Grade and slope lockout for extender movement of construction machine

1. A construction machine comprising:

a tractor;

a hopper coupled to the tractor;

an implement coupled to the tractor via at least one tow arm, the implement having an extender;

an acceleration sensor mounted to the implement;

one or more processors configured to perform operations comprising:

determining that the extender is not moving;

in response to determining that the extender is not moving, operating under a first control scheme, wherein operating under the first control scheme includes:

receiving acceleration data from the acceleration sensor;

generating a first estimated slope of the implement based on the acceleration data; and

modifying a slope of the implement based on the first estimated slope by causing movement of the at least one tow arm;

determining that the extender is moving; and

in response to determining that the extender is moving, operating under a second control scheme, wherein operating under the second control scheme includes:

maintaining the slope of the implement substantially constant.

2. The construction machine of claim 1 , wherein:

the construction machine is an asphalt paver;

the implement is a screed;

the extender is a screed extender; and

the acceleration sensor is an accelerometer.

3. The construction machine of claim 1 , wherein maintaining the slope of the implement substantially constant includes locking the at least one tow arm.

4. The construction machine of claim 1 , wherein maintaining the slope of the implement substantially constant includes not receiving new acceleration data from the acceleration sensor.

5. The construction machine of claim 1 , wherein maintaining the slope of the implement substantially constant includes not generating a new estimated slope of the implement.

6. A construction machine comprising:

an implement having an extender;

an acceleration sensor mounted to the implement;

one or more processors configured to perform operations comprising:

operating under a first control scheme, wherein operating under the first control scheme includes:

receiving acceleration data from the acceleration sensor;

generating a first estimated slope of the implement based on the acceleration data; and

modifying a slope of the implement based on the first estimated slope;

determining that the extender is moving; and

in response to determining that the extender is moving, operating under a second control scheme, wherein the second control scheme includes at least one operation that is different than an operation of the first control scheme.

7. The construction machine of claim 6 , wherein the operations further comprise:

determining that the extender is not moving; and

in response to determining that the extender is not moving, operating under the first control scheme.

8. The construction machine of claim 6 , wherein modifying the slope of the implement includes:

causing movement of a tow arm mechanically coupled to the implement so as to modify the slope of the implement.

9. The construction machine of claim 6 , wherein operating under the second control scheme includes:

maintaining the slope of the implement substantially constant.

10. The construction machine of claim 6 , further comprising:

an angular rate sensor mounted to the implement.

11. The construction machine of claim 10 , wherein:

operating under the first control scheme further includes:

receiving first angular rate data from the angular rate sensor mounted to the implement; and

generating the first estimated slope of the implement based on one or both of the acceleration data and the first angular rate data; and

operating under the second control scheme includes:

receiving second angular rate data from the angular rate sensor;

generating a second estimated slope of the implement based on the second angular rate data but not on data received from the acceleration sensor; and

modifying the slope of the implement based on the second estimated slope.

12. The construction machine of claim 6 , wherein determining that the extender is moving includes one or more of:

receiving user input from a user input device to move the extender;

receiving extender data from an extender sensor mounted to the implement indicating that the extender is moving;

determining that an instruction was sent to an extender actuator to move the extender;

receiving a status from the extender actuator that the extender is moving; and

analyzing the acceleration data to determine that the extender is moving.

13. The construction machine of claim 6 , wherein:

the construction machine is an asphalt paver;

the implement is a screed;

the extender is a screed extender;

the acceleration sensor is an accelerometer; and

the angular rate sensor is a gyroscope.

14. A method of controlling an implement of a construction machine, the method comprising:

operating under a first control scheme, wherein operating under the first control scheme includes:

receiving acceleration data from an acceleration sensor mounted to the implement;

generating a first estimated slope of the implement based on the acceleration data; and

modifying a slope of the implement based on the first estimated slope;

determining that an extender of the implement is moving; and

in response to determining that the extender is moving, operating under a second control scheme, wherein the second control scheme includes at least one operation that is different than an operation of the first control scheme.

15. The method of claim 14 , further comprising:

determining that the extender is not moving; and

in response to determining that the extender is not moving, operating under the first control scheme.

16. The method of claim 14 , wherein modifying the slope of the implement includes:

causing movement of a tow arm mechanically coupled to the implement so as to modify the slope of the implement.

17. The method of claim 14 , wherein operating under the second control scheme includes:

maintaining the slope of the implement substantially constant.

18. The method of claim 14 , wherein:

operating under the first control scheme further includes:

receiving first angular rate data from an angular rate sensor mounted to the implement; and

generating the first estimated slope of the implement based on one or both of the acceleration data and the first angular rate data; and

operating under the second control scheme includes:

receiving second angular rate data from the angular rate sensor;

generating a second estimated slope of the implement based on the second angular rate data but not on data received from the acceleration sensor; and

modifying the slope of the implement based on the second estimated slope.

19. The method of claim 14 , wherein determining that the extender is moving includes one or more of:

receiving user input from a user input device to move the extender;

receiving extender data from an extender sensor mounted to the implement indicating that the extender is moving;

determining that an instruction was sent to an extender actuator to move the extender;

receiving a status from the extender actuator that the extender is moving; and

analyzing the acceleration data to determine that the extender is moving.

20. The method of claim 14 , wherein:

the construction machine is an asphalt paver;

the implement is a screed;

the extender is a screed extender;

the acceleration sensor is an accelerometer; and

the angular rate sensor is a gyroscope.