The code doesn't want to run properly and it gives me many errors, can someone fix it.

Unrecognized function or variable 'R'.

Error in test>robot_kinematics (line 97)

v = R/2*(w_left+w_right);

Error in test (line 71)

xdot = robot_kinematics(x, w_left, w_right);

And here is the code:

% Robot Parameters

L = 0.2; % distance between the left and right wheels in meters

R = 0.05; % radius of the wheels in meters

% Motor Characteristics

Kv = 0.1; % motor velocity constant

Kt = 0.05; % motor torque constant

Rm = 3; % motor resistance

Lm = 0.1; % motor inductance

% Controller Parameters

Kp = 1; % proportional gain

% Line Sensor Parameters

sensor_distance = 0.1; % distance between the sensors in meters

sensor_offset = 0.05; % distance between the sensors and the center of the robot in meters

sensor_threshold = 0.5; % threshold for detecting the black line

% Initial Conditions

x0 = 0; % initial x position

y0 = 0; % initial y position

theta0 = 0; % initial orientation in radians

% State-Space Model

A = [0 0 0 0;

0 0 0 0;

0 0 0 0;

0 0 0 0];

B = [1 1 0 0;

0 0 1 1;

-1/L 1/L -1/L 1/L;

R/(2*L) R/(2*L) -R/(2*L) -R/(2*L)];

C = [1 0 0 0;

0 1 0 0;

0 0 1 0;

0 0 0 1];

D = zeros(4,4);

% Create State-Space Model

sys = ss(A,B,C,D);

% Design Controller

Q = diag([10 10 10 1]); % state cost matrix

R = 1; % input cost matrix

[K,S,e] = lqr(sys,Q,R);

controller = -K;

% Simulation Parameters

tspan = [0 10]; % simulation time interval

dt = 0.01; % simulation time step

% Simulation Loop

t = tspan(1);

x = [x0; y0; theta0; 0];

while t < tspan(2)

% Read Line Sensor

sensor_vals = read_line_sensor(x(1:2), x(3), sensor_distance, sensor_offset);

error_left = sensor_threshold - sensor_vals(1);

error_right = sensor_threshold - sensor_vals(2);

% Compute Control Input

u = controller * [error_left; error_right; 0; 0];

v_left = Kp * u(1);

v_right = Kp * u(2);

% Compute Motor Velocities

w_left = v_left / R;

w_right = v_right / R;

% Update State

xdot = robot_kinematics(x, w_left, w_right);

x = x + xdot * dt;

t = t + dt;

% Plot Robot

plot_robot(x(1), x(2), x(3), R);

drawnow;

end

function sensor_vals = read_line_sensor(pos, theta, sensor_distance, sensor_offset)

% Compute Sensor Positions

sensor1_pos = pos + sensor_offset * [cos(theta+pi/2); sin(theta+pi/2)];

sensor2_pos = pos + sensor_offset * [cos(theta-pi/2); sin(theta-pi/2)];

% Compute Line Sensor Values

sensor1_val = exp(-norm(sensor1_pos-[pos(1)+cos(theta); pos(2)+sin(theta)])^2 / sensor_distance^2);

sensor2_val = exp(-norm(sensor2_pos-[pos(1)+cos(theta); pos(2)+sin(theta)])^2 / sensor_distance^2);

% Return Sensor Values

sensor_vals = [sensor1_val; sensor2_val];

end

function xdot=robot_kinematics(~,w_left,w_right)

% Compute Forward Velocity

v = R/2*(w_left+w_right);

% Compute Angular Velocity

w = R/L*(w_right-w_left);

% Compute State Derivative

xdot=[v*cos(x(3));v*sin(x(3));w;0];

end

[IPro]

You haven't called "R" (among others) in the robot_kinematics function.

Answer 1

[Alex Batts]

Hello,

First, when copying code into a question, please use the "insert a line of code" feature for readability purposes.

Now, to answer your question, you do not have "R" defined as an input variable to your function "robot_kinematics". You also do not have "L" or "x" defined as inputs to the function either. You will want to define the function like:

function xdot=robot_kinematics(x,w_left,w_right,R,L)

Additionally, you need to replace line 71 with:

xdot = robot_kinematics(x, w_left, w_right, R, L);

However, your code will still not run because the function "plot_robot" is not defined, unless you already have this function defined on your local machine.

Alex