perturb_esc_nd.cpp

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/*
 * perturb_esc_nd.cpp
 *
 *  Created on: Aug 1, 2012
 *      Author: Berk Calli
 *      Organization: Delft Biorobotics Lab., Delft University of Technology
 *      Contact info: b.calli@tudelft.nl, web: www.dbl.tudelft.nl
 *
 * Class for perturbation based extremum seeking control
 *
 * * References:
 * - K. B. Ariyur and M. Krstic, "Real-Time Optimization by Extremum-Seeking Control", Wiley, 2003.
 * - B. Calli, W. Caarls, P. Jonker, M. Wisse, "Comparison of Extremum Seeking Control Algorithms for Robotic Applications", IROS 2012.
 *
 */

#include "esc_perturb/perturb_esc_nd.h"

PerturbESCND::PerturbESCND(){
        sin_amp_ = 0;
        sin_freq_ = 0;
        corr_gain_ = 0;
        high_pass_pole_ = 0;
        low_pass_pole_ = 0;
        comp_pole_ = 0;
        comp_zero_ = 0;
        period_ = 0;
        state_initialized_ = false;
        initialized_ = false;
        old_vals_initialized_ = false;
}
PerturbESCND::PerturbESCND(double sin_amp, double sin_freq, double corr_gain, double high_pass_pole, double low_pass_pole, double comp_zero, double comp_pole, double period){
        init(sin_amp, sin_freq, corr_gain, high_pass_pole, low_pass_pole, comp_zero, comp_pole, period);
}
void PerturbESCND::init(double sin_amp, double sin_freq, double corr_gain, double high_pass_pole, double low_pass_pole, double comp_zero, double comp_pole, double period){
        sin_amp_ = sin_amp;
        sin_freq_ = sin_freq;
        corr_gain_ = corr_gain;
        high_pass_pole_ = high_pass_pole;
        low_pass_pole_ = low_pass_pole;
        comp_pole_ = comp_pole;
        comp_zero_ = comp_zero;
        period_ = period;
        obj_val_old_ = 0;
        cycle_count_ = 0;
        hpf_out_old_ = 0;
        opt_dim_ = 0;
        state_initialized_ = false;
        old_vals_initialized_ = false;
        initialized_ = true;
}

std::vector<double>  PerturbESCND::step(std::vector<double> state, double obj_val){

        if(!initialized_){
                fprintf(stderr,"The perturbation based ESC (1D) is not initialized... It will not be executed. \n");
                return std::vector<double>();
        }

        if(!state_initialized_ && state.empty()){
                fprintf(stderr,"The state value of the perturbation based ESC (1D) cannot be initialized: State vector is empty. The algorithm will not be executed. \n");
                return std::vector<double>();
        }

        else if(!state_initialized_){

                opt_dim_ = (unsigned int)state.size();
                lpf_out_old_.resize(opt_dim_);
                signal_demodulated_old_.resize(opt_dim_);
                comp_old_.resize(opt_dim_);
                corr_signal_.resize(opt_dim_);
                pos_ref_.resize(opt_dim_);
                for (size_t i = 0; i<opt_dim_; i++){
                        pos_ref_[i] = state[i];
                        lpf_out_old_[i] = 0;
                        signal_demodulated_old_[i] = 0;
                        comp_old_[i] = 0;
                        corr_signal_[i] = 0;
                }

                phase_shift_.resize(opt_dim_);
                phase_shift_[0] = 0;
                for (size_t i = 1; i<opt_dim_; i++){
                        phase_shift_[i] = i*PI/((double)opt_dim_);
                }
                state_initialized_ = true;
        }

        double hpf_out = (-(period_*high_pass_pole_-2)*hpf_out_old_+2*obj_val-2*obj_val_old_)/(2+high_pass_pole_*period_);
        hpf_out_old_ = hpf_out;
        obj_val_old_ = obj_val;
        std::vector<double> signal_demodulated(opt_dim_);
        std::vector<double> lpf_out(opt_dim_);
        std::vector<double> comp_out(opt_dim_);
        std::vector<double> output;

        for (size_t i = 0; i<opt_dim_; i++){
                signal_demodulated[i]= hpf_out*sin_amp_*std::sin(cycle_count_*period_*sin_freq_ + phase_shift_[i]);
                lpf_out[i] = ((2.0-low_pass_pole_*period_)*lpf_out_old_[i]+low_pass_pole_*period_*signal_demodulated[i]+low_pass_pole_*period_*signal_demodulated_old_[i])/(2.0+low_pass_pole_*period_);
                comp_out[i]= ((2.0+period_*comp_zero_)*lpf_out[i]+(period_*comp_zero_-2.0)*lpf_out_old_[i]-(period_*comp_pole_-2.0)*comp_old_[i])/(2.0+period_*comp_pole_);
                corr_signal_[i] = corr_signal_[i]+corr_gain_*comp_out[i]*period_;
                if(!old_vals_initialized_)
                        pos_ref_[i] = sin_amp_*std::sin(cycle_count_*period_*sin_freq_ + phase_shift_[i]);      //modulation
                else
                        pos_ref_[i] = corr_signal_[i]+sin_amp_*std::sin(cycle_count_*period_*sin_freq_ + phase_shift_[i]);      //modulation
                output.push_back(pos_ref_[i]);
                signal_demodulated_old_[i] = signal_demodulated[i];
                lpf_out_old_[i] = lpf_out[i];
                comp_old_[i] = comp_out[i];
        }
        old_vals_initialized_ = true;
        cycle_count_++;

        return output;
}

ESC::inputType PerturbESCND::getInputType(){
        return ESC::inputStateValue;
}

ESC::outputType PerturbESCND::getOutputType(){
        return ESC::outputPosition;
}

std::vector<double> PerturbESCND::monitor(){
        std::vector<double> monitor_values;

        for(size_t i = 0; i<opt_dim_; i++)
                monitor_values.push_back(corr_signal_[i]);

        return monitor_values;
}
std::vector<std::string> PerturbESCND::monitorNames(){
        std::vector<std::string> monitor_names;
        std::string base = "correction signal ";
        char numstr[21];
        for(size_t i = 0; i<opt_dim_; i++){
                sprintf(numstr, "%zd", i+1);
                monitor_names.push_back(base + numstr);
        }

        return monitor_names;
}

void PerturbESCND::reset(){
        obj_val_old_ = 0;
        cycle_count_ = 0;
        hpf_out_old_ = 0;
        opt_dim_ = 0;
        state_initialized_ = false;
        old_vals_initialized_ = false;
}