Anti-pump-slip algorithm for hydraulic steering system

Abstract

A steering system for a vehicle includes a hydraulic steering system configured to, in response to a steering input provided at a steering mechanism of the vehicle, control a pump to control a steering device to steer the vehicle, a sensor configured to sense an angle or position associated with the steering input provided at the steering mechanism, an electric power steering system configured to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump, and a controller configured to determine the pump-slip offset. The pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.

What is claimed is: 
     
         1 . A steering system for a vehicle, comprising:
 a hydraulic steering system configured to, in response to a steering input provided at a steering mechanism of the vehicle, control a pump to control a steering device to steer the vehicle;   a sensor configured to sense an angle or position associated with the steering input provided at the steering mechanism;   an electric power steering system configured to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and   a controller configured to determine the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.   
     
     
         2 . The steering system of  claim 1 , wherein the vehicle is a marine vessel and the steering device is a rudder. 
     
     
         3 . The steering system of  claim 1 , wherein the vehicle is a road vehicle and the steering device is associated with roadwheels of the vehicle. 
     
     
         4 . The steering system of  claim 1 , wherein the controller is configured to determine the pump-slip based on a slip gain factor. 
     
     
         5 . The steering system of  claim 4 , wherein the controller is configured to calculate the slip gain factor based on vehicle speed and a torque associated with the steering mechanism. 
     
     
         6 . The steering system of  claim 4 , wherein the controller is configured to determine the pump-slip further based on a vehicle direction. 
     
     
         7 . The steering system of  claim 4 , wherein the controller is configured to determine the pump-slip in accordance with Slip i =Slip i-1 −(Slip i-1 *[1−Slip_Gain])+(HwAg*Slip_Gain), and wherein Slip i  is a current pump-slip value, Slip i-1  is a previous previously calculated pump-slip value, Slip_Gain is the slip gain factor, and HwAg is a handwheel angle sensor measurement. 
     
     
         8 . The steering system of  claim 1 , wherein the controller is configured to calculate the pump-slip further based on a vehicle direction. 
     
     
         9 . The steering system of  claim 8 , wherein the controller is configured to calculate the pump-slip based on a determination that the vehicle direction is within a predetermined range for a predetermined amount of time. 
     
     
         10 . A method for operating a steering system of a vehicle, comprising:
 using a hydraulic steering system, controlling, in response to a steering input provided at a steering mechanism of the vehicle, a pump to control a steering device to steer the vehicle;   sensing, at a sensor, an angle or position associated with the steering input provided at the steering mechanism;   receiving, at an electric power steering system, a signal from the sensor and providing powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and   determining the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.   
     
     
         11 . The method of  claim 10 , wherein the vehicle is a marine vessel and the steering device is a rudder. 
     
     
         12 . The method of  claim 10 , wherein the vehicle is a road vehicle and the steering device is associated with roadwheels of the vehicle. 
     
     
         13 . The method of  claim 10 , further comprising determining the pump-slip based on a slip gain factor. 
     
     
         14 . The steering system of  claim 13 , further comprising calculating the slip gain factor based on vehicle speed and a torque associated with the steering mechanism. 
     
     
         15 . The steering system of  claim 13 , further comprising determining the pump-slip further based on a vehicle direction. 
     
     
         16 . The steering system of  claim 13 , further comprising determining the pump-slip in accordance with Slip i =Slip i-1 −(Slip i-1 *[1−Slip_Gain])+(HwAg*Slip_Gain), and wherein Slip i  is a current pump-slip value, Slip i-1  is a previous previously calculated pump-slip value, Slip_Gain is the slip gain factor, and HwAg is a handwheel angle sensor measurement. 
     
     
         17 . The steering system of  claim 10 , further comprising calculating the pump-slip further based on a vehicle direction. 
     
     
         18 . The method of  claim 17 , further comprising calculating the pump-slip based on a determination that the vehicle direction is within a predetermined range for a predetermined amount of time. 
     
     
         19 . A processing device configured to execute one or more instructions stored in memory, wherein executing the one or more instructions causes the processing device to:
 control a hydraulic steering system configured to, in response to a steering input provided at a handwheel of a vehicle, control a pump to control a steering device to steer the vehicle;   receive, from a sensor, an angle or position associated with the steering input provided at the handwheel;   control an electric power steering system to receive a signal from the sensor and provide powered steering assistance to the hydraulic steering system based on the signal and a pump-slip offset associated with the pump; and   determine the pump-slip offset, wherein the pump-slip offset corresponds to a difference between the angle or position associated with the steering input and an actual position of the steering device achieved by the pump.   
     
     
         20 . The processing device of  claim 19 , wherein the vehicle is a marine vessel and the steering device is a rudder.