Kensuke Harada∗1, Tokuo Tsuji∗2, Kohei Kikuchi∗3

Kazuyuki Nagata∗1, Hiromu Onda∗1, Yoshihiro Kawai∗1

∗1 National Inst. of AIST∗2 Kyushu Univ.

∗3 Toyota Motors Co. Ltd.

National Institute ofAdvanced Industrial Science and Technology (AIST)

Base Position Planning for Dual-arm Mobile ManipulatorsPerforming a Sequence of Pick-and-place Tasks

INTRODUCTIONParts Supply Task

Collect necessary parts from the storage area

Determine a sequence of the base position

Selective Use of Two Hands

Can Reduce the Number of Sequence

Dual-arm Mobile ManipulatorPerforming Parts-Supply Task

OVERVIEW OF PROPOSED METHOD

Dual-arm mobile manipulator collects one part from each box.

Shipping Carton

Example

OVERVIEW OF PROPOSED METHOD

Region on base position where right hand can grasp an object in the box 1

Region on base position where left hand can grasp an object in the box 1

OVERVIEW OF PROPOSED METHOD

Obtain region on base position for all the boxes

OVERVIEW OF PROPOSED METHOD

Obtain a sequence of base position

OVERVIEW OF PROPOSED METHODMinimize : Number of Sequence and Travel Distance

Common Area of Base position: ・ Left Hand Picks an Object in the Box 1・ Right Hand Pick an Object in the Box 2

Minimizing the travel distance

FEATURES OF PROPOSED METHOD

• Objects stored in a box is known• The number and the pose are not known

• Stable grasp • Collision avoidance when grasping

• Minimizing the number of sequence• Minimizing the travel distance

Base Position Planning for Dual-arm Mobile ManipulatorsPerforming a Sequence of Pick-and-place Tasks

RELATED WORKS

Base Position for Mobile Manipulator Maximizing the Manipulability F.G.Pin et al. (1990), H. Seragi et al. (1993), K. Tchon et al. (2000) 等

Base Position Considering the Stable GraspR. Diankov et al. (2008), N. Vahrenkamp et al. (2012)

Manipulation Planner for Dual-arm ManipulatorY. Koga et al. (1994), J.-P. Saut et al. (2010), K. Harada et al. (2012)

IN THIS PRESENTATION

1. Inverse Kinematics Considering the Stable Grasp

2. Region on Mobile Base

3. Formulation of Optimization Problem

4. Numerical Examples

INVERSE KINEMATICS CONSIDERING THE STABLE GRASP （ 1/3 ）

Collision Avoidance

Joint Limit

Ellipsoidal Approximation of Links and Environments

Using EQuadProg++

QP Problem to Obtain Joint Velocity

INVERSE KINEMATICS CONSIDERING THE STABLE GRASP （ 2/3 ）Grasping Posture Database

• Quadratic Approximation of Object Surface

• Grasp Planning

• Construction of Grasping Posture Database

INVERSE KINEMATICS CONSIDERING THE STABLE GRASP （ 3/3 ）

1. Connect Initial Pose and 1st Data using Straight Line Segment

2. Split Segment into Small Steps

3. Solve QP Problem for Each Step

4. If QP problem does not have solution, proceed to next data

Search for the Grasping Posture Database

IN THIS PRESENTATION

1. Inverse Kinematics Considering the Stable Grasp

2. Region on Mobile Base

3. Formulation of Optimization Problem

4. Numerical Examples

REGION ON MOBILE BASE

Object pose is not known

Mobile Base Pose Stably Grasping of an Object

Discretize the Box / Moving Area

REGION ON MOBILE BASESearching Algorithm

STEP1Base Pose Stably Grasping All Objects in the Box

Using Multi-thread

REGION ON MOBILE BASESearching Algorithm

STEP1

STEP2Checking Neighboring Points

Base Pose Stably Grasping All Objects in the Box

REGION ON MOBILE BASE

STEP1

STEP2Checking Neighboring Points

Base Pose Stably Grasping All Objects in the Box

Searching Algorithm

REGION ON MOBILE BASESearching Algorithm

STEP1

STEP2Checking Neighboring Points

Base Pose Stably Grasping All Objects in the Box

REGION ON MOBILE BASESearching Algorithm

STEP1

STEP2Checking Neighboring Points

Base Pose Stably Grasping All Objects in the Box

IN THIS PRESENTATION

1. Inverse Kinematics Considering the Stable Grasp

2. Region on Mobile Base

3. Formulation of Optimization Problem

4. Numerical Examples

DEFINITION

P1 P2 P3 P4 P5 P6

P = [P1 P2 P3 P4 P5 P6]P2P1∩ P3P2∩ P4P3∩ P6P5∩

s=[ 1, 2, 3, 4, 5, 6, (1,2), (2,3), (3,4), (5,6)] =[ s1, s2, s3, s4, s5, s6, s7, s8, s9, s10]

FORMULATION

Which Area to Visit 　　　 0-1 Knapsack Problem

Minimizing: Number of Sequence 　　　 Branch and Bound (BB) Method

Number of Sequence

FORMULATION

Order of Area to Visit

Minimizing: Traveling Distance 　　　　　　　 Traveling Salesman Problem

Simulated Annealing

EXAMPLES

Discretizing Box Area

Region on Mobile Base Realizing the Stable Grasp

Region (Grasped by Left Hand)

Nextage + Mobile Base

Region (Grasped by Right Hand)

RESULTSDistance between Two Boxes : 0

1st Base Position ： Pick an Object from Boxes 1, 2, 3 and 4

RESULTS

1st Base Position : Pick an Object from Boxes 1 and 22nd Base Position : Pick an Object from Boxes 3 and 4

Distance between Two Boxes : 0.4 [m]

RESULTSDistance between Two Boxes : 0.8 [m]

1st Base Position : Pick an Object from Box 12nd Base Position : Pick an Object from Box 23rd Base Position : Pick an Object from Box 34th Base Position : Pick an Object from Box 4

EXAMPLES

1st Base Position

2nd Base Position

Initial Pose

CALCULATION TIME

This method is to be used for offline calculation of base position

SUMMARY• A sequence of the base position is planned for dual-arm

mobile manipulators performing multiple pick-and-place tasks.

• A robot can selectively use either the right or the left hand to pick up an object and can minimize the sequence size of the base position.

• A region on the base position is obtained where a robot

can pick up an object placed anywhere in a box. • A sequence of base positions is obtained by combining the

branch and bound and simulated annealing methods.