Compliance correction in a robotic system

A method for controlling movement of an object at a sampling frequency, the method comprising:

• Retrieving, by a controller comprising a processor, a trajectory of the object attached to a manipulator of a robotic system controlled by the processor, wherein the trajectory is a path between a first location in space to a second location in space;
• Sampling, by the controller, a primary sensor to receive position and orientation data of the primary sensor in a coordinate system at a time, wherein the primary sensor is positioned at a first location on the object and is configured to record the position and orientation data, wherein the position and orientation data of the primary sensor includes mechanical compliance error;
• Sampling, by the controller, at least one ancillary sensor to receive position and orientation data of the at least one ancillary sensor in the coordinate system at the time, wherein each of the at least one ancillary sensor is positioned at a unique second location on the object and configured to record position and orientation data, wherein the at least one position and orientation data of the at least one ancillary sensor comprises less mechanical compliance error than the position and orientation data of the primary sensor;
• Determining, by the controller, a delta value representing an amount of deviation between an initial static position and orientation of the primary sensor and an estimated position and orientation of the primary sensor at the time based on the position and orientation data of the primary sensor at the time, the position and orientation data of the at least one ancillary sensor at the time, and a static relationship between the primary sensor and the at least one ancillary sensor;
• and
• Modifying, by the controller, execution of the trajectory of the object until a next time that the processor executes the instructions based on the sampling frequency to correct for compliance in the robotic system, the manipulator, and/or the object based on the delta value, the position and orientation data of the primary sensor at the time, and a static relationship between the initial static position and orientation of the primary sensor and an initial static position and orientation of a point on the object, wherein the object is moved along the trajectory with the modified execution until a new modified execution of the trajectory is determined at the next time.

A system comprising:

• an object attached to a manipulator of a robotic system and configured to be moved along a trajectory, wherein the trajectory is a path between a first location in space and a second location in space;
• a primary sensor positioned at a first location on the object and configured to record position and orientation data;
• at least one ancillary sensor, each positioned at a unique second location on the object and configured to record position and orientation data;
• and
• a controller comprising:
• a non-transitory memory storing executable instructions;
• and
• a processor executing the instructions to, at a sampling frequency:
• retrieve the trajectory of the object;
• when the object is at a point on the trajectory at a time:
• sample the primary sensor to receive the position and orientation data of the primary sensor in a coordinate system at the time;
• sample the at least one ancillary sensor to receive position and orientation data of the at least one ancillary sensor in the coordinate system at the time;
• determine a delta value representing an amount of deviation between an initial static position and orientation of the primary sensor and an estimated position and orientation of the primary sensor at the time, wherein the amount of deviation is based on the position and orientation data of the primary sensor at the time, the position and orientation data of the at least one ancillary sensor at the time, and a static relationship between the primary sensor and the at least one ancillary sensor;
• and
• modify execution of the trajectory of the object until a next time that the processor executes the instructions based on the sampling frequency to correct for compliance in the robotic system, the manipulator, and/or the object based on the delta value, the position and orientation data of the primary sensor at the time, and a static relationship between the initial static position and orientation of the primary sensor and an initial static position and orientation of a point on the object, wherein the object is moved along the trajectory with the modified execution until a new modified execution of the trajectory is determined at the next time.