Milling machine having a valve current based height measurement system

A method of determining a height of a frame of a milling machine relative to a ground surface, the frame being supported by a plurality of tracks connected to the frame by a plurality of actuators, a tank configured to store hydraulic fluid, each actuator being connected to the tank via a fluid conduit, a control valve disposed in the fluid conduit, and a controller, the method comprising:

• operating the milling machine by raising or lowering the frame relative to at least one track from among the plurality of tracks;
• determining an amount of current flowing through the control valve associated with at least one actuator from among the plurality of actuators;
• determining, using the controller, a flow rate of the hydraulic fluid through the control valve;
• and
• determining, using the controller, the height of the frame relative to the tracks based on the flow rate.

A milling machine, comprising:

• a frame;
• a left front track disposed adjacent a front end of the frame;
• a right front track disposed adjacent the front end and spaced apart from the left front track;
• at least one rear track disposed adjacent a rear end of the frame;
• a milling drum connected to the frame and disposed between the front end and the rear end;
• an engine configured to rotate the milling drum and propel the left front track, the right front track, and the at least one rear track in a forward or rearward direction;
• height adjustable leg columns connecting the frame to the left front track, the right front track, and the at least one rear track, each of the leg columns including:
• an upper section connected to the frame;
• a lower section slidably movable relative to the upper section and connected to one track of the left front track, the right front track, and the at least one rear track;
• and
• a height adjustable actuator connected at one end to the frame and at an opposite end to the one track;
• a tank configured to store hydraulic fluid;
• a fluid conduit connecting the tank to the actuator;
• a control valve configured to selectively control a flow rate of the hydraulic fluid in the fluid conduit between the tank and the actuator;
• and
• a controller configured to:
• determine an amount of current flowing through the control valve;
• determine the flow rate of the hydraulic fluid in the fluid conduit based on the amount of current;
• and
• determine a height of the frame relative to a ground surface based on the determined flow rate.