism can include a motor rotating in a contraction direction opposite the expansion direction, rotating shaft, clutch, pressure source having low pressure, valve associated with the pressure source, and/or the passive retraction system. The retraction mechanism can cause the actuators to rewind and shorten.

A linear actuating device comprising a main actuator provided with a main body and with a main rod able to move with at least one degree of freedom in translation with respect to the main body. According to the disclosure, the linear actuating device comprises an emergency system configured, in a nominal operating mode of the linear actuating device, to allow the main rod to move with respect to the main body and, in an emergency operating mode of the linear actuating device, to return and then maintain the main rod in a predetermined refuge position.