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/* |
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* Copyright 2014, Andrea Del Prete, LAAS-CNRS |
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* |
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*/ |
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#include <cassert> |
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#include <cmath> |
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#include <sot/torque_control/motor-model.hh> |
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/// i = Kt*tau + Kv*dq + Ka*ddq + sign(dq)Kf |
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/// tau = i/Kt - (Kv/Kt)*dq - (Ka/Kt)*ddq - sign(dq)(Kf/Kt) |
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namespace dynamicgraph { |
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namespace sot { |
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namespace torque_control { |
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MotorModel::MotorModel() {} |
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double MotorModel::getCurrent(double torque, double dq, double ddq, double Kt_p, |
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double Kt_n, double Kf_p, double Kf_n, |
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double Kv_p, double Kv_n, double Ka_p, |
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double Ka_n, unsigned int poly) { |
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assert(Kt_p > 0.0 && "Kt_p should be > 0"); |
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assert(Kt_n > 0.0 && "Kt_n should be > 0"); |
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assert(Kf_p >= 0.0 && "Kf_p should be >= 0"); |
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assert(Kf_n >= 0.0 && "Kf_n should be >= 0"); |
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assert(Kv_p >= 0.0 && "Kv_p should be >= 0"); |
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assert(Kv_n >= 0.0 && "Kv_n should be >= 0"); |
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assert(Ka_p >= 0.0 && "Ka_p should be >= 0"); |
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assert(Ka_n >= 0.0 && "Ka_n should be >= 0"); |
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double signDq = this->smoothSign(dq, 0.1, poly); // in [-1;1] |
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double current; |
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// Smoothly set Coefficients according to velocity sign |
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double Kt = 0.5 * (Kt_p * (1 + signDq) + Kt_n * (1 - signDq)); |
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double Kv = 0.5 * (Kv_p * (1 + signDq) + Kv_n * (1 - signDq)); |
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double Ka = 0.5 * (Ka_p * (1 + signDq) + Ka_n * (1 - signDq)); |
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double Kf = 0.5 * (Kf_p * (1 + signDq) + Kf_n * (1 - signDq)); |
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current = Kt * torque + Kv * dq + Ka * ddq + signDq * Kf; |
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return current; |
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} |
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double MotorModel::getTorque(double current, double dq, double ddq, double Kt_p, |
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double Kt_n, double Kf_p, double Kf_n, double Kv_p, |
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double Kv_n, double Ka_p, double Ka_n, |
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unsigned int poly) { |
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assert(Kt_p > 0.0 && "Kt_p should be > 0"); |
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assert(Kt_n > 0.0 && "Kt_n should be > 0"); |
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assert(Kf_p >= 0.0 && "Kf_p should be >= 0"); |
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assert(Kf_n >= 0.0 && "Kf_n should be >= 0"); |
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assert(Kv_p >= 0.0 && "Kv_p should be >= 0"); |
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assert(Kv_n >= 0.0 && "Kv_n should be >= 0"); |
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assert(Ka_p >= 0.0 && "Ka_p should be >= 0"); |
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assert(Ka_n >= 0.0 && "Ka_n should be >= 0"); |
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double signDq = this->smoothSign(dq, 0.1, poly); // in [-1;1] |
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double torque; |
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// Smoothly set Coefficients according to velocity sign |
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double Kt = 0.5 * (Kt_p * (1 + signDq) + Kt_n * (1 - signDq)); |
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double Kv = 0.5 * (Kv_p * (1 + signDq) + Kv_n * (1 - signDq)); |
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double Ka = 0.5 * (Ka_p * (1 + signDq) + Ka_n * (1 - signDq)); |
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double Kf = 0.5 * (Kf_p * (1 + signDq) + Kf_n * (1 - signDq)); |
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torque = |
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(current / Kt) - (Kv / Kt) * dq - (Ka / Kt) * ddq - signDq * (Kf / Kt); |
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return torque; |
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} |
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double MotorModel::smoothSign(double value, double threshold, |
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unsigned int poly) { |
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if (value > threshold) |
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return 1.0; |
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else if (value < -threshold) |
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return -1.0; |
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double a = value / threshold; |
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if (poly == 1) return a; |
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if (poly == 2 && value > 0) return a * a; |
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if (poly == 2 && value <= 0) return -a * a; |
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return a * a * a; |
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} |
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} // namespace torque_control |
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} // namespace sot |
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} // namespace dynamicgraph |