A Flexible and Safe Versatility Associate * - PowerPoint PPT Presentation

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A Flexible and Safe Versatility Associate *

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A Flexible and Safe Versatility Associate *

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  1. Special Topics in Robotics Design and Control of Devices for Human-Movement Assistance A Versatile and Safe Mobility Assistant* Article review Kim, Min-Jung 2001/6/12 *A. Lankenau and T. Rofer, IEEE Robotics & Automation Magazine, March, 2001, pp. 29~37

  2. Bremen Autonomous Wheelchair project • Covers mainly • Spatial cognition • Safe system • Mobility assistant for the handicapped • Implements • Obstacle avoidance + Driving and routing assistant in a shared-control system

  3. Principle idea • A shared-control system • The wheelchair changes the dangerous target command into a safe one.

  4. Safety Layer (1/4) • Local Obstacle Map • A quadratic array of cells, each of which encodes the presence of an obstacle at the corresponding position in the environment of the wheelchair • The wheelchair’s current rotational deviation to the map is continuously updated

  5. Safety Layer (2/4) • Adaptive Sonar Firing Strategy • 27 ultrasonic sensors • Can only fire 2 of its 27 sensors simultaneously. It involves the risk of overlooking relevant obstacles.  Firing strategy is needed

  6. Safety Layer (3/4) • Adaptive Sonar Firing Strategy • Determine the firing sequence from • The wheelchair’s current movement direction, steering angle, and the data represented in the map The adaptive static firing strategy A static firing strategy

  7. Safety Layer (4/4) • Stopping in time • The following things must be considered • The wheelchair’s deceleration and its reaction time • The travel distance to the closest obstacle

  8. Elementary skills (1/3) • Smooth speed control • Early detection of obstacles can make the wheelchair decelerate in a smooth manner • The user can concentrate on steering

  9. Elementary skills (2/3) • Obstacle avoidance • The assistive system infers the will of the user whether the user moves to right or left and reinforce the trend

  10. Elementary skills (3/3) • Turning around • Wheelchair turning is difficult because of the kinematical restriction • It resembles the problem of parking a car • Automatic turning is needed

  11. The mobility assistant • The driving assistant • It combines above three elementary skills for the users to concentrate on steering • The route assistant • The large scale navigation is done by it especially for the users who have amnesia* *amnesia: Partial or total loss of memory, usually resulting from shock, psychological disturbance, brain injury, or illness

  12. Conclusion • The Bremen Autonomous Wheelchair is designed for the handicapped in a shared-control manner • Implemented safety layer and elementary skills for the user’s safe and comfortable navigation