Design of a controller for sitting of infants

1
Design of a controller for sitting of infants

• Semester Project
• July 5, 2007

Supervised by Ludovic Righetti Prof. Auke J.
Ijspeert
Presented by Neha P. Garg
2
Content

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Introduction Motivation
• Observations
• Hand Made trajectory
• Analysis of trajectory
• Dynamical System
• Further Work
• Conclusions

3
RobotCub Project

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Aim study cognitive abilities of a child
• How by building a 2 year old infant-like
  
  
  
• humanoid robot ICUB

4
Need for Locomotion

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Cognitive Development
• Explore Environment
• Locomotion

5
Real Infants

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Two main phases of sitting
• Bringing of one leg forward
• Movement of arm to sit on hip

6
Demonstration

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Video of hand-made trajectory

7
Main Characteristics

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Torso Movement Leg Movement
  First Phase Complete
• Second Phase Start Arm Movement
  Sitting

Critical Phase
8
The Trajectory

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

9
Robustness

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Checked in only critical period
• Variation of the points specified for DOFs that
  effect critical period
• Trajectory is quiet robust

10
Robustness

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Right Arm

11
Robustness

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Torso

12
Robustness

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Right Leg

13
Center of Mass

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Can information about projection of CM during
  sitting can be used to classify transitions as
  good or bad?
• Defining stability measure as integration of
  distance of center of mass from support polygon
  with time during sitting

14
Center of Mass

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

15
Torso Speed

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Can we predict sitting/falling before critical
  period ?

16
Observations from analysis

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Clear division of sitting in two phases
• Robot unstable in the second phase
• Robustness more important than stability
• Some amount of instability required for sitting
• Torso speed cannot be used to predict
  sitting/falling

17
Two Main Tasks

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Switching from crawling to sitting
• Designing mathematical equations for sitting
  trajectories

18
Switching from crawling to sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• When an external signal S is given, robot
  should switch from crawling to sitting
• This can be done by

19
Switching from crawling to sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• This may cause abrupt shift from crawling to
  sitting
• Switching should occur only when while crawling
  hip and shoulder joints are moving in the same
  direction as they will move after shifting
• For this we replace S by

20
Switching from crawling to sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

21
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• For all of the trajectories except Left Leg
  (Abduc /Adduc and Rotation) the following
  equation can be used
• Where parameter P decides when the system should
  start and when the system starts it goes towards
  
• can also be changed if required

22
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• For example for torso pitch
• P 1
• Where S1 becomes 1 when second phase starts
• And is calculated as

23
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• For example for left knee

24
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• For Left Leg (Abduc/Adduc and Rotation), the
  movement has to be synchronized with left knee

25
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

26
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

27
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

28
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

29
Dynamical System for Sitting

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

30
Demonstration

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Crawling and Sitting using Dynamical System

31
Further Work

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Addition of sensory feedback while sitting Robot
  Falling
• Collection of biological data to know whether the
  movements while sitting are controlled by brain
  or spinal cord
• Development of controller for transition from
  sitting to crawling
• Increase in the limit up to which hip joint can
  be extended

32
Conclusions

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Main characteristics of sitting behavior of
  infants and the period of instability have been
  identified
• A controller for sitting of the robot in the same
  way as infants has been implemented
• Sensory feedback can be easily integrated by
  modifying values of parameter (P) according to
  sensory input
• Robot can be switched from crawling to sitting by
  providing an external signal

33

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• Thanks a lot!
• Questions?

34
References

• Introduction Motivation

• Dynamical System

• Observations

• Further Work

• Hand Made Trajectory

• Conclusions

• Analysis of trajectory

• 1 G. Sandini, G. Metta, and D. Vernon,
  Robotcub an open framework for research in
  embodied cognition, 2004, paper presented at the
  IEEE RAS/RJS International Conference on Humanoid
  Robotics, Santa Monica, CA.
• 2 L. Righetti and A.J. Ijspeert. Design
  methodologies for central pattern generators an
  application to crawling humanoids, Proceedings
  of Robotics Science and Systems 2006,
  Philadelphia, USA
• 3 Michel, O. WebotsProfessional Mobile Robot
  Simulation.Int. J. of Advances Robotic Systems,
  2004, pages39-42,vol.1
• 4 G. Metta, G. Sandini, D. Vernon, D. Caldwell,
  N. Tsagarakis, R. Beira, J. Santos-Victor, A.
  Ijspeert, L. Righetti, G. Cappiello, G. Stellin,
  F. and Becchi. The RobotCub project - an open
  framework for research in embodied cognition,
  Humanoids Workshop, Proceedings of the IEEE -RAS
  International Conference on Humanoid Robots,
  December 2005
• 5 MATLAB Function pchip Fritsch, F. N. and R.
  E. Carlson, "Monotone Piecewise Cubic
  Interpolation," SIAM J. Numerical Analysis, Vol.
  17, 1980, pp.238-246