docs(crosswalk): update ttc vs ttv docs (#10025)

Signed-off-by: yuki-takagi-66 <[email protected]>

planning/behavior_velocity_planner/autoware_behavior_velocity_crosswalk_module/README.md

@@ -138,27 +138,24 @@ The decision is based on the following variables, along with the calculation of
 
 We classify ego behavior at crosswalks into three categories according to the relative relationship between TTC and TTV [1].
 
-- A. **TTC >> TTV**: The object has enough time to cross before the ego.
+- A. **TTC >> TTV**: The object will pass early enough than the ego reach the collision point.
   - No stop planning.
 - B. **TTC ≒ TTV**: There is a risk of collision.
   - **Stop point is inserted in the ego's path**.
-- C. **TTC << TTV**: Ego has enough time to cross before the object.
+- C. **TTC << TTV**: The ego will pass early enough than the object reach the collision point.
   - No stop planning.
 
+The following figure shows the decision result for each TTC and TTV with the parameters, `ego_pass_first_margin_x` is `{0}`, `ego_pass_first_margin_y` is `{4}`, `ego_pass_later_margin_x` is `{0}`, and `ego_pass_later_margin_y` is `{13}`.
+
 <div align="center">
     <table>
         <tr>
             <td><img src="./docs/virtual_collision_point.svg" width="600"></td>
-            <td><img src="./docs/ttc_vs_ttv.drawio.svg" width="350"></td>
+            <td><img src="./docs/ttc_vs_ttv.svg" width="350"></td>
         </tr>
     </table>
 </div>
 
-The boundary of A and B is interpolated from `ego_pass_later_margin_x` and `ego_pass_later_margin_y`.
-In the case of the upper figure, `ego_pass_later_margin_x` is `{0, 1, 2}` and `ego_pass_later_margin_y` is `{1, 4, 6}`.
-In the same way, the boundary of B and C is calculated from `ego_pass_first_margin_x` and `ego_pass_first_margin_y`.
-In the case of the upper figure, `ego_pass_first_margin_x` is `{3, 5}` and `ego_pass_first_margin_y` is `{0, 1}`.
-
 If the red signal is indicating to the corresponding crosswalk, the ego do not yield against the pedestrians.
 
 <div align="center">