Ground compaction roller with sensor device on the roller drum, and method for ascertaining the ground stiffness

A method for ascertaining ground stiffness during ground compaction with a ground compaction roller, wherein the ground compaction roller comprises

• a machine frame;
• a drive unit;
• at least one roller drum mounted on the machine frame for rotation about a rotation axis;
• an exciter device arranged at least partially in the roller drum;
• at least one sensor device configured to measure compaction of ground achieved by passage of the ground compaction roller;
• wherein the sensor device is arranged on the roller drum in a region of the rotation axis and rotates together with the roller drum during operation of the ground compaction roller;
• wherein the sensor device includes an electrical power supply which is independent of an on-board grid of the ground compaction roller;
• wherein the sensor device is supplied with electrical power through a generator driven by an exciter shaft of the exciter device;
• and
• wherein the method comprises:
• a) measuring acceleration directly on, and in a region of the rotation axis of, the roller drum which rotates in working operation;
• b) ascertaining the ground stiffness from the measured acceleration;
• and
• c) wirelessly transmitting the measured acceleration and/or the ground stiffness to a receiving device.