Acoustic contact sensors

1. A computer-implemented method comprising:

causing a transducer to transmit a first acoustic input signal and a second acoustic input signal into a member of a robotic device, wherein the first acoustic input signal is different from the second acoustic input signal;

receiving, from a first receiver, a first electrical detection signal representing reverberations of the first acoustic input signal traveling within the member as received at a first location along the member;

receiving, from the first receiver, a second electrical detection signal representing reverberations of the second acoustic input signal traveling within the member as received at the first location along the member;

detecting a contact of the member with an object external to the member based on a change in at least one of the first electrical detection signal or the second electrical detection signal;

determining, based on the first electrical detection signal, a position along the member of a point of the contact of the member with the object; and

determining, based on the second electrical detection signal, a contact pressure of the contact of the member with the object.

2. The method of claim 1 , further comprising controlling an actuator to maneuver the member in response to the contact.

3. The method of claim 1 , further comprising generating a power spectrum of the at least one of the first electrical detection signal or the second electrical detection signal.

4. The method of claim 1 , wherein determining the position along the member of a point of the contact comprises determining the position based on a change in a power of the first electrical detection signal at a frequency.

5. The method of claim 1 , wherein the second acoustic input signal is a white noise signal.

6. The method of claim 1 , further comprising controlling an actuator to maneuver the member in response determining the contact pressure.

7. The method of claim 1 , further comprising receiving, from a second receiver, a third electrical detection signal representing reverberations of the first acoustic input signal traveling within the member as received at a second location along the member;

wherein determining the position along the member of the point of the contact of the member with the object comprises determining the point of the contact based on both the first electrical detection signal and the third electrical detection signal.

8. The method of claim 1 , wherein the first acoustic input signal is a set of tones calibrated to produce a detection signal with a generally flat power spectrum in the member when an object is not in contact with the member.

9. The method of claim 7 , wherein determining the position along the member of the point of the contact of the member with the object comprises analyzing the first electrical detection signal and the third electrical detection signal with a machine learning model to determine the position along the member of the point of the contact of the member with the object.

10. A robotic device comprising:

a transducer acoustically coupled to an acoustically conductive member of the robotic device;

a first receiver acoustically coupled to the acoustically conductive member of the robotic device at a first location along the member;

an actuator coupled to the member of the robotic device; and

a control system coupled to the transducer, the first receiver, and the actuator, the control system comprising one or more processors and a data store coupled to the one or more processors having instructions stored thereon which, when executed by the one or more processors, causes the one or more processors to perform operations comprising:

controlling the transducer to transmit a first acoustic input signal and a second acoustic input signal into the member, wherein the first acoustic input signal is different from the second acoustic input signal;

receiving, from the first receiver, a first electrical detection signal representing reverberations of the first acoustic input signal traveling within the member as received at the first location;

receiving, from the first receiver, a second electrical detection signal representing reverberations of the second acoustic input signal traveling within the member as received at the first location along the member;

detecting a contact of the member with an object external to the member based on a change in at least one of the first electrical detection signal or the second electrical detection signal;

determining, based on the first electrical detection signal, a position along the member of a point of the contact of the member with the object;

determining, based on the second electrical detection signal, a contact pressure of the contact of the member with the object; and

controlling the actuator to maneuver the member in response to detecting the contact pressure of the contact of the member with the object.

11. The device of claim 10 , wherein the second acoustic input signal is a white noise signal.

12. The device of claim 10 , wherein detecting the contact of the member with the object external to the member comprises analyzing the at least one of the first detection electrical signal or the second electrical detection signal with a machine learning model to detect the contact of the member with the object external to the member.

13. The device of claim 10 , wherein the transducer comprises a transducer and a receiver.

14. The device of claim 13 , wherein the transducer and the receiver are both acoustically coupled to the member.

15. The device of claim 10 , wherein the transducer comprises a piezoelectric transceiver.

16. A non-transitory computer readable storage medium storing instructions that, when executed by at least one processor, cause the at least one processor to perform operations comprising:

causing a transducer to transmit a first acoustic input signal and a second acoustic input signal into a member of a robotic device, wherein the first acoustic input signal is different from the second acoustic input signal;

receiving, from a first receiver, a first electrical detection signal representing reverberations of the first acoustic input signal traveling within the member as received at a first location along the member;

receiving, from the first receiver, a second electrical detection signal representing reverberations of the second acoustic input signal traveling within the member as received at the first location along the member;

detecting a contact of the member with an object external to the member based on a change in at least one of the first electrical detection signal or the second electrical detection signal;

determining, based on the first electrical detection signal, a position along the member of a point of the contact of the member with the object; and

determining, based on the second electrical detection signal, a contact pressure of the contact of the member with the object.

17. The medium of claim 16 , further comprising controlling an actuator to maneuver the member in response to the contact.

18. The medium of claim 16 , further comprising generating a power spectrum of the at least one of the first electrical detection signal or the second electrical detection signal.

19. The medium of claim 16 , wherein determining the position along the member of a point of the contact comprises determining the position based on a change in a power of the first electrical detection signal at a frequency.

20. The medium of claim 16 , wherein the second acoustic input signal is a white noise signal.

21. The medium of claim 16 , further comprising controlling an actuator to maneuver the member in response determining the contact pressure.

22. The medium of claim 16 , further comprising receiving, from a second receiver, a third electrical detection signal representing reverberations of the first acoustic input signal traveling within the member as received at a second location along the member;

wherein determining the position along the member of the point of the contact of the member with the object comprises determining the point of the contact based on both the first electrical detection signal and the third electrical detection signal.

23. The medium of claim 16 , wherein the first acoustic input signal is a set of tones calibrated to produce a detection signal with a generally flat power spectrum in the member when an object is not in contact with the member.