1. Force Feedback Using Electromagnetic Controller in Robotic System Presented By: Ajay Mudunuri Hasan Aatif Rohini Hiremath ECE 7995 Dr. Abhilash Pandya Wayne State University, Detroit, MI 48201

2. Summary  Introduction Background Project Aims  Method Controlling the Robotic Gripper using Hand Motions Delivery of Force Feedback  Problem and Solution  Future Work  Conclusion

3. Introduction

4. Background  The current robotic surgical systems lack tactile or haptic feedback.  The present systems to deliver force feedback include ‘Visual’ or ‘Auditory’ aids.  These systems divert the attention of the surgeon during the surgery.  This may lead to surgical errors, which might cause an irreversible injury to the patient.  Need for a system which can deliver the feedback without diverting the attention.  Feedback using Vibrators at the surgeon’s hand(Data Glove).  This might lead to more surgical error due to tremor.

5. Project Aims  To develop a mechanism to deliver force feedback through the sense of touch. Develop a system which can control a gripper using the basic hand motion (Open & Close). Detect the force applied by the gripper. Deliver it back to the user using electromagnets.  Integrate the above so that the operator controls the gripper using his hand and gets the feedback to his hand.

6. Method

7. Method: Controlling the Gripper using Hand Motions  A bend sensor is attached to the operators hand.  Resistance of the bend sensor changes depending on the position of the operator’s hand.  This way, we can identify the position of the operator’s hand.

8. Method: Controlling the Gripper using Hand Motions  The robotic gripper was built.  Controlled using a DC Motor.  Can perform the basic open and close operations.

9. Method: Controlling the Gripper using Hand Motions  The Bend Sensor and the Gripper are interfaced using ‘Handy Cricket’.  Cricket runs on PIC16C715 Microcontroller.  Can handle both analog and digital sensor.  Can drive two motors.  Programmed using ‘Cricket Logo’.

10. Method: Controlling the Gripper using Hand Motions  The Handy Cricket is programmed to continuously read the bend sensor data.  If the present reading is lesser than the previous, the gripper is closed.  If the present reading is greater than the previous, the gripper is opened.  This way, the gripper can be controlled using the hand motions of the operator.

11. Method: Delivery of Force Feedback  A Force sensor is placed between the gripper’s tips.  The resistance of the force sensor is maximum when there is no force applied on it.  When the gripper holds a hard object, the resistance of the sensor reduces.

12. Method: Delivery of Force Feedback  The force detected by the sensor is delivered to the user through an electromagnet.  Electromagnet is placed at one of the fingers of the operator.  On the other side of the same finger, a piece of metal/bar magnet is placed.

13. Method: Delivery of Force Feedback  The force sensor is connected to the handy cricket, which is programmed to read the data from the force sensor.  When the value of the sensor is below a certain value (200 in this case) the electromagnet is turned on.  This results in the metal getting attracted by the electromagnet and pressing the operator’s finger.  Thus force feedback is delivered in form of sense of touch(Pinch).

14. Final Setup

15. Problems  The proposed mechanism was to deliver the force feedback through repulsion created between electromagnet and magnet  But: Most of the available electromagnets were designed to attract only. The available repelling electromagnet was very weak.

16. Solution

17. Future Work  Use repelling electromagnets, which can repel a magnet at a distance of about 3 inches  Improve the force sensor to detect a large range of forces  Deliver different levels of feedback, so that the user can identify different materials.

18. Conclusion  The force feedback using electromagnets is a reasonable solution.  This method of haptic feedback can easily be adopted in present day tele-robotic systems with no major design changes

19. Video

20. Questions Thank you for your time and patience. May we answer some Questions Now?