Abstract: A system and method are disclosed for turning off the voltage to a pump jack electric motor during predetermined periods of time to save energy. In the method, the motor's response to closed-loop control may be evaluated over several pump strokes. The periods of the pump stroke when it is feasible to turn off the motor may be identified. The consistency of the measurements over several strokes may be evaluated. The motor may be turned off during predetermined periods on subsequent pump strokes when each pump stroke shows sufficiently similar behavior to that predicted during the closed-loop control process. The system may return to the closed-loop control process after a predetermined period of time to adjust to any changes in the system.

Abstract: A system and method are provided for reducing the energy consumed by a pump jack electric motor by reducing the supply voltage to the motor when the motor would be generating energy in open loop mode. By substantially eliminating the energy generation mode, the braking action of the utility grid in limiting the acceleration of the motor and system that would otherwise occur is substantially removed. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action.

Abstract: The invention relates to a pump system comprising a positive-displacement pump module, preferably a screw pump, a drive module which can be exchanged separately from the positive-displacement pump module, said drive module comprises an electric drive motor and a frequency converter associated therewith for controlling or adjusting a drive motor speed, control means comprising a controller for producing an adjustment variable (YS) for the frequency converter in accordance with a reference variable (W) and a first actual operational parameter (X) and logistic means associated with the controller, and reference variable defining means for providing the reference variable (W) for the control means. According to the invention, the control means are provided in a control module separately from the drive module, and the drive module can be exchanged separately from the control module, and the drive module does not have a designed and/or controlled controller for producing the adjustment variable (YS).

Abstract: A cyclic adsorption process is provided having pressurization and depressurization steps and driven by one or more centrifugal machines operating under acceleration and deceleration conditions wherein the deceleration rate of the machine is controlled to minimize power consumption and maximize the efficiency of the process. The operating speed of the centrifugal machine during deceleration is matched to the measured ratio pressure conditions so that the centrifugal machine arrives at its minimum operating speed near the point required to begin acceleration.

Abstract: Embodiments of the present invention provide pumps with features to reduce form factor and increase reliability and serviceability. Additionally, embodiments of the present invention provide features for gentle fluid handling characteristics. Embodiments of the present invention can include a pump having a motor driven feed stage pump and a motor driven dispense stage pump. The feed stage motor and the feed stage motor can include various types of motors and the pumps can be rolling diaphragm or other pumps. According to one embodiment, a dispense block defining the pump chambers and various flow passages can be formed out of a single piece of material.

Abstract: A method for transmitting data from a downhole component includes: measuring a borehole fluid pressure by a receiver at a selected sampling rate and estimating a pressure signal transmitted through the fluid based on the sampled fluid pressures; measuring, by at least one pump stroke sensor, operation of a pump configured to advance fluid through the borehole; identifying individual stroke events from the pump stroke sensor measurement; generating a digital pump stroke signal in response to detecting one or more stroke events, each pump stroke signal including a digital time value associated with each of one or more stroke events; and transmitting the pump stroke signal to the receiver.

Abstract: A device controls power supplied from an inverter having a semiconductor switching element to an electric compressor having an external drive source or a built-in motor. The device includes: an apparatus for calculating a starting current value required for starting the compressor from the pressure at the discharge side circuit of the compressor; an apparatus for calculating a permitted current value of the semiconductor switching element from the temperature of the inverter installation portion; and an apparatus for comparing the calculated compressor starting current value to the permitted current value of the semiconductor switching element so as to determine whether to permit a start of the compressor.

Abstract: A displacement pump arrangement, method for operating the displacement pump arrangement and a control device for controlling the displacement pump arrangement provide rotational-speed-variable control of an expeller pump unit for feeding a fluid. The arrangement includes an expeller pump and a drive, the drive being composed of an electric drive motor and a frequency converter, and a control device. The control device controls a state value such as a final pressure of the expeller pump a setpoint value. The control device detects state values of a control variable are supplied by the drive, in particular relating to the position, rotational speed and torque of the drive motor, and adjusts the displacement pump output to reach the setpoint value without using sensors.

Abstract: Apparatus are provided for motor control systems and related medical devices. In one embodiment, a control system includes a motor having a rotor, a modulation module coupled to the motor, and a control module coupled to the modulation module. The modulation module generates a modulated voltage that is applied to the motor and rotates the rotor to deliver fluid via a fluid path. The control module adjusts a duty cycle of the modulated voltage to achieve a commanded rotation of the rotor and detects an occlusion condition in the fluid path based on the duty cycle.

Abstract: A pump system including a pump and a sensor system for monitoring a fluid production of the pump and providing an output indicative of the fluid production. The sensor system is configured to use at least two discreet methodologies for measuring the fluid production. The pump system further includes a control system operatively coupled to the sensor system and the pump and configured to automatically vary the speed of the pump at least partially based upon the output of the sensor system.

Abstract: A method of controlling pressure in a mud pump system includes generating a pressure limiting factor output using a pressure feedback input and a motor speed input to calculate a fluid conductance estimate, maintaining the pressure limiting factor output at a maximum value based on a pressure set-point, continuously updating a normal fluid conductance value based on the fluid conductance estimate while the pressure limiting factor output remains at the maximum value, freezing the normal fluid conductance value, if the pressure limiting factor output is less than the maximum value, calculating a change in fluid conductance based on the normal fluid conductance value and the fluid conductance estimate, generating at least one adaptive gain based on the change in fluid conductance, and controlling a motor speed of a pump in the mud pump system based on the at least one adaptive gain.

Abstract: The present invention discloses a method and auto-control system on improving pumping system performance. The system contains a pump, a pool, pipelines, a parameter setting module, a water level measuring module and a system control module. The parameter setting module is configured to preset a characteristic parameter and a control parameter of the pump and the pipelines. The water level measuring module is configured to measure, determine and compute a high level pool water level, a flow demand trend and a system instantaneous flow at regular intervals. The system control module is configured to receive the data sent by the water level measuring module that is measured and computed, and controls the operation of the system based on the data. Compared to existing pumping control system, the system in the present invention can save energy for 10%-30%.

Abstract: In a system comprising a fuel and a rotating electrical machine, damage of a switching element is prevented when the rotating electrical machine becomes a locked state. In a power controller, it is monitored whether the rotating electrical machine is in the locked state or not. When the rotating electrical machines is judged to be in the locked state, a command for dropping output voltage is given to the fuel cell. Thus, inverter input voltage can be dropped, loss power of the switching element in the rotating electrical machine is dropped and damage can be suppressed. The rotating electrical machine is monitored to cancel the locked state or not while dropping of inverter input voltage is controlled. When the locked state is judged to be canceled, control of the fuel cell is returned to a state of regular operation control.

Abstract: A method and apparatus for optimizing energy efficiency of a pumping system includes at least one pump that controls a fluid level in a reservoir. The method includes a system identification stage and an energy efficiency optimization stage. The system identification stage includes determining pump characteristics for the pump, operating the pump with a range of flow rate conditions, determining a set of data points, and calculating energy efficiency optimization characteristics. The energy efficiency optimization stage includes determining a present static head value, choosing a value for a pump control parameter, and operating the pump on the pump control parameter.

Abstract: There is provided an electric compressor capable of being actuated rapidly. During the time when the operation of an automotive air conditioner is stopping, by heating a motor 12, a refrigerant on the outlet side 11b of a compressor body 11 is heated. Thereby, the temperature of refrigerant on the outlet side 11b is raised, and the refrigerant is prevented from being liquefied on the outlet side 11b of the compressor body 11, by which the automotive air conditioner can be actuated rapidly. Besides, by rotating the motor 12 at the number of revolutions lower than that at the time of normal operation, the refrigerant liquefied on the outlet side 11b of the compressor body 11 may be pushed out.

Abstract: A water-injected compressor, which injects the water inside the separator 3 into the compressor and discharges the water along with compressed air into the separator and then gains condensed and separated water, has the compressor stopping and then, if staying at a stop for a predetermined duration of time without activating, becoming activated and operating for a set duration of time.

Abstract: The present embodiments provide a system having a motor, a compressor having a compression device configured to increase a pressure of a gas, a clutch configured to selectively transfer torque from the motor to the compressor to drive the compression device, and a controller configured to disengage the clutch if the pressure of the gas in the compressor meets or exceeds a first threshold pressure.

Abstract: A pump apparatus has a downhole pump disposed in a wellbore and has a motor at the surface, and a rod string operatively moved by the motor reciprocates the downhole pump in the wellbore. Downhole data indicative of load and position of the downhole pump is generated using surface measurements and a wave equation model having a damping factor. Actual fluid load lines are determined from the downhole data for upstrokes and downstrokes of the downhole pump, and calculated fluid load lines for from the strokes are determined from the distribution of the load values in the downhole data. The actual fluid load lines are compared to the calculated fluid load lines to determine if the downhole data is over or under-damped. Then, the damping factor of the wave equation model can be adjusted so that new downhole data can be generated with appropriate damping.

Abstract: A fluid system includes a fluidic device, an electrically-actuated fluid pump having a pump motor, and a control system. The control system controls a speed of the pump using a commanded torque value, and calculates a feedforward torque term as a function of a set of operating values, including a desired fluid line pressure. The control system determines the speed control torque term using pump speed error, and adds the feedforward torque term to the speed control torque term to calculate the commanded torque value. The speed control torque term may be determined using an integral term of a proportional integral derivative (PID) portion of the control system. A method for controlling pump speed includes calculating the feedforward torque term, determining the speed control torque term using a pump speed error, and adding the feedforward torque term to the speed control torque term to calculate the commanded torque value.

Abstract: A compressor control device includes a driving circuit, for controllably supplying a coil of an electric motor of a compressor. A temperature sensor is thermally coupled to the driving circuit and provides a temperature sensing signal correlated to a temperature in the driving circuit. A control stage, coupled to the driving circuit and to the temperature sensor, selectively prevents the driving circuit from supplying the coil, in response to a minimum temperature increment being detected by the temperature sensor within a pre-determined control time window.

Abstract: A dry pump apparatus comprises; a pumping mechanism, a controller for controlling the operation of the pumping mechanism, and a sensor for sensing the operating temperature of the pumping mechanism. The controller is configured to carry out an automated shutdown sequence involving the following steps; a) ceasing operation of the pumping mechanism b) monitoring the temperature of the pumping mechanism by means of the temperature sensor c) at least one pre-selected temperature interval, initiating operation of the pumping mechanism for a fixed time period so as to purge a proportion of contaminant particulate matter present until a predefined temperature is reached or a predefined time limit has passed. By carrying out these steps the incidence of powder compaction between component parts of the apparatus which may contract during shutdown, and consequential restart failure and down time, can be significantly reduced.

Abstract: A system and method are provided to associate a medication name with an infusion pump and to communicate that association to a patient data management system (“PDMS”) for display and monitoring. In the case where the infusion pump does not contain a library of selectable medical fluid names that includes the name of the medical fluid to be infused, a separate computer will display a list of medical fluid names for the infusion pump and the operator may select the name of the medical fluid for that infusion pump. The computer will then continually associate that medical fluid name with that infusion pump and communicate the association to the PDMS. In the case where the infusion pump is capable of accepting an upload of new medical fluid names, the computer will upload an abbreviated list of fluid names so as not to overburden the computer with the transfer of large amounts of data.

Abstract: A refrigerant compressor includes a housing providing a refrigerant outlet having a throat. An electric motor is provided in the housing to directly drive an impeller via a shaft about an axis in response to a variable speed command. The impeller includes an outlet end aligned with variable geometry diffuser. A magnetic bearing assembly rotationally supports the shaft relative to the housing in response to a magnetic bearing command. A member is arranged to adjust the throat area, and which can move in a direction generally parallel to the axis in response to an actuator receiving a compressor regulation command. A controller is configured to respectively provide the variable speed command, the magnetic bearing command and the compressor regulation command to the electric motor to vary throat area, the magnetic bearing assembly and the actuator to obtain a desired compressor operation without the need of variable inlet geometry.

Abstract: Known water supply systems are fed from a source of water such as a tank (6) via a pump (5) to outlets which are occludable by means of a cock (C1-C3). A water pressure sensitive electrical switch (S1) is located downstream of the pump (5) and upstream of the outlets. The switch (S1) is connected in series with an electrical supply for the pump and turns the pump on in response in a drop in water pressure downstream of the switch. Similarly the pump is turned off in response to water pressure downstream to the switch reaching a predetermined minimum pressure, A control system is disclosed in the form of a timer (T) connected in parallel with the pump (5) and energized via the switch (S1). A normally closed safeguard switch (S2) is connected in series with the pump and rendered non-conductive by the timer (T) being energized for a predetermined period.

Abstract: A variable water pump control apparatus, may include a detecting portion detecting engine speed, operation of an idle stop and go system (ISG), coolant temperature, operation of a blower, and outside temperature, a variable water pump selectively circulating a coolant through an engine, and a control portion controlling the variable water pump according to the detected information including operating conditions and outside environmental factors, and a variable water pump control method may include detecting a driving condition and an environmental condition of a vehicle, and engaging or releasing a clutch of a variable water pump according to a detected condition so as to selectively circulate a coolant.

Abstract: A method for determining faults during the operation of a pump unit. At least two electric variables that determine the electric output of the motor and at least one fluctuating hydraulic variable of the pump are detected. The detected values or values formed from the variables by use of algorithms are automatically compared to predefined stored values using electronic data processing and the results of the comparison are used to determine whether or not faults have occurred.

Abstract: An air compressor includes: a tank portion for reserving compressed air used in a pneumatic tool; a compressed air generation portion for generating compressed air and supplying the compressed air to the tank portion; a drive portion including a motor for driving the compressed air generation portion; a control circuit portion for controlling the drive portion; and a pressure sensor for detecting pressure of the compressed air reserved in the tank portion. The control circuit portion includes a unit for controlling the rotational speed of the motor multistageously based on a detection signal output from the pressure sensor.

Abstract: The invention is an apparatus and method of varying power output and decrease noise generation of spa pumps by powering them with a variable frequency power device, digital signals capable of controlling cascaded pumps using ganged controls, and to decrease safety concerns of spas using an integrated water level and motion detectors.

Abstract: Some embodiments of an infusion pump system can employ a number of power management techniques to avoid using substantially excessive power during operation of the pump drive system. Thus, the infusion pump system can draw upon the energy supply in an efficient manner that extends the useful life on the power supply. Furthermore, the infusion pump system can be configured estimate an amount of power remaining to operate the pump system without the requirement of directly detecting the remaining charge on power supply device (e.g., without detecting the remaining charge on a battery). As such, the infusion pump system can readily inform a user of a particular estimated amount of time remaining for medicine dispensing operations.

Abstract: There is provided a fluidic device that is small, that can reduce contamination inclusion, and that can improve efficiency. A fluidic device includes a first constituent member internally having a first channel, and a mounting substrate internally having a second channel, the first constituent member being mounted on the mounting substrate. The mounting substrate has a storage portion for storing a fluid which is supplied to the first channel and a collecting portion for storing a fluid which is discharged from the first channel. The second channel has a supplying channel portion connected to the storage portion and a collecting channel portion connected to the collecting portion. The supplying channel portion and the collecting channel portion are connected to each other via the first channel.

Abstract: A fluid balanced hydraulic pump has a support tower that can be mounted over a well. At least one cylinder assembly is pivotally mounted within the support tower. A prime mover provides hydraulic fluid to the at least one cylinder assembly through a wedge spool control valve that provides precise speed control with minimal maintenance requirements. Stroke speed can be easily and quickly adjusted without the need for expensive, troublesome or complicated electronic equipment.

Abstract: In order to provide a compressed air manufacturing facility which can increase a stability of a supply pressure while obtaining an energy saving effect, in a compressed air manufacturing facility provided with a compressor compressing an air, an electric motor driving the compressor, and an inverter variably controlling a rotating speed of the electric motor, the compressed air manufacturing facility is provided with a pressure sensor detecting a discharge pressure of the compressor at an upstream side position of a discharge air system connected to a discharge side of the compressor, and a control apparatus computing a pressure loss of the discharge air system in correspondence to a rotating speed of the electric motor, and changing a control range of the discharge pressure of the compressor at the upstream side position of the discharge air system on the basis of the computation in such a manner that a terminal pressure at a downstream side position of the discharge air system comes to a predetermined range

Abstract: A method and apparatus for determining a fluid level and/or output flow during operation of a centrifugal pump, are provided, which may be used for production of gas and/or oil from a well, and include a vector feedback model to derive values of torque and speed from signals indicative of instantaneous current and voltage drawn by the pump motor, a pump model which derives values of the fluid flow rate and the head pressure for the pump from torque and speed inputs, a pumping system model that derives, from the estimated values of the pump operating parameters, an estimated value of fluid level and other pumping system parameters. Controllers responsive to the estimated values of the pumping system parameters control the pump to maintain fluid level at the pump input, near an optimum level, or within a safe operating range and/or output flow from the pump.

Abstract: An intelligent remote-controlled portable intravenous injection and transfusion system includes a fluid storage unit (A), a transfusion needle (B), a transfusion tube (C) and a fluid supply driving unit (D). The fluid storage unit (A) is formed by a portable bag (A1) and a fluid storage bag (A2) therein. The fluid supply driving unit (D) includes a peristaltic pump (2), which is provided in a portable flip-shell formed by a lower case (5), an upper cover (6) and a rotational axis (7), and its drive device (1), a power (13), a controller having MSF module and the second wireless signal transmitter/receiver unit. The second wireless signal transmitter/receiver unit is connected to the I/O of the controller. The first wireless signal transmitter/receiver unit is provided in a healthcare monitor room, and connected to the I/O of a computer installed with a controlling software.

Abstract: A liquid injection and ratio control system is provided for blending an additive into a main flow line at a controlled ratio. The system automatically detects variances in temperature, pressure, and additive concentration and provides compensation thereto. The system also provides for automatic flow detection, calibration responsive to a level gauge, automated data collection, and wireless bi-directional communication.

Abstract: A system is adapted to automatically maintain a desired yield level for a slurry flow. Measurements of the electrical conductivity of a slurry are taken and corrected for the effects of temperature and pressure. The corrected conductivity measurements are used to arrive at a value for system yield. The system automatically determines if the yield is too high or too low relative to a desired level, and controls the rate at which accelerator is added to the slurry in order to increase or decrease yield.

Abstract: An apparatus for supplementing a brake vacuum pressure, may include an engine control unit (ECU) that generates a vacuum pressure control signal for supplementing the brake vacuum pressure in accordance with the result of determining whether the brake vacuum pressure is included in a reference vacuum pressure range after a vehicle implements an ISG process, a sub-oil pump that is operated in accordance with a control signal from the ECU to supply hydraulic pressure to the inside of an automatic transmission after the vehicle implements the ISG process, a vacuum pump that generates and supplies the brake vacuum pressure to a brake system, and an electronic clutch that selectively couples the sub-oil pump and the vacuum pump to allow driving force of the sub-oil pump to be transmitted to the vacuum pump or to be cut, in accordance with whether the vacuum pressure control signal is sent thereto.

Abstract: A fluid system includes a fluidic device, an electrically-actuated fluid pump having a pump motor, and a control system. The control system controls a speed of the pump using a commanded torque value, and calculates a feedforward torque term as a function of a set of operating values, including a desired fluid line pressure. The control system determines the speed control torque term using pump speed error, and adds the feedforward torque term to the speed control torque term to calculate the commanded torque value. The speed control torque term may be determined using an integral term of a proportional integral derivative (PID) portion of the control system. A method for controlling pump speed includes calculating the feedforward torque term, determining the speed control torque term using a pump speed error, and adding the feedforward torque term to the speed control torque term to calculate the commanded torque value.

Abstract: The hydraulic power module 10 consists of 1) a hydraulic manifold 12 to route hydraulic fluid to the correct areas, 2) a hydraulic reservoir 14 that contains hydraulic fluid 16,3) a hydraulic pump 18,4) a DC servo motor 20,5) a directional valve 22,6) a cooling system 24 7) an integrated filter housing 26 and 8) electronics—motor control 28 for controlling the DC servo motor 20.

Abstract: A method to operate an electronically controlled air compressor powered by an internal combustion engine, wherein the air compressor is selectively activated when the air compressor minimum threshold value differs from the air compressor minimum threshold hysteresis by a predetermined value, and is deactivated when the air compressor maximum threshold value and the air compressor maximum threshold value hysteresis value differ by a predetermined value.

Abstract: A method for attenuating hydraulic pump flow pulses is described. The method includes pumping a fluid at a first hydraulic flow rate to an operating device via the pump, the flow being in the form of discrete fluid pulses. Further, the method includes obtaining values of plurality of parameters related to the pulses produced by the pump and attenuating the pulses by modifying the first hydraulic flow rate to a second hydraulic flow rate based on the obtained values.

Abstract: Forces on and respective positions of a pump jack sucker rod are determined in real time by load cells attached to the sucker rod and a position sensor, and are stored for further processing. A wireless transmitter transmits stored load and position values, calculated process parameters, and/or exception alerts to a wireless spread spectrum receiver that can be coupled to a motor speed controller used to set the rotational speed of the pump jack motor, and/or to monitoring systems, such as a central controller used to optimize total field production.

Abstract: A method of operating an electrical submersible pumping system that includes realtime monitoring of the wellbore fluid and adjusting pump speed so the fluid entering the pump remains subcooled. The method can include adding sensors within the wellbore and digitally storing fluid data accessible by a pump controller. The pump speed can be increased or decreased by adjusting the frequency of the electrical power delivered to the pump motor.

Abstract: Apparatus for maintaining differential internal fluid pressure in a dual fluid chamber object where it is desired for one chamber to have greater internal pressure than the other includes a sensor for generating a differential signal indicating the difference in pressure between the chambers, a pressure sensor for generating a pressure signal indicating the pressure inside the chamber desired to have less pressure, a comparator for generating a first output when the differential signal is less than a predetermined minimum differential value, a second comparator for generating a second output when the pressure signal is less than a predetermined minimum pressure value, where the predetermined minimum pressure value biased by the first output, and blowers coupled to the respective chambers and responsive to said first and second outputs respectively.

Abstract: One form of a hydrogen operated power system according to this invention is a fuel cell system (20) provided with a supply system which supplies a gaseous fuel from a fuel supply tank (24) to a fuel cell (22), characterized in that a pump (32) is provided in the supply system, which is driven by a sensorless motor (34) having no sensor that detects at least a rotational position of the motor (34).

Abstract: If the ambient temperature of a pressure volute measured by a temperature sensor exceeds 0° C., a compressor is instantly started at normal operation. If the temperature of the pressure volute measured by the temperature sensor is 0° C. or lower, vibration along the axial direction is given to the rotary shaft by way of an axial magnetic bearing. If the vibration amplitude of the thus given vibration exceeds a predetermined value, the compressor is started at normal operation after idle operation. On the other hand, if the vibration amplitude is lower than a predetermined value, the heater is actuated to heat the pressure volute only for a predetermined time. Thereafter, the ambient temperature is detected again, and if the ambient temperature exceeds 0° C., the compressor is started.

Abstract: A transport refrigeration system is provided with a control apparatus including an inverter and a microprocessor, with the microprocessor receiving signals representative of sensed values of the compressor discharge temperature and pressure, as well as the suction pressure, and controlling the inverter to responsively provide a selective level of electrical voltage and frequency to the compressor in order to maintain a desired compressor envelope.

Abstract: An electronic device having a first motor which rotates a rotating body (for example, blades) about a rotation axis and a second motor which vibrates a vibrator including the rotating body in the axial direction is provided. A control IC unit has a first circuit which subjects the rotation to control drive by a first waveform, and a second circuit which subjects the vibration to control drive by a second waveform. Rotation and vibration of a rotating and vibrating unit driven by the first and second motors generates an airflow and output sound by a synthesized output of a first output corresponding to the rotation and a second output corresponding to the vibration. The control IC unit generates a second waveform by using a reversed-phase waveform with respect to the first waveform or the like and suppresses the output sound by control of the first and second waveforms.

Abstract: The present invention relates to a fan control system. The fan control system includes a first micro controller, a second micro controller and a first logic circuit. The first micro controller provides at least one first control signal. The second micro controller is connected to the first micro controller. The second micro controller detects operational status of the first micro controller, and provides at least one second control signal. The first logic circuit receives the first control signal and the second control signal to process logic operation and to generate at least one driving signal to fan. The fan control system of the invention utilizes two micro controllers, when one of the two micro controllers malfunctions, the first logic circuit allows the other micro controller to continue proper operation of the fan, thereby preventing the problem of insufficient heat dissipation that results from malfunction of the single micro controller of a conventional fan control system.

Abstract: A medical pump with an improved continuity low flow delivery system and method for use with a pumping chamber, for example in a cassette, is disclosed. The pump includes a pump drive for exerting a force on the pumping chamber and a sensor for sensing the force/pressure exerted by the pump drive on the pumping chamber. The pump drive position sensor senses the position of the pump drive. The medical pump also includes a processing unit and a memory having a programming code adapted to calculate the rate of change of the sensed force/pressure values and determine whether the rate of change of the sensed force/pressure values meets a rate of change threshold. Once the rate of change threshold is met, the programming code is adapted to calculate a remaining pump drive travel value for determining how much farther the pump drive should travel before the end of an effective pump cycle.