Development of Foot System of Biped Development of Foot System of Biped Walking Robot Capable of Walking Robot Capable of Maintaining Four-point ContactMaintaining Four-point Contact

Intelligent Robots and Systems, 2005. (IROS 2005). 2005 IEEE/RSJ International Conference on Publication Year: 2005 , Page(s): 1361 – 1366

指導教授：邱俊賢學 生：莊順德

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OutlineOutlineAbstractINTRODUCIONFOOT SYSTEM DESIGN Locking Mechanism Cam-type Locking MechanismEXPERIMENTAL TESTS AND

ONSIDERATIONCONCLUSIONS

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AbstractAbstract• In this paper, a new foot system, WS-1

(Waseda Shoes - No.1), is proposed to maintain four-point contact.

• This foot system consists of cam-type locking mechanism.WS-1 is attached to the feet of WL-16 (Waseda Leg - No.16) that is the world's first biped-walking robot capable of carrying a human.

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INTRODUCIONINTRODUCIONTo achieve biped locomotion, some

people have studied on motion pattern generation methods, while other people have researched on real-time stability control methods.

Most methods have been studied assuming that the feet of a biped walking robot should contact the ground as four points in a single support phase.

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When a biped walking robot with rigid and flat soles walks on uneven terrain, a support polygon formed by its foot becomes small due to the failure of four-point contact.

So, this paper describes a new foot system, WS-1 (Waseda Shoes - No.1) that can contact on the ground as four points.

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II. FOOT SYSTEM DESIGNII. FOOT SYSTEM DESIGNIt is difficult for biped walking robots to

walk stably on uneven bumpy terrain with 20 mm even though a real-time stability control method is employed.

So, the movable range on Z-axis of a new foot system, WS-1, is set at 20 mm.

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Locking MechanismLocking MechanismA locking mechanism will be the most

important element for the development of a foot system.

It must withstand the impact of a landing foot and retain the locking function during walk motion.

If the locking mechanism is complicated, the foot system might be heavy. So, a simple locking mechanism is required.

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Cam-type Locking MechanismCam-type Locking MechanismThe operation principle is that the cam

rotates according to the movement of the tip, the block is inserted into the space where the width narrows, and the supporting legs are locked.

This is based on the wedge mechanism. Moreover, the simplicity of the mechanism also helps to reduce the weight.

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Waseda Shoes - No.1Waseda Shoes - No.1The cam-type locking mechanisms are

arranged in the four corners, and the shape of the cam and the brake angle were decided to achieve a movable range of 20 mm on Z-axis.

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Considering that the movable range on Z-axis is set at 20 mm,this foot system is very light.

Microswitches are used for ground detection, and they are arranged at the tip of the locking mechanism

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A solenoid was selected as an actuator as well as the slidetype locking mechanism. Solenoids are controlled by reading the output of the microswitches.

When all of the foot spikes reach the ground,solenoids are energized and the cams are locked.

when all of the foot spikes leave the ground, solenoids are energized in the opposite direction and the locks are released

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EXPERIMENTAL TESTS AND EXPERIMENTAL TESTS AND CONSIDERATIONCONSIDERATIONThe newly foot module, WS-1, proposed

in this research is universally designed. It can be applied to all biped robots.

To evaluate the foot system, two experiments are conducted using the multi-purpose biped locomotor WL-16.

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Firstly, an acrylic board with thickness of 12 mm was placed on a flat floor, and a surface with dummy unevenness was created.

From the ZMP trajectories, we can see a little difference between the reference and measured ZMPs on even and uneven terrain respectively.

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Secondly, the walking experiment was conducted in the public road in Fukuoka Special Zones for Robot Development and Test.

The foot was changed to the following three types; (i) rigid and flat sole,(ii) WS-1 without activation, and(iii) WS-1 activated, and walking experiments with a step length of 0.1 m/step and walking cycle of 3.15 s/step were conducted.

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CONCLUSIONSCONCLUSIONSFirst, stamping experiments are realized

on the plastic board of 12mm. Second, walking experiments are achieved on the public road in the Fukuoka Special Zones for Robot Development and Test. So, the effectiveness of this foot system is confirmed.

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Thank you !!

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