System and method for robotic accuracy improvement
View Patent ↗A system and method for sensing and compensating for unintended joint movement of a robotic arm caused by application of a load. The system may have a plurality of external encoders each in intimate contact with an external edge portion of one of a plurality of robotic arm joints to sense joint movement caused by application of the load, and a computing device configured for calculating a compensation amount based on the sensed joint movement and sending the calculated compensation amount to a corresponding robot motor encoder to correct the position of the joint by the compensation amount. The method may comprise applying the load one portion at a time, such that a portion of the load is applied, the compensation amount is calculated, the position of the joint is corrected, and then the process repeats, with another portion of the load applied to the robotic arm.
1. A system for sensing and correcting unintended movement of a first joint of a robotic arm, wherein the robotic arm comprises a plurality of sections including an end effector, a plurality of joints at which the plurality of sections interconnect with each other, and a plurality of robot motor encoders, each for actuating physical movement of at least one of the sections of the robotic arm at one of the joints, wherein the first joint is coupled to a first robot motor encoder for actuating physical movement of the first joint, the system comprising:
a first external encoder in intimate physical contact with an external portion of the first joint and configured to sense pivotal movement of the first joint and to transmit a first data signal corresponding to an amount of pivotal movement sensed by the first external encoder;
a computing device configured for:
receiving the first data signal from the first external encoder,
determining a first compensation amount corresponding to the amount of pivotal movement sensed by the first external encoder, and
communicating the first compensation amount to the first robot motor encoder to actuate the first joint by an amount corresponding to the first compensation amount; and
an attachment apparatus configured to hold an intermediate wheel in intimate contact with the first joint on one side of the intermediate wheel and in intimate contact with the first external encoder on another side of the intermediate wheel, creating a gear reduction between the first external encoder and the first robot motor encoder, the attachment apparatus further comprising:
a first arm rotatably attached to the intermediate wheel and fixedly attached to one of the plurality of sections of the robotic arm; and
a second arm rotatably attached to the first arm and rotatably attached to the first external encoder, the second arm being configured to bias a wheel portion of the first encoder against the intermediate wheel.
2. The system of claim 1 , wherein the amount of pivotal movement sensed by the first external encoder is relative to an initial position value obtained prior to an application of a load on the robotic arm.
3. The system of claim 1 , wherein the second arm biases the first encoder against the intermediate wheel using a spring attached to the first arm and the second arm.
4. The system of claim 1 , further comprising:
a second external encoder in intimate physical contact with an external portion of a second joint and configured to sense pivotal movement of the second joint and to transmit a second data signal corresponding to an amount of pivotal movement sensed by the second external encoder,
wherein the computing device is configured for:
receiving the second data signal from the second external encoder,
determining a second compensation amount corresponding to the amount of pivotal movement sensed by the second external encoder, and
communicating the second compensation amount to the second robot motor encoder to actuate the second joint by an amount corresponding to the second compensation amount.