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COMP322/S2000/L121 Workspace Analysis Work Space: Let q min and q max be the vectors in R n denoting the joint variable limits, the set of all values that the joint variables q can assume is called the work space, denoted by Q, i.e., Q = {q R n : q min <= q <= q max }. Work Envelope: The work envelope denoted by P is the locus of all points, p R 3 that are reachable by the tool tip, i.e. P = {p(q) R 3 : q Q }. If P = { [p 1 (q), p 2 (q), p 3 (q) ] T : q Q }, p 1 (q), p 2 (q) define the horizontal reach; and p 3 (q) defines the vertical reach.
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COMP322/S2000/L122 Work Space Fixtures Idea is to present a part (or work material) to the robot at a pre- determined position so that the robot always reaches to the same position to pick up the part. Part Feeders: vibratory bowl (electrically activated), gravity feed. Transport Devices: Conveyors, carousels Fixed Tools: part holding Examples: (refer to class notes)
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COMP322/S2000/L123 Pick-and-Place Operation Pick robot approach the “pick” position with speed (?) “grasp” the object (where to grasp?) with speed (?) “lift” the object with speed (?) Place what path of motion? Obstacle (?) robot approach the “place” position with speed (?) “set-down” the object with speed (?) Example: refer to class notes
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COMP322/S2000/L124 Task Level Programming Task Planning concerns with goals of the manipulation tasks. Three methods of task level programming: 1. By guiding 2. By an explicit robot-level programming language 3. By specifying a task-level sequence of states (or operations) Comparable to programming languages: 1. Binary code, assembly language 2. FORTRAN, C, etc. 3. Object Oriented, query type.
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COMP322/S2000/L125 Task Level Programming Programming by guiding: (or teach pendant method) example: Motoman writing a Chinese character (lab-1) this is the earliest and most wide-spread method in industry simple to use and to implement, no need of a general purpose computer while the human operator is “teaching” the robot, it is “out-of- service” parts, objects must be presented at the same position and orientation each time open-loop approach, difficult to incorporate external sensors adequate for spot welding, painting and simple material handling tasks
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COMP322/S2000/L126 Task Level Programming Programming by an explicit robot-level computer language: example: SONY SRX robot (lab-2) key advantages: allows input data from external sensors so as to control the motions of the robot; more flexible; can program the robot off-line key drawbacks: requires programming skills and design of sensor-based motion strategies can be complicated even with simple task, e.g. pick-and-place operations (LAB-2) knowledge of robot kinematics and positions of movement is needed
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COMP322/S2000/L127 Task Level Programming Programming by specifying a task level sequence of states or operations: completely robot independent actions are specified only by the “goals” and “actions” requires complete geometric models of the environment and robot as input, i.e. descriptions of objects to be manipulated, the robot characteristics, the initial and final states. usually, the task planner will “transform” the specifications to the robot program no commercially available task level programming systems most working systems are in labs and specific to certain types of robots
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