Robot having multiple degrees of freedom

A method of processing workpieces to produce a product, comprising:

• positioning a plurality of generally parallel workpieces in one or more cassettes, the cassettes being located within the scope of action of a robotic arm capable of R, .theta., Z and at least one of Y, E and J motions, the cassettes having axes which are not coplanar with a primary axis of the robotic arm;
• selectively independently rotating the end effector about at least one of a Y roll and pitch axes;
• monitoring the R, .theta. and Z positions of the arm and at least one of the Y, E and J positions of a wrist portion of the arm;
• controlling the R, .theta. and Z positions of the arm and one or more of the Y, E and J positions of the wrist portion of the arm;
• measuring the alignments of each workpiece as it is to be picked up by the arm;
• controlling the arm so that each workpiece is picked up and delivered in proper alignment for processing;
• processing the workpieces to produce the product;
• and
• recovering the product.

A method for controlling a robotic arm structure utilizing electronic computer means, the arm structure having a radial drive shaft and a rotary drive shaft respectively providing R- and .theta. motion and having an end effector drive shaft providing Y (yaw) motion, each drive shaft being driven by a respective motor, the arm structure having n longitudinally extending links, each link having respective proximal and distal end portions, n being 2 or a larger integer, and an end effector mounted at a distal end portion of an outermost of the links, comprising the steps of:

• repeatedly measuring the rotational positions of the radial drive shaft, the rotary drive shaft and the end effector drive shaft;
• generating electronic signals representative of the rotational positions;
• communicating the electronic signals representative of the rotational positions to the electronic compute means;
• utilizing the electronic computer means to compute the locus of the end effector from the electronic signals representative of the rotational positions of the drive shafts, and to control the drive motors to move and position the end effector in any desired location within its reach;
• wherein the step of utilizing comprises the substeps of:
• continuously generating the desired position, orientation, velocity, acceleration and jerks of the end effector;
• continuously measuring the motor positions;
• solving a direct kinematic problem at position level by calculating the position and the orientation of the end effector, and an end effector tracking error;
• calculating the current end effector path;
• generating a velocity profile of the end effector;
• calculating an end effector velocity vector;
• solving an inverse of the kinematic problem at velocity level;
• transforming joint velocities into motor velocities;
• and
• communicating the motor velocities to the motors.

In an arm structure providing .theta.-, R- and Z-motion which includes at least two links, each having a proximalmost end portion and a distalmost end portion, with the .theta. motion being about a primary axis at the proximal end portion of a proximalmost of the links, R motion proceeding radially from the primary axis whereby the distal end portion of a distalmost of the links can be moved in arbitrary continuous paths including multisegment smooth trajectories and straight lines and an end effector having an end effector portion thereof pivotally mounted for rotation relative to the distal end portion of the distalmost link about an end effector axis which is parallel to the primary axis, the improvement comprising:

• a motor mounted to a respective one of the distalmost link and the end effector, the motor being connected to drive relative rotation about the end effector axis between the distal end portion of the distalmost link and the end effector portion and to thereby provide a yaw (Y) motion;
• sensor means for sensing the R, .theta., Z and Y motions and for creating electronic signals representative thereof;
• signal transmission means for delivering the electronic signals to the computer means;
• electronic computer means for monitoring and controlling the R, .theta., Z and Y motions, the electronic computer means including means for monitoring and controlling the Y-motion such that the end effector can be moved in a straight line which is not restricted to the radial direction.

A robotic arm mechanism adapted to manipulate workpieces which provides R, .theta. and Y (yaw) motion, comprising:

• two pairs of linkages, each linkage having a proximal link having proximal and distal end portions and a distal link having proximal and distal end portions, the distal end portion of the distal link of each of the pairs of linkages being pivotally mounted at a distal axis to one another, the distal end portion of each proximal link being pivotally mounted to the proximal end portion of the corresponding distal link at a respective elbow axis, the proximal end portion of each proximal link being pivotally mounted at a respective shoulder axis to a relatively static support and in spaced apart relation to one another;
• an end effector mounted at the distal end portion of the distal links for pivotal motion about the distal axis, all of the pivotal axes being parallel to one another and extending in a first direction, the links and the end effector being spaced from one another along the direction of the axes such that the links can be moved orthogonally to the first direction in a volume extending along the first direction without obstruction from one another;
• a yaw motor connected to drive relative rotation of the end effector about the distal axis;
• an elbow motor connected to drive relative rotation between the proximal end portion of a respective one of the distal links and the distal end portion of the corresponding proximal link;
• and
• a shoulder motor connected to drive rotation of the proximal end portion of one of the proximal links relative to the static structure.

In a robotic arm structure having .theta.-, R- and Z-motors for providing .theta.-, R- and Z-motions about a primary axis, the arm structure having an end effector portion thereof pivotally mounted for rotation about an end effector axis which is parallel to the primary axis, the arm structure being controlled by electronic computer means controlling the .theta.-, R- and Z-motors and thereby the corresponding motions, sensor means for sensing the R, .theta.- and Z-motions and for creating electronic signals representative thereof and signal transmission means for delivering the electronic signals to the computer means, the improvement comprising:

• means for providing yaw (Y) and roll (E) motion of the end effector;
• workpiece orientation determining means for determining the orientation of a workpiece which is to be picked up by the end effector and for creating an error electronic signal representative thereof;
• means for transmitting the error signal to the computer means;
• wherein the computer means includes means for computing corrections to be applied to the R, .theta., Z, Y and E motions such that the workpiece can be picked up and transported by the end effector in a desired orientation.

In a robotic arm structure having .theta.-, R- and Z-motors for providing .theta.-, R- and Z-motions about a primary axis, the arm structure having an end effector portion thereof pivotally mounted for rotation about an end effector axis which is parallel to the primary axis, the arm structure being controlled by electronic computer means controlling the .theta.-, R- and Z-motors and thereby the corresponding motions, sensor means for sensing the R, .theta.- and Z-motions and for creating electronic signals representative thereof and signal transmission means for delivering the electronic signals to the computer means, the improvement comprising:

• an elevator moveable along the Z axis, the robotic arm structure being supported by the elevator;
• means for controllably tilting the elevator about any axis lying in a plane orthogonal to the Z axis;
• means for providing at least one of yaw (Y), roll (E), and pitch (J) motion of the end effector;
• workpiece orientation determining means for determining the orientation of a workpiece which is to be picked up by the end effector and for creating an error electronic signal representative thereof;
• means for transmitting the error signal to the computer means;
• wherein the computer means includes means for computing corrections to be applied to control the tilting of the elevator, to the R, .theta. and Z motions and to one or more of the Y, E J motions such that the workpiece can be picked up and transported by the end effector in a desired orientation.

In a robotic arm structure having .theta.-, R- and Z-motors for providing .theta.-, R-and Z-motions about a primary axis, the arm structure having an end effector portion thereof pivotally mounted for rotation about an end effector axis which is parallel to the primary axis, the arm structure being controlled by electronic computer means controlling the .theta.-, R- and Z-motors and thereby the corresponding motions, sensor means for sensing the R, .theta.- and Z-motions and for creating electronic signals representative thereof and signal transmission means for delivering the electronic signals to the computer means, the improvement enabling picking up and transporting workpieces in cassettes located in a planar region generally parallel to the Z axis, comprising:

• means for providing yaw (Y) and pitch (J) motion of the end effector;
• workpiece orientation determining means for determining the orientation of a workpiece which is to be picked up by the end effector and for creating an electronic signal representative thereof;
• means for transmitting the signal to the computer means;
• wherein the computer means includes means for computing corrections to be applied to control the R, .theta., Z, Y and J motions such that the workpiece can be picked up and transported by the end effector in a desired orientation.