System and method for controlling an integrated pump and energy recovery system

Abstract

A system for controlling an integrated pump and energy recovery system is disclosed. The processor-based device is configured to receive a position signal representative of a measured position of a piston assembly movable between a top dead center and a bottom dead center of a hydraulic cylinder and a pumping cylinder, from the position sensor. The processor-based device is also configured to receive a pressure signal representative of a measured pressure of at least one of a fluid medium fed from the pumping cylinder to a filtering device, a hydraulic fluid fed from the hydraulic pump to the hydraulic cylinder, from the pressure sensing unit. The processor-based device is further configured to generate a control signal based on the position signal and the pressure signal, and transmit the control signal to the hydraulic power unit to control measured position of the piston assembly and a pressure of the fluid medium.

1 . A system for controlling an integrated pump and energy recovery system, the system comprising:
 a processor-based device communicatively coupled to a position sensor, a pressure sensing unit, and a hydraulic pump of a hydraulic power unit, wherein the processor-based device is configured to:
 receive a position signal representative of a measured position of a piston assembly movable between a top dead center and a bottom dead center of a hydraulic cylinder and a pumping cylinder, from the position sensor, wherein the hydraulic pump is coupled to the hydraulic cylinder; 
 receive a pressure signal representative of a measured pressure of at least one of a fluid medium fed from the pumping cylinder to a filtering device, a hydraulic fluid fed from the hydraulic pump to the hydraulic cylinder, from the pressure sensing unit; and 
 generate a control signal based on the position signal and the pressure signal, and transmit the control signal to the hydraulic power unit to control the measured position of the piston assembly and a pressure of the fluid medium. 
   
     
     
         2 . The system of  claim 1 , wherein the processor-based device is a proportional-integral-derivative controller. 
     
     
         3 . The system of  claim 1 , wherein the processor-based device is further configured to generate an error position signal by comparing the measured position of the piston assembly with a desired position. 
     
     
         4 . The system of  claim 3 , wherein the control signal is representative of a sum of a scaled velocity feed-forward term and a scaled error position signal of the piston assembly. 
     
     
         5 . The system of  claim 1 , wherein the processor-based device is further configured to generate an error pressure signal by comparing the measured pressure with a desired pressure. 
     
     
         6 . The system of  claim 5 , wherein the processor-based device is further configured to generate an error position signal by comparing the measured position of the piston assembly with a desired position. 
     
     
         7 . The system of  claim 6 , wherein the control signal is representative of a weighted sum of a scaled velocity feed-forward term and a scaled error position signal of the piston assembly and a scaled error pressure signal. 
     
     
         8 . The system of  claim 7 , wherein the weighted sum comprises a weighting factor determined based on the measured position of the piston assembly. 
     
     
         9 . The system of  claim 8 , wherein the weighting factor is a linear weighting factor. 
     
     
         10 . The system of  claim 8 , wherein the weighting factor is a quadratic weighting factor. 
     
     
         11 . The system of  claim 7 , wherein the control signal is further representative of a position control mode for controlling the measured position of the piston assembly when the position of the piston assembly is proximate to the top dead center or the bottom dead center during a piston stroke. 
     
     
         12 . The system of  11 , wherein the control signal is further representative of a pressure control mode for controlling a pressure of the fluid medium during a remaining part of the piston stroke. 
     
     
         13 . The system of  claim 12 , wherein the weighted sum comprises a weighting factor equal to one for the position control mode and equal to zero for the pressure control mode. 
     
     
         14 . The system of  claim 5 , wherein the processor-based device is further configured to generate a first error velocity signal by comparing an estimated velocity of the piston assembly with a target velocity, wherein the control signal is representative of a scaled first error velocity signal and the target velocity is representative of a sum of a design velocity of the piston assembly and the scaled error pressure signal. 
     
     
         15 . The system of  claim 14 , wherein the processor-based device is further configured to generate a second error velocity signal by comparing a design velocity with the estimated velocity of the piston assembly, and adjusting a desired pressure of the fluid medium representative of a scaled second error velocity signal. 
     
     
         16 . A method implemented via a processor-based device for controlling an integrated pump and energy recovery system, the method comprising:
 receiving a position signal representative of a measured position of a piston assembly moving between a top dead center and a bottom dead center of a hydraulic cylinder and a pumping cylinder, from a position sensor, wherein the hydraulic cylinder is coupled to a hydraulic pump of a hydraulic power unit;   receiving a pressure signal representative of a measured pressure of at least one of a fluid medium fed from the pumping cylinder to a filtering device, a hydraulic fluid fed from the hydraulic pump to the hydraulic cylinder, from a pressure sensing unit;   generating a control signal based on the position signal and the pressure signal; and   transmitting the control signal to the hydraulic power unit to control the measured position of the piston assembly and a pressure of the fluid medium.   
     
     
         17 . The method of  claim 16 , further comprising generating an error position signal by comparing the measured position of the piston assembly with a desired position. 
     
     
         18 . The method of  claim 16 , further comprising generating an error pressure signal by comparing the measured pressure with a desired pressure. 
     
     
         19 . The method of  claim 18 , further comprising generating an error position signal by comparing the measured position of the piston assembly with a desired position. 
     
     
         20 . The method of  claim 18 , further comprising generating a first error velocity signal by comparing an estimated velocity of the piston assembly with a target velocity, wherein the control signal is representative of a scaled first error velocity signal and the target velocity is representative of a sum of a design velocity of the piston assembly and the scaled error pressure signal. 
     
     
         21 . The method of  claim 20 , further comprising generating a second error velocity signal by comparing a design velocity with the estimated velocity of the piston assembly, and adjusting a desired pressure of the fluid medium representative of a scaled second error velocity signal. 
     
     
         22 . A non-transitory computer readable medium having instructions to enable a processor-based device to:
 receive a position signal representative of a measured position of a piston assembly moving between a top dead center and a bottom dead center of a hydraulic cylinder and a pumping cylinder, from a position sensor, wherein the hydraulic cylinder is coupled to a hydraulic pump of a hydraulic power unit;   receive a pressure signal representative of a measured pressure of at least one of a fluid medium fed from the pumping cylinder to a filtering device, a hydraulic fluid fed from the hydraulic pump to the hydraulic cylinder, from a pressure sensing unit;   generate a control signal based on the position signal and the pressure signal; and   transmit the control signal to the hydraulic power unit to control the measured position of the piston assembly and a pressure of the fluid medium.