% Calc for acid pump control % % This is based on Ed Peltzers calcs for the HCL concentration and % predicted currents % % copyright (c) 2005 by W.J.Kirkwood of MBARI % February 2, 2005 % Last Modified 2/20/05 % Revision: 1.0 % % ///////////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ % % clean up from last activity clear all ; clf; % % Variable Declarations % % pH_SetPoint = 7.300 % pH target value for control volume % pH_Delta = 0 % pH difference from set point initialized % pH1 = 7.700; % pH Probe 1 value % pH2 = 7.700; % pH Probe 2 value % pH3 = 7.700; % pH Probe 3 value % pH_Valid_Max = 8.0; % Maximum allowable value for inclusion in average % pH_Valid_Min = 6.0; % Minimum allowable value for inclusion in average % PumpH20 = 720; % Sets the water pump at 720 mL/min % PumpAcid = 720; % Sets the acid pump at 720 mL/min % PumpFixedFlow = 1440; % Sets the total pump flow at maximum current % % /////////////////// Variable Reset if Enabled \\\\\\\\\\\\\\\\\\\\\\\ % This section is to input values for max and min on several variables % /////////////////// Set pH Probe Calibration \\\\\\\\\\\\\\\\\\\\\\\\\ % % Probe Calibration uses a scale of 0 to 5 volts per Ed with 2.5 being theoretical zero % There are two inputs to calibrate the probe: offset (+ or -) and slope (+) % Each probe has in calibration input of the form: % pH1_initial_calib = 7.00; % pH1_initial_calib_V = (2.500 * 7.00); % pH1_true_calib_V = (pH1_initial_calib_V + offset); units are volts sets mid-point refernce % pH2_initial_calib = 7.00; % pH2_initial_calib_V = (2.500 * 7.00); % pH2_true_calib_V = (pH2_initial_calib_V + offset); units are volts sets mid-point refernce % pH3_initial_calib = 7.00; % pH3_initial_calib_V = (2.500 * 7.00); % pH3_true_calib_V = (pH3_initial_calib_V + offset); units are volts sets mid-point refernce % /////////////////////// pH Probe Filter \\\\\\\\\\\\\\\\\\\\\\\\\ % Based on a FIFO using a reading Frequency and a Number of Samples % SampNumDefault = 10; % The number of readings used to average % FreqDefault = 2; % Reading frequency in Hertz % SampNumInput = input('Enter number of samples to tune filter : '); % K1 = logical(SampNumInput); % converts line input to logical for test % if K1 NOT 1 % SampNum = SampNumInput; % else % SampNum = SampNumDefault; % end % % FreqInput = input(' Enter the frequency you wish to sample probes at : '); % K2 = logical (FreqInput); % if K2 NOT 1 % ProbeDataFreq = FreqInput; % else % ProbeDataFreq = FreqDefault; % end % % pH1_Filter = zeros(1,SampNum); % Martrix for Probe 1 filtering % pH2_Filter = zeros(1,SampNum); % Martrix for Probe 2 filtering % pH3_Filter = zeros(1,SampNum); % Martrix for Probe 3 filtering % ////////////////////// H20 Current Estimate \\\\\\\\\\\\\\\\\\\\\ % Entered as a flow relationship to set pump volumes % First order calcs from Ed Peltzer show the relationship in the current % and pH regimes to be apporximatley linear. Based on a fix solution of acid % at 10% HCL concentration use the following ratio relationship: % Current estimate at 10 cm/sec acid flow is % This section bounds the current since the flow design is limited in capability % MinCurrent = 10; % Minimum current estimate in cm/sec % MaxCurrent = 30; % Maximum current estiamte in cm/sec % EstimateCurrent = input('Enter current in cm/sec : '); % if MinCurrent > EstimateCurrent % Current = MinCurrent; % elseif MaxCurrent < EstimateCurrent % Current = MaxCurrent; % else % Current = EstimateCurrent; % end % %%%% Current = (Current/100); % transform to liters % ////////////////////// Pump Flow Control \\\\\\\\\\\\\\\\\\\\\\\ % Two pumps run as an inverse ratio to maintain a set over flow volume % uses the estimated current relationship. % ............ Note: Pumps ordered are 4.8 ml / rev ............... % if Current = 10 % Total_Flow = 480; % Minimum ml/min from combined pumps % PumpAcid = Total_Flow / 2; % PumpFixedFlow = Total_Flow - PumpAcid; % Default total output from pumps in ml/sec % elseif Current = 30 % Total_Flow = 1440; % Maximum ml/min from combined pumps % PumpAcid = Total_Flow / 2; % PumpFixedFlow = Total_Flow - PumpAcid; % Default total output from pumps in ml/sec % else % Total_Flow = 1440 * (Current / MaxCurrent); % Minimum ml/min from combined pumps % PumpAcid = Total_Flow / 2; % PumpFixedFlow = Total_Flow - PumpAcid; % Default total output from pumps in ml/sec % end % % PumpAcidMax = PumpAcid; % PumpAcidMin = -PumpAcid; % % ////////////////// Running Control Loop \\\\\\\\\\\\\\\\\\\\\\\\\ % Start time % Necessary serial port open statements % pH_port1 = serial('COM1'); % fopen(pH_port1) % fprintf(pH_port1,'RS232?') % pH_port2 = serial('COM2'); % fopen(pH_port2) % fprintf(pH_port2,'RS232?') % pH_port3 = serial('COM3'); % fopen(pH_port3) % fprintf(pH_port3,'RS232?') % For time = T % % Read pH Probe new value at designated time % pH_read1 = fscanf(pH_port1); % pH_read2 = fscanf(pH_port2); % pH_read3 = fscanf(pH_port3); % Check probes for valid data and give notice of bad input % ******** NOTE: This section notifies of anamolous data ************* % if ((pH_Valid_Min < pH_read1) && (pH_read1 < pH_Valid_Max)) ~= 1 % 'pH Probe 1 value error :', pH_read1; % error statement % end % if ((pH_Valid_Min < pH_read2) && (pH_read2 < pH_Valid_Max)) ~= 1 % 'pH Probe 2 value error :', pH_read2; % error statement % end % if ((pH_Valid_Min < pH_read3) && (pH_read3 < pH_Valid_Max)) ~= 1 % 'pH Probe 3 value error :', pH_read3; % error statement % end % Box car filter for pH Probes: Moves most recent reading into 1st matrix % cell and pushes each cell down one % for i = 1:(SampNum - 1) % pH1_Filter(1,i+1) = pH1_Filter(1,i); % Matrix for Probe 1 filtering % pH2_Filter(1,i+1) = pH2_Filter(1,i); % Matrix for Probe 2 filtering % pH3_Filter(1,i+1) = pH2_Filter(1,i); % Matrix for Probe 3 filtering % end % % Insert new value in pH Matrix position 1 % pH1_Filter(1,1) = pH_read1; % pH2_Filter(1,1) = pH_read2; % pH3_Filter(1,1) = pH_read3; % % Sum of array elements % pH1_sum = sum(pH1_Filter); % pH2_sum = sum(pH2_Filter); % pH3_sum = sum(pH3_Filter); % % Average of each probe for filter % pH1_Avg = pH1_sum / SampNum; % Filtered output of pH probe 1 % pH2_Avg = pH2_sum / SampNum; % Filtered output of pH probe 2 % pH3_Avg = pH3_sum / SampNum; % Filtered output of pH probe 3 % % Check of filtered pH data for failure % ******** NOTE: This section lets the filter continue ************* % if ((pH_Valid_Min < pH1_Avg) && (pH1_ Avg < pH_Valid_Max)) ~= 1 % '*********** pH Probe 1 failure ************' ; % failure statement % CountProbe1 = 0; % eliminates probe from calc % pH1_Avg = 0; % zeros bad probe value % else % CountProbe1 = 1; % allows probe in calc % end % if ((pH_Valid_Min < pH2_Avg) && (pH2_ Avg < pH_Valid_Max)) ~= 1 % '*********** pH Probe 2 failure ************' ; % failure statement % CountProbe2 = 0; % eliminates probe from calc % pH2_Avg = 0; % zeros bad probe value % else % CountProbe2 = 1; % allows probe in calc % end % if ((pH_Valid_Min < pH3_Avg) && (pH3_ Avg < pH_Valid_Max)) ~= 1 % '*********** pH Probe 3 failure ************' ; % failure statement % CountProbe3 = 0; % eliminates probe from calc % pH3_Avg = 0; % zeros bad probe value % else % CountProbe3 = 1; % allows probe in calc % end % GoodProbes = CountProbe1 + CountProbe2 + CountProbe3; % Total good probes % % Check to see if all the probes have failed and system is uncontrolled % if GoodProbes = 0 % '!!!!!!!!! Probes Have Failed - Exiting Control Loop !!!!!!!!'; % ' Exiting Program '; % Stop Time % Terminate program % end % % Completed pH probe filter output for control % pH_Control = (pH1_Avg + pH2_Avg + pH3_Avg) / GoodProbes; % % Main Control Algorithm for Pumps % Concept: We would like the pump control to be exponential as the pH % wanders from the set point. This makes our control take the form % y = f(x) + K = a*2^(b*(x-h))+k % y is the acid pump commanded output % % a = scalar multiplier and moves the zero crossover on the x axis, also % change of sign of a flips the control curve around the x axis % a = .4; % % b = exponential multiplier and sets the rate of change of the slope of % the control curve, also a sign change flips the control curve around the y axis % b = 2.0; % % h is the x offset constant and sets the x crossover at y = 0 % h = .5; % % K is the y offset constant and sets the y crossover at f(x) = 0 % K = 720; % scaled in ml/min % % % pH Bounds lower is - .1 pH unit and upper is + .1 pH unit for deadband % pH_BoundLow = pH_SetPoint - .10; % pH_BoundHigh = pH_SetPoint + .10; % % Control Tests for sign on equation variables a, b, and K to invert curve % about dead band % % if pH_Control < pH_BoundLow % a = -a; % b = -b; % K = -K; % end % % Set scaling for pump adjust % % pH_expo = b*(pH_Control - h); % pH_X = a*(2^pH_expo); % PumpAdjNum = pH_X + K; % % Acid Flow Clipping Equation goes here % % if (PumpAdjNum > PumpAcidMax ) % NewAcidNum = PumpAcidMax; % elseif (PumpAdjNum < PumpAcidMin ) % NewAcidNum = PumpAcidMin; % else % NewAcidNum = PumpAdjNum; % end % % Pump adjust test vs. pH % % if pH_Control > pH_BoundMax % PumpCmd % % % slaving acid pump rate to the pH_Control variable % pH_Delta = pH_SetPoint - pH_Control; % pH offset from desired value % % tests and settings for acid volume change % if pH_Delta < 0 % PumpAdjNum = pH_Delta_Old - pH_Delta; % PumpAcid = PumpAcid; % no change to pump input % PumpFixedFlow = Total_Flow - PumpAcid; % Default total output from pumps in ml/sec % elseif pH_Delta > 0 % PumpAcid = Total_Flow / 2; % PumpFixedFlow = Total_Flow - PumpAcid; % Default total output from pumps in ml/sec % else % PumpAcid = PumpAcid; % no change in pump flow % end % pH_Delta_Old = pH_Delta; % resets pH for comparison to last value % pH_PumpAcid_Old = pH_PumpAcid; % resets Acid Pump flow rate comparion to last value % % Shutdown and clean up % Stop time % fclose(pH_port1) % fclose(pH_port2) % fcloae(pH_port3)