Collision avoidance during teleoperation using whole arm proximity sensors coupled to a virtual environment
Much of the current robotics effort at the US DOE is directed toward remote handling of hazardous waste. Telerobotic systems are being developed to remotely inspect, characterize, and process waste. This paper describes a collision avoidance system using Whole Arm Proximity (WHAP) sensors on an articulated robot arm. The capacitance-based sensors generate electric fields which completely encompass the robot arm and detect obstacles as they approach from any direction. The robot is moved through the workspace using a velocity command generated either by an operator through a force-sensing input device or a preprogrammed sequence of motions. The directional obstacle information gathered by the WHAP sensors is then used in a matrix column maximization algorithm that automatically selects the sensor closest to an obstacle during each robot controller cycle. The distance from this sensor to the obstacle is used to reduce the component of the command input velocity along the normal axis of the sensor, allowing graceful perturbation of the velocity command to prevent a collision. By scaling only the component of the velocity vector in the direction of the nearest obstacle, the control system restricts motion in the direction of an obstacle while permitting unconstrained motion in other directions. The actual robot joint positions and the WHAP sensor readings are communicated to an operator interface consisting of a graphical model of the Puma robot and its environment. Circles are placed on the graphical robot surface at positions corresponding to the locations of the WHAP sensor. As the individual sensors detect obstacles, the associated circles change color, providing the operator with visual feedback as to the location and relative size of the obstacle. At the same time, the graphical robot position is updated to reflect the actual state of the robot. This information permits the operator to plan alternative paths around unmodeled, but sensed, obstacles.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10183289
- Report Number(s):
- SAND-93-1889C; CONF-9309199-4; ON: DE93019434; TRN: 93:021666
- Resource Relation:
- Conference: Society of Photo-Optical Instrumentation Engineer`s (SPIE) international symposium on optical tools for manufacturing and advanced automation,Boston, MA (United States),7-10 Sep 1993; Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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