Abstract: Apparatus and method for controlling at least one hydraulic cylinder by the hydraulic fluid discharged by a hydraulic pump through a control valve. The hydraulic control system includes sensors to sense the conditions of the system and produce responsive signals. In the first stage, a controller determines an initial pump displacement output value and an initial spool displacement output value as a function of the system condition signals according to a plurality of feedback linearization control laws. In the second stage, a second controller produces an output signal for the hydraulic pump and an output signal for the control valve as a function of the initial pump displacement output value, the initial spool displacement value and an input command signal according to linear control laws.

Abstract: An apparatus for indicating efficiency losses in a pump is provided. The apparatus includes a temperature sensor located at the pump input, a second temperature sensor located at a second location, a fluid flow sensor located at the second location, a processor for producing a difference signal in response to signals from the first and second temperature sensors and for quantifying efficiency losses of the pump in response to the difference signal and a signal from the fluid flow sensor. A fault indicator is also provided that is responsive to the efficiency losses.

Abstract: An apparatus is provided for detecting wear in a pump. The apparatus includes a case drain connected to the pump case, a flow sensor for producing signals indicative of case drain flow, a processor for determining whether pump wear has exceeded a predetermined level and for indicating a fault in response to the pump wear exceeding the predetermined level.

Abstract: Apparatus and method for automatically controlling the position of an earthmoving implement of an earthmoving machine in response to varying ground profiles.

Abstract: A control system is provided for a hydraulic circuit having first and second hydraulic valves, a valve spool position sensor, and first and second input devices for producing first and second operation signals. A controller receives a signal from the valve spool position sensor and the second operation signal and responsively modifies the value of the second operation signal in response to the valve spool position signal.

Abstract: Apparatus and method for controlling at least one hydraulic actuator by the hydraulic fluid discharged by a variable displacement hydraulic pump through a closed-center valve and a separate bypass valve. The apparatus receives a mode signal and a stroke signal and responsively controls the output of the variable flow hydraulic pump with either velocity or force modulation control.

Abstract: In one aspect of the present invention, an automatic control system for loading a bucket of a wheel loader is disclosed. The system includes a pressure sensor that produces pressure signals in response to the hydraulic pressures associated with one of the lift and tilt cylinders. A microprocessor receives the pressure signals, compares at least one of the pressure signals to a predetermined one of a plurality of pressure setpoints, and produces lift and tilt command signals in response to the pressure comparisons. Finally, an electrohydraulic system receives the lift command signals and controllably extends the lift cylinder to raise the bucket through the material, and receives the tilt command signals and controllably extends the tilt cylinder to tilt the bucket to capture the material.

Abstract: An apparatus is provided for controlling a machine having a rotatable body and includes a light signal source, a sensor connected to the rotatable body for producing electrical signals in response to receiving the light signal, and a device controlling the rotational speed of the rotatable body in response the electrical signals.

Abstract: A hydraulic system for a construction machine includes a pump for delivering fluid under pressure from a fluid reservoir to at least first and second main valves. First and second input devices are included for producing first and second control signals that are indicative of a desired operation of the hydraulic system. A controller responsive to at least the first and second control signals is provided and produces a compensating signal in response to the first and second control signals. The second main valve is operated in response to both the second control signal and the compensating signal.

Abstract: When compiling machine performance data it is advantageous for such data to have been acquired during periods in which the machine was in the same general operating state. The subject invention provides a system for producing historical data regarding machine operating parameters and including a plurality of sensors for producing signals indicative of the level of machine parameters. A control is included for selecting data representative of a first operating parameter in response to a dependency definition being satisfied and for processing the selected data to provide an indication of machine performance.

Abstract: A control system for automatically controlling a work implement of an excavating machine through a machine work cycle is disclosed. The work implement includes a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder. A position sensor produces respective position signals in response to the respective position of the boom, stick and bucket. A pressure sensor produces respective pressure signals in response to the associated hydraulic pressures associated with the boom, stick, and bucket hydraulic cylinders. A microprocessor receives the position and pressure signals, and produces a command signal. An electrohydraulic system receives the command signal and controllably actuates predetermined ones of the hydraulic cylinders to perform the work cycle.

Abstract: Systems for monitoring sensed parameters and diagnosing fault conditions are useful in many applications. Advantageously, such systems are capable of operating in a plurality of operating modes and in connection with each of a plurality of machines. In the subject invention, a plurality of gauges are included for indicating the levels of the sensed parameters. A plurality of symbols are included for identifying sensed parameters. A control receives an identification code and selectively illuminates one or more of a plurality of gauges and symbols in response to the identification code. A plurality of warning lights are each associated with a switch-type input. A display selectively indicates a pin code for each switch-type input having a fault condition. The indicator lights having an associated switch-type input in the fault condition are flashed. A device selectively indicates a pin code in response to each diagnosable input having a present or a previous fault condition.