SOH关于IMU进行姿态求解的C代码，里面包含了两套代码，分别是重力约束法求解和梯度下降法求解_matlab

classdef MahonyAHRS < handle %MAYHONYAHRS Madgwick's implementation of Mayhony's AHRS algorithm % % For more information see: % http://www.x-io.co.uk/node/8#open_source_ahrs_and_imu_algorithms % % Date Author Notes % 28/09/2011 SOH Madgwick Initial release %% Public properties properties (Access = public) SamplePeriod = 1/256; Quaternion = [1 0 0 0]; % output quaternion describing the Earth relative to the sensor Kp = 1; % algorithm proportional gain Ki = 0; % algorithm integral gain end %% Public properties properties (Access = private) eInt = [0 0 0]; % integral error end %% Public methods methods (Access = public) function obj = MahonyAHRS(varargin) for i = 1:2:nargin if strcmp(varargin{i}, 'SamplePeriod'), obj.SamplePeriod = varargin{i+1}; elseif strcmp(varargin{i}, 'Quaternion'), obj.Quaternion = varargin{i+1}; elseif strcmp(varargin{i}, 'Kp'), obj.Kp = varargin{i+1}; elseif strcmp(varargin{i}, 'Ki'), obj.Ki = varargin{i+1}; else error('Invalid argument'); end end; end function obj = Update(obj, Gyroscope, Accelerometer, Magnetometer) q = obj.Quaternion; % short name local variable for readability % Normalise accelerometer measurement if(norm(Accelerometer) == 0), return; end % handle NaN Accelerometer = Accelerometer / norm(Accelerometer); % normalise magnitude % Normalise magnetometer measurement if(norm(Magnetometer) == 0), return; end % handle NaN Magnetometer = Magnetometer / norm(Magnetometer); % normalise magnitude % Reference direction of Earth's magnetic feild h = quaternProd(q, quaternProd([0 Magnetometer], quaternConj(q))); b = [0 norm([h(2) h(3)]) 0 h(4)]; % Estimated direction of gravity and magnetic field v = [2*(q(2)*q(4) - q(1)*q(3)) 2*(q(1)*q(2) + q(3)*q(4)) q(1)^2 - q(2)^2 - q(3)^2 + q(4)^2]; w = [2*b(2)*(0.5 - q(3)^2 - q(4)^2) + 2*b(4)*(q(2)*q(4) - q(1)*q(3)) 2*b(2)*(q(2)*q(3) - q(1)*q(4)) + 2*b(4)*(q(1)*q(2) + q(3)*q(4)) 2*b(2)*(q(1)*q(3) + q(2)*q(4)) + 2*b(4)*(0.5 - q(2)^2 - q(3)^2)]; % Error is sum of cross product between estimated direction and measured direction of fields e = cross(Accelerometer, v) + cross(Magnetometer, w); if(obj.Ki > 0) obj.eInt = obj.eInt + e * obj.SamplePeriod; else obj.eInt = [0 0 0]; end % Apply feedback terms Gyroscope = Gyroscope + obj.Kp * e + obj.Ki * obj.eInt; % Compute rate of change of quaternion qDot = 0.5 * quaternProd(q, [0 Gyroscope(1) Gyroscope(2) Gyroscope(3)]); % Integrate to yield quaternion q = q + qDot * obj.SamplePeriod; obj.Quaternion = q / norm(q); % normalise quaternion end function obj = UpdateIMU(obj, Gyroscope, Accelerometer) q = obj.Quaternion; % short name local variable for readability % Normalise accelerometer measurement if(norm(Accelerometer) == 0), return; end % handle NaN Accelerometer = Accelerometer / norm(Accelerometer); % normalise magnitude % Estimated direction of gravity and magnetic flux v = [2*(q(2)*q(4) - q(1)*q(3)) 2*(q(1)*q(2) + q(3)*q(4)) q(1)^2 - q(2)^2 - q(3)^2 + q(4)^2]; % Error is sum of cross product between estimated direction and measured direction of field e = cross(Accelerometer, v); if(obj.Ki > 0) obj.eInt = obj.eInt + e * obj.SamplePeriod; else obj.eInt = [0 0 0]; end % Apply feedback terms Gyroscope = Gyroscope + obj.Kp * e + obj.Ki * obj.eInt; % Compute rate of change of quaternion qDot = 0.5 * quaternProd(q, [0 Gyroscope(1) Gyroscope(2) Gyroscope(3)]); % Integrate to yield quaternion q = q + qDot * obj.SamplePeriod; obj.Quaternion = q / norm(q); % normalise quaternion end end end