Phantom degrees of freedom in joint estimation and control

A system comprising:

• a mechanical body having a first set of degrees of freedom corresponding to a plurality of joints included in the mechanical body;
• a controller including at least one processor configured to perform operations including:
• estimating a difference between a desired position of a portion of the mechanical body and an actual position of the portion of the mechanical body;
• determining control variables corresponding to a second set of degrees of freedom for the mechanical body by applying a kinematic model to the estimated difference between the desired position of the portion of the mechanical body and the actual position of the portion of the mechanical body, the second set of degrees of freedom including the first set of degrees of freedom and one or more missing degrees of freedom for the portion of the mechanical body, each of the one or more missing degrees of freedom corresponding to a kinematic motion that is missing for the portion of the mechanical body;
• and
• using the control variables corresponding to the first set of degrees of freedom to control movement of the plurality of joints of the mechanical body in accordance with the estimated difference between the desired position of the portion of the mechanical body and the actual position of the portion of the mechanical body.

A computer-readable hardware storage device that stores a computer program for controlling movement of a mechanical body, the computer program including instructions that, when executed by a computer, cause the computer to perform operations comprising:

• estimating a difference between a desired position of a portion of the mechanical body and an actual position of the portion of the mechanical body, the mechanical body having a first set of degrees of freedom corresponding to a plurality of joints included in the mechanical body;
• determining control variables corresponding to a second set of degrees of freedom for the mechanical body by applying a kinematic model to the estimated difference between the desired position of the portion of the mechanical body and the actual position of the portion of the mechanical body, the second set of degrees of freedom including the first set of degrees of freedom and one or more missing degrees of freedom for the portion of the mechanical body, each of the one or more missing degrees of freedom corresponding to a kinematic motion that is missing for the portion of the mechanical body;
• and
• using the control variables corresponding to the first set of degrees of freedom to control movement of the plurality of joints of the mechanical body in accordance with the estimated difference between the desired position of the portion of the mechanical body and the actual position of the portion of the mechanical body.