Compensating for the vibration of the vehicle
View Patent ↗To compensate for the effects of vibration on a lidar system in a vehicle, a vibration sensor within the lidar system and/or the vehicle detects vibration, such as a gyroscope, accelerometer, inertial measurement unit (IMU), etc. The detected vibration is then used to generate a compensation signal. The compensation signal is combined with a drive signal that drives a scanner configured to direct light pulses across a field of regard. The combined signal is provided to the scanner, and accordingly, the light pulses are accurately directed across the field of regard.
1. A method for compensating for vibration in a lidar system, the method comprising:
emitting light pulses by a light source in the lidar system;
generating a drive signal for a scanner in the lidar system to direct the light pulses across a field of regard of the lidar system toward different points within the field of regard;
determining an amount of vibration at the lidar system via an accelerometer, gyroscope, or inertial measurement unit (IMU);
generating a compensation signal that reduces effects of vibration on the scanner based on the determined amount of vibration; and
combining the drive signal for the scanner with the compensation signal.
2. The method of claim 1 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard, and the compensation signal represents an inverse of the offset vertical orientations.
3. The method of claim 2 , wherein the drive signal includes a horizontal drive signal and a vertical drive signal directed via a horizontal scanning mirror and a vertical scanning mirror respectively, and the vertical drive signal drives the vertical scanning mirror at a lower frequency than the horizontal scanning mirror, such that a vertical orientation of the light pulses remains constant across the predetermined horizontal field of regard.
4. The method of claim 1 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined vertical field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset horizontally from the predetermined vertical field of regard, and the compensation signal represents an inverse of the offset horizontal orientations.
5. The method of claim 1 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard and across a predetermined vertical field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard and orientations offset horizontally from the predetermined vertical field of regard, and the compensation signal represents an inverse of a combination of the offset vertical orientations and the offset horizontal orientations.
6. The method of claim 1 , wherein:
the drive signal causes the scanner to direct the light pulses along a first scan direction and along a second scan direction substantially orthogonal to the first scan direction;
the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset along the second scan direction from the first scan direction; and
the compensation signal represents an inverse of the orientations offset along the second scan direction.
7. The method of claim 1 , wherein combining the drive signal for the scanner with the compensation signal comprises adding the compensation signal to the drive signal.
8. The method of claim 1 , wherein:
the scanner comprises one or more scanning mirrors for directing the light pulses across the field of regard and one or more vibration-compensation mirrors; and
combining the drive signal for the scanner with the compensation signal comprises:
applying the drive signal to the one or more scanning mirrors; and
applying the compensation signal to the vibration-compensation mirrors.
9. The method of claim 1 , wherein a vibration signal corresponding to the amount of vibration is analyzed to predict future amounts of vibration, and the compensation signal is applied to reduce the effects of the future amounts of vibration on the scanner.
10. The method of claim 1 , wherein a vibration signal includes damping effects, and future amounts of vibration are predicted based on a damping ratio of the vibration signal.
11. A lidar system comprising:
a light source configured to emit light pulses;
a scanner configured to scan a field of regard of the lidar system including directing the light pulses at different angles toward different points within the field of regard;
a controller configured to drive the scanner to direct the light pulses across the field of regard, including:
generate a drive signal for directing the light pulses across the field of regard;
obtain an indication of an amount of vibration at the lidar system from an accelerometer, gyroscope, or inertial measurement unit (IMU);
generate a compensation signal that reduces effects of vibration on the scanner based on the determined amount of vibration;
combine the drive signal for the scanner with the compensation signal; and
provide the combined signal to the scanner; and
a detector configured to detect light from some of the light pulses scattered by one or more remote targets to generate respective pixels.
12. The lidar system of claim 11 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard, and the compensation signal represents an inverse of the offset vertical orientations.
13. The lidar system of claim 12 , wherein the scanner includes a horizontal scanning mirror and a vertical scanning mirror, the drive signal includes a horizontal drive signal and a vertical drive signal directed via the horizontal scanning mirror and the vertical scanning mirror respectively, and the vertical drive signal drives the vertical scanning mirror at a lower frequency than the horizontal scanning mirror, such that a vertical orientation of the light pulses remains constant across the predetermined horizontal field of regard.
14. The lidar system of claim 11 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard and across a predetermined vertical field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard and orientations offset horizontally from the predetermined vertical field of regard, and the compensation signal represents an inverse of a combination of the offset vertical orientations and the offset horizontal orientations.
15. The lidar system of claim 11 , wherein a vibration signal corresponding to the amount of vibration is analyzed to predict future amounts of vibration, and the compensation signal is applied to reduce effects of the future amounts of vibration on the scanner.
16. The lidar system of claim 11 , wherein a vibration signal includes damping effects, and future amounts of vibration are predicted based on a damping ratio of the vibration signal.
17. An autonomous vehicle comprising:
an inertial measurement unit (IMU) configured to provide a vibration signal corresponding to an amount of vibration at the autonomous vehicle;
one or more components configured to maneuver the autonomous vehicle;
a lidar system configured to detect objects within a threshold distance of the autonomous vehicle, the lidar system including:
a light source configured to emit light pulses;
a scanner configured to scan a field of regard of the lidar system;
a lidar controller configured to drive the scanner to scan the light pulses across the field of regard, including:
generate a drive signal for directing the light pulses across the field of regard;
receive from the IMU the vibration signal corresponding to the amount of vibration at the autonomous vehicle;
generate a compensation signal that reduces effects of vibration on the scanner based on the amount of vibration;
combine the drive signal for the scanner with the compensation signal; and
provide the combined signal to the scanner; and
a detector configured to detect light from some of the light pulses scattered by one or more remote targets to generate respective pixels corresponding to a point cloud representing the field of regard; and
a vehicle controller configured to provide control signals to the one or more components to maneuver the autonomous vehicle in accordance with data from the point cloud.
18. The autonomous vehicle of claim 17 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard, the vibration at the autonomous vehicle causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard, and the compensation signal represents an inverse of the offset vertical orientations.
19. The autonomous vehicle of claim 18 , wherein the scanner includes a horizontal scanning mirror and a vertical scanning mirror, the drive signal includes a horizontal drive signal and a vertical drive signal directed via the horizontal scanning mirror and the vertical scanning mirror respectively, and the vertical drive signal drives the vertical scanning mirror at a lower frequency than the horizontal scanning mirror, such that a vertical orientation of the light pulses remains constant across the predetermined horizontal field of regard.
20. The autonomous vehicle of claim 17 , wherein the drive signal causes the scanner to direct the light pulses across a predetermined horizontal field of regard and across a predetermined vertical field of regard, the vibration at the lidar system causes the scanner to direct the light pulses at orientations offset vertically from the predetermined horizontal field of regard and orientations offset horizontally from the predetermined vertical field of regard, and the compensation signal represents an inverse of a combination of the offset vertical orientations and the offset horizontal orientations.
21. The autonomous vehicle of claim 17 , wherein the vibration signal corresponding to the amount of vibration is analyzed to predict future amounts of vibration, and the compensation signal is applied to reduce effects of the future amounts of vibration on the scanner.
22. The autonomous vehicle of claim 17 , wherein the vibration signal includes damping effects and future amounts of vibration are predicted based on a damping ratio of the vibration signal.