Position control: Implement a simple proportional controller using first$-$order error dynamics such that the robot reaches the desired $x$ position.

Find the controller function a few lines below.

Steps:

Compute the error $x_e$ between the desired $x_d$ position and and the current $x$ position. The desired $x_d$ position and the current $x$ position are both inputs to the controller $($arguments of the controller function$).$

Multiply the position error by a gain $($for this example use a gain $k_p$ of $1\mathrm{.}15).$

Assign that value to a velocity command in the fixed $x-$direction $v_x=k_p{x}_e$

We want to control the robot's position on the fixed $x-$axis for now. Therefore, the velocity command in the fixed $y-$direction $v_y$ and the angular velocity $$ command remain zero. Then, set the linear velocity command in the mobile $x-$direction $v=v_x.$

Check that your lines of code look Ok$.$ Do not forget to set $v=v_x.$ and $=0.$