Assignment 12

1. Angle Control of Sub-Crawler Robot on
Discontinuous Slopes
不連続斜面におけるサブクローラロボットの角度制御
S1270221 Ryoma Shoji Supervised by Prof. Keitaro Naruse

2. Today, disaster response robots are
expected to work and investigate in
areas where rescue operations by
humans are difficult by remote control.
However, it is difficult to remotely
operate robots on rough terrain, and a
mishandled operation can result in falling
over or damage to the robot. In order to
avoid such a situation, it has been
studied to overcome some obstacles by
independent driving to reduce the
number of operation errors. [1][2]
Figure 1: Disaster Response Robots
Background

3. [1]. Semi-automatic control of sub-crawler angles in
an unknown environment.
→ (Applicability A, Optimality C)
[2]. Automatic control of sub-crawler angle on stairs.
→ (Applicability C, Optimality B)
This study develops a method for automatically driving
on a discontinuous slope with a known angle by
optimizing the angle of the sub-crawler.
→ (Applicability C, Optimality A)
Figure 2 Transition diagram
for stair driving used in [1]
Figure 3 Transition diagram for stair driving
used in [2]
Related research

4. In order for the robot to perform stable and automatic
driving on discontinuous slopes, this study aims to
achieve the following two goals
 Maximize ground contact area
 Prevent the robot from falling over
Objective

5. Model to be used
Figure 4 Robot model to be used Figure 5 Slope model to be used

6. ・ Simulate a three-dimensional model using Choreonoid
Weight 80[kg]
Width 0.5[m]
Height 0.52[m]
Overall Length 1.4[m]
Maine Crawler 0.6[m]
Sub Crawler 0.4[m]
Table 2: Details of the disaster response robot model
Number of slopes Large:3
Small:6
Width 1.2[m]
Height(15[deg]) 0.3464[m]
Height(30[deg]) 0.6928[m]
Overall Length 7.2[m]
Material Steel
Table 3: Details of the slope model
Model data

7. To Maximize ground contact area
between the robot and the slope, the
angle of the sub-crawler is optimized
according to the condition of the robot
and the slope.
7
sequence 𝛉𝐟[𝐝𝐞𝐠] 𝛉𝐫[𝐝𝐞𝐠]
(1) when the tip of the FC reaches the
beginning of the slope
𝛂 + 𝛃 𝟎
(2) when the joint between FC and MC
reaches the point where the slope
begins to climb
𝛃 𝛂
(3) when the joint between RC and MC
reaches the point where the slope
begins to climb
𝟎 𝛂 + 𝛃
(4) until the joint between FC and MC
reaches the top of the slope
𝟎 𝟎
(5) when the joint between FC and MC
reaches the top of the slope
−(𝛂 + 𝛃) −(𝛂 + 𝛃)
(6) when the angle of the robot body
reaches 0°
𝟎 𝟎
(7) return to 1 and repeat steps 1~6 until
the slope ends.
Maximize ground contact area
Table 1: Data for the disaster response robot model to be used
Figure 4: A transition diagram of proposed motion

8. Determine whether the robot is stable or unstable from the
distance 𝑑 between the two points 𝑃𝑐, the point where the robot is
placed with the ground, and the projected point 𝑃𝑃 created by the
combined forces of gravity and inertia (𝐹+𝑀𝑔) on the ground.
Prevent the robot from falling over

9. 1. The proposed driving method (hereinafter called "Smart Control")
2. A driving method in which the FC and RC angles are set to 𝜶 +
𝜷[𝒅𝒆𝒈] at the apex of a slope (hereinafter called "Simple Control")
3. Running method in which the FC and RC angles are not controlled
(hereinafter called, "Uncontrol)
9
Driving Method

10. Center of gravity
1. 0.1[m]
2. 0.25[m]
3. 0.5[m]
Angle of slope
1. 15[deg]
2. 30[deg]
10
Verification Method
Figure 7: Simulation in Choreonoid

11. Center of gravity of 0.5[m] and 15[deg] slope used

12. Center of gravity of 0.25[m] and 30[deg] slope used

13. Result 15[deg] slope used

14. 14
Result 30[deg] slope used

15.  Simulations of three different control methods with different center
of gravity positions and slope angles revealed that each control
method makes a significant difference, especially when
transitioning from an uphill to a downhill slope.
 This is because the higher the center of gravity, the lower the
positional energy and the higher the kinetic energy, which in turn
increases the speed and causes the robot to hit the ground. This
happens to a large extent in Simple Control and Uncontrolled, and
the robot bounces significantly in these two control methods.
15
Discussion

16. 16
Prevent the robot from falling over
Figure 6: Right figure shows 𝑷𝒄 inside and stable, while left figure shows 𝑷𝒄 outside and unstable

17.  This verification showed that the disaster response robot can
increase the ground contact area between the robot and the
ground by optimizing the angle of the sub-crawler, and can drive
stably on a slope without falling over.
 Although verification using an actual machine was not possible
in this study, we would like to make it an actual machine in the
future so that the burden on the operator can be reduced.
17
Conclusion

18.  [1] Kazunori Ohno, Shouichi Morimura, Satoshi Tadokoro, Eiji Koyanagi, and Tomoaki Yoshida. "Semi-autonomous Control System of
Rescue Crawler Robot Having Flippers for Getting Over Unknown-Steps", Proceedings of the 2007 IEEE/RSJ International Conference on
Intelligent Robots and Systems, pages 3012-3018, 2007.
 [2] Daisuke Endo, Atsushi Watanabe, Keiji Nagatani, " Stair climbing control of 4-degrees-of-freedom tracked vehicle based on internal
sensors", Proceedings of the 2016 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR),pages 112-117,2016
 [3] "Standard Test Method for Evaluating Emergency Response Robot Capabilities: Mobility: Confined Area Terrains: Continuous Pitch/Roll
Ramps",ASTM E2826-11,2020
 [4] Takaomi Yukimura, Keiji Nagatani, Kazuya Yoshida, " サブクローラに小型測距モジュールを搭載したクローラ型移動ロボットの
階段走行の自律化", ロボティクス・メカトロニクス講演会講演概要集_1P2-E06_1 /2014巻, 2014
 [5] Shuuji Kajita, "Zero-Moment Point (ZMP) and Walking Control", 日本ロボット学 会誌, Vol 20, No. 3. pp.229~232, 2002
 [6] Daichi Yamada, "廃止措置に挑むJAEA楢葉遠隔技術開発センター",日本原子力学会誌ATOMOΣ,Vol 59, No7.pp.399~403,2017
References

19. Thank you for your attention