4 Using 3D Hall Sensor for Detecting Collision Angle in Vacuum Robot

If the system is correlating the motion of magnet with the motion of bumper, when the bumper collides with an object then the collision angle can be extrapolated by using a 3D Hall-effect sensor. As shown in Figure 4-1, a magnet is mounted on a frame that is connected to the bumper. When bumper moves, the magnet movement follows due to the connected frame. Although the magnet and hall sensor are placed on the central axis in image, the magnet and Hall sensor can be placed anywhere on the frame because the motion at any point on the frame would be the same.

When a collision occurs from 0⁰~180⁰, the magnets position over the hall sensor would follow a similar path in 3D space path as shown in yellow trace on Figure 4-2. If a 3D linear hall sensor, like TMAG5170, is placed under magnet Figure 4-3 shows the waveform collected by this event. Note that the waveform shape is depended on hall sensor, mounting setup, direction, and the magnets direction.

The bumper is connected with main structure of vacuum robot via a spring. As shown in Figure 4-4, the spring is indicated by the red cylinder under the magnet frame. The spring function is used to return the magnet back into its resting position after a collision occurs. Besides the spring, the chassis should have another structure that helps support the magnetic frame.