The objective of "TELEMAN 11 - SHERPA" was to develop an advanced robotic device involving new technologies to perform maintenance tasks such as inspection in nuclear environments too hazardous for human intervention. The device was to have special capabilities for negotiating obstacles such as stairs, doorways , etc, and for moving about in cluttered areas of nuclear buildings, where the environmental conditions could combine limited doses of radiation, with heat and other factors.
An advanced robotic device is being developed which incorporates new technologies to perform maintenance tasks such as inspection in nuclear environments too hazardous for human intervention.
The legged robot (SHERPA) has been tested successfully under realistic conditions at 2 nonoperational nuclear power plants. The main results from the research are:
development of an efficient semiautonomous alternating tripod gait (3 legs move at a time, 3 are stationary), to reduce power requirements;
good operator interface such that inexperienced operators soon learn to control the robot (an on board computer controls full coordination of feet trajectories, including reflex actions);
ability to reduce the width of the stance of the robot for narrow openings and it can also step over significant obstacles, climb and descend stairs, rotate, translate and change its overall height;
on board batteries provide power for around 1.5 h operation;
development of a tactile foot with collision and tilt detection and the ability to verify the soundness of the standing surface;
algorithms for position correction, ground clearance and balance such that the load platform (300 kg load) remains horizontal;
development of a specialized test facility to develop the optimum leg decision.
Further tests are underway to define regions where only such a legged machine can operate. These can include many non-nuclear situations, and involve both routine operations (where the floor is not adequate for wheeled/tracked robots) and various accident scenarios.
Work to be done
This project was to cover the legged locomotion sub-system for carrying heavy loads in the environment described above. The originality of the project was to lie in the legged robot's mobility and agility on rough grounds and its greater ability to surmount obstacles, compared with classical wheeled or tracked robots. Improvements to the autonomous behaviour of an existing legged robot were to concern the elimination of the data links and power supply umbilical. To this effect, the robot on-board intelligence was to be expanded by focusing on the development of reflex actions to cope with obstacles. Similarly, power consumption especially for climbing obstacles was to be minimised, through re-analysis of the kinematics and dynamics of the locomotion mechanism, following simulation studies and prototype modelling of this and other legged robots.
It was planned that the legged platform was to undergo on-site testing at nuclear installations of optimised gaits over a range of geometrical obstacles, with a view to defining a future mobile robotic platform with relative compactness, light weight and a power-efficient configuration for extensive maintenance applications in nuclear power plants.
Funding SchemeCSC - Cost-sharing contracts