The 19th International Conference on Climbing and Walking Robots and Support Technologies for Mobile Machines

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2 REACTIVE MOTION PLANNING FOR MOBILE CONTINUUM ARM IN DYNAMIC INDUSTRIAL ENVIRONMENT Ahmad Ataka, Ali Shiva, Ali Shafti, Helge Wurdemann, and Kaspar Althoefer The 19th International Conference on Climbing and Walking

3 Industrial Manipulators RIGID-LINK MANIPULATORS PRECISE POSITION CONTROL WIDELY USED WORKS SEPARATELY FROM HUMAN DUE TO SAFETY REASON MANIPULATION ONLY VIA END EFFECTOR IN GENERAL NEED OPEN SPACE The 19th International Conference on Climbing and Walking

4 Continuum Manipulators HIGHER FLEXIBILITY Able to bend at any point Possess inherent compliance IMPROVED DEXTERITY Able to perform whole-arm manipulation McMahan, et al, ICRA 2006 WIDER APPLICATION Able to manoeuvre in tight space Applied for surgical application Promising candidate for industrial manipulation The 19th International Conference on Climbing and Walking Mahl, et al, T-Ro, 2014

5 Continuum Manipulators COMPLEX MODELLING Highly-flexible structure Complex dynamic DIFFICULT TO CONTROL Nonlinearity DIFFICULT TO ESTIMATE THE POSE Xiao, et al, IROS 2010 Torres, et al, IROS 2011 LACKS AUTONOMY Research on going Assume static and well-defined environment Lacks constraint avoidance

6 Tendon-Driven Continuum Manipulator Constant-Curvature 3-Segment with Mobile Base

7 Obstacle and Constraint Avoidance

8 Modified Potential Field: Obstacle Avoidance ICRA 2016, Sweden ATTRACT END EFFECTOR TO GOAL REPEL OBSTACLE FROM ROBOT S BODY POTENTIAL FIELD AS A VELOCITY TASK-SPACE INVERSE JACOBIAN PRODUCING FIELD IN ACTUATOR SPACE Attractive field: Repulsive field:

9 Modified Potential Field: Constraint Avoidance TENDON S LENGTH LIMIT: APPLIED IN ACTUATOR SPACE: ATTRACT TENDON TO NORMAL LENGTH DEPEND ALSO ON THE DISTANCE BETWEEN TIP AND TARGET: Weight function depend on tip-to-targetdistance : The proposed mechanical constraint avoidance:

10 Simulation Results

11 Simulation Results With Constraint Avoidance Without Constraint Avoidance

12 Experimental Results Tip s trajectory Target trajectory Tip-obstacle distance Target-obstacle distance

13 Pose Estimation and Safer Obstacle Avoidance for Continuum Manipulator

14 State-Space Representation for Pose Estimation TENDON S LENGTH AS A STATE: THE RATE OF TENDON S LENGTH AS AN INPUT: STATE EQUATION: OUTPUT EQUATION:

15 Local Observability Analysis for Single-segment Linearized Model: Jacobian: Observability Matrix: Observable Condition:

16 Pose Estimation for Single-Segment IEEE BioRob 2016, Singapore MEASUREMENT: POSITION SENSOR (MAGNETIC-BASED TRACKER) AT THE TIP EKF PRODUCES THE STATE ESTIMATION THE STATE ESTIMATION USED TO ESTIMATE THE POSE OF THE WHOLE BODY AND PSP:

17 Simulation Results Zero Input Scenario Tendon s Length Estimation Zero Input Scenario Tip Pose Estimation Sinusoidal Input Scenario Tendon s Length Estimation Sinusoidal Input Scenario Tip Pose Estimation

18 Simulation Results Obstacle Close to Middle Part of Segment Obstacle Close to the Tip

19 Pose Estimation for Multi-Segment IROS 2016, Korea IMPLEMENTING STANDARD EKF HAS PROBLEM Possible to arrive at physically impossible state, such as negative length active segment n MULTI-STAGE EKF: Implement EKF graduallyfrom the bottom segment to the distal one EKF is used for n number of active segment A number of active segment n is incremented after the tip s position error of the previous segment is lower than a value

20 Pose Estimation for Multi-Segment COMBINING POSE ESTIMATION AND OBSTACLE AVOIDANCE: Combining pose estimation and obstacle avoidance from the beginning incorrect pose estimation & incorrect movement. Necessary to deactivate the obstacle avoidance stage at the beginning of estimation process Activate it when the sum of the tip position estimation errors for all segments is less than a predefined threshold

21 Simulation Results Zero Input Multi-Stages EKF Standard EKF Tendon s Length Estimation Pose Estimation Tendon s Length Estimation Pose Estimation

22 Simulation Results Sinusoidal Input Tendon s Length Estimation Pose Estimation

23 Simulation Results Obstacle Close to Bottom Segment Obstacle Close to Middle Segment

24 Possible Application to Industrial Setting

25 Combined with Rigid-Link Manipulator THE PRECISE POSITION CONTROL OF RIGID-LINK MANIPULATOR FLEXIBILITY AND DEXTERITY OF CONTINUUM MANIPULATOR

26 Ahmad Ataka Awwalur Rizqi The Centre for Robotics Research King s College London Strand, WC2R 2LS England, United Kingdom +44 (0) ahmad.ataka@kcl.ac.uk 2016 King s College London. All rights reserved