Photograph of PUMA test rig setup

 

 

For multiple targets in view, the system uses a ‘Winner-Take-All’ surface to determine the most salient item. The co-ordinates of this are then fed to the robot movement controller, which outputs the movements required to move the robotic arm head from its present position to the viewed position of the target. The Active Interpolated Surface then adds an adjustment to these required movements to take the conveyor speed and time of movement for the robotic arm into account. The surface is self-correcting, quickly learning the parameters of the system from no initial knowledge in order to achieve success.

This Webot simulation depicts the robotic arm about to remove a target. Although the conveyor did not move in this simulation, it can be used if combined with the properties of the actual arm, to ensure that the generator of the required movement for robotic arm movement to the visual target position is correct.

The velocity map for the robot arm movement is shown in the image below. This non-linear profile, from the PUMA documentation, was used to calculate the movement time for the robotic arm. The surface had to change to predict the effect of this non-linear movement time combined with the conveyor speed and thus adjust the target position for the robotic arm. The surface is self adjusting neither requiring nor pre-programmed with movement equations for the robotic arm or conveyor speed. The equations are used to simulate the dynamic positions of the targets over time.

This animation below shows the shape of the surface after each of the first 11 successful moves of the robotic arm. Only successful moves remain permanent on the surface, thus although the robotic arm will almost certainly have made 40 moves in total in this time, unsuccessful moves help only to temporarily shape the surface for the next move, and thus do not aid the overall development of the surface. The final image in the series depicts the surface after 1000 moves, and although different, it is clear the majority of the shaping is carried out in the initial moves.