13 ‐ 10 ‐ 2017 UNIT ‐ V Prepared by Dr.K.S.Badrinathan 1 IMPLEMENTATION AND ROBOT ECONOMICS • Automated Guided Vehicle System (AGVS), RGV • Implementation of Robots in Industries • Safety Considerations for Robot Operations • Economic Analysis of Robots. Prepared by Dr.K.S.Badrinathan 2 1
13 ‐ 10 ‐ 2017 Automated Guided Vehicle System (AGVS) • An AGVS is a material handling system that uses independently operated, self ‐ propelled vehicles guided along defined pathways. • Powered by on ‐ board batteries that allow many hours of operation (8 ‐ 16 hours) • Pathways are unobtrusive. • Suitable for automating material handling in batch production & mixed model production Prepared by Dr.K.S.Badrinathan 3 Types of AGV vehicles • Driverless trains • Pallet trucks • Unit load carriers Prepared by Dr.K.S.Badrinathan 4 2
13 ‐ 10 ‐ 2017 Driverless AG train Prepared by Dr.K.S.Badrinathan 5 Driverless AG train • A towing vehicle pulling one or more trailers to form a train • To move heavy payloads over long distances in warehouses or factories with or without intermediate pickup and drop ‐ off points along the route Prepared by Dr.K.S.Badrinathan 6 3
13 ‐ 10 ‐ 2017 Pallet Trucks Prepared by Dr.K.S.Badrinathan 7 Pallet trucks • To move palletized loads along predetermined routes • Human worker steers the truck and loads the pallet & puts it in is guidepath • Forklift AGV – can have vertical movement of its forks to reach loads on racks and shelves Prepared by Dr.K.S.Badrinathan 8 4
13 ‐ 10 ‐ 2017 Unit Load Carriers Prepared by Dr.K.S.Badrinathan 9 Unit Load Carrier • To move unit loads from one station to another • Equipped for automatic loading and unloading of pallets or tote pans by means of : – Powered rollers – Moving belts – Mechanized lift platforms – Other devices built into the vehicle deck Prepared by Dr.K.S.Badrinathan 10 5
13 ‐ 10 ‐ 2017 Applications of AGVS • Driverless train operations • Storage and distribution • Assembly line applications • FMS Prepared by Dr.K.S.Badrinathan 11 Vehicle Guidance Technology • Method by which AGVS pathways are defined and vehicles are controlled to follow the pathways Technologies used: • Imbedded guide wires • Paint strips • Self ‐ guided vehicles Prepared by Dr.K.S.Badrinathan 12 6
13 ‐ 10 ‐ 2017 Wire Guided AGV Prepared by Dr.K.S.Badrinathan 13 Wire Guided AGV • Electrical wires are placed in a small channel cut into the surface of the floor • The channel is filled with cement to eliminate the discontinuity in the floor surface • Guide wire is connected to a frequency generator, which emits low ‐ voltage, low ‐ current signal (1 ‐ 15kHz) • The induced magnetic field is followed by sensors on board each vehicle Prepared by Dr.K.S.Badrinathan 14 7
13 ‐ 10 ‐ 2017 Paint Strip AGV Prepared by Dr.K.S.Badrinathan 15 Paint Strip AGV • Vehicle uses an optical sensor system capable of tracking the paint • Strips are taped, sprayed or painted on the floor • Paint strips contain fluorescent particles that reflect an UV light source from the vehicle • On ‐ board sensor detects the reflected light in the strip and controls the steering mechanism Prepared by Dr.K.S.Badrinathan 16 8
13 ‐ 10 ‐ 2017 Self ‐ guided Vehicle Prepared by Dr.K.S.Badrinathan 17 Self ‐ guided Vehicle • Operate without continuously defined pathways • Uses a combination of dead reckoning and beacons located throughout the plant that can be identified by on ‐ board sensors • Dead reckoning: capability of vehicle to follow a given route in the absence of a defined pathway in the floor • Accomplished by computing the required number of wheel rotations • Computations are performed by the vehicle’s on ‐ board computer Prepared by Dr.K.S.Badrinathan 18 9
13 ‐ 10 ‐ 2017 Self ‐ guided Vehicle ‐ Beacons • Positioning accuracy of dead reckoning decreases over long distances. • It must be periodically verified by comparing the calculated position with one or more known positions. • Beacons are used for this throughout the plant • Barcoded or magnetic beacons Prepared by Dr.K.S.Badrinathan 19 RGV Rail Guided Vehicle Prepared by Dr.K.S.Badrinathan 20 10
13 ‐ 10 ‐ 2017 Steps for Robot Implementation • Initial familiarization with the technology • Plant survey to identify potential applications • Selection of the application • Selection of the robot • Detailed economic analysis & capital authorization • Planning and engineering the installation • installation Prepared by Dr.K.S.Badrinathan 21 Human Safety from Robots • During programming of the robot • During operation of the robot cell when humans work in the cell • During maintenance of the robot Prepared by Dr.K.S.Badrinathan 22 11
13 ‐ 10 ‐ 2017 Safety Sensors • Sensors indicate conditions or events that are unsafe or potentially unsafe • Sensors should protect humans and also the equipment in the cell • Simple limit switches to sophisticated vision systems are needed to find intruders • Care must be taken in the workcell design to anticipate all of the possible mishaps that might occur in the cell Prepared by Dr.K.S.Badrinathan 23 Levels of Safety Sensor Systems • Level 1 – Perimeter penetration detection • Level 2 – Intruder detection inside the workcell • Level 3 – Intruder detection in the immediate vicinity of the robot Prepared by Dr.K.S.Badrinathan 24 12
13 ‐ 10 ‐ 2017 Levels of Safety Sensor Systems Prepared by Dr.K.S.Badrinathan 25 Safety Monitoring Strategies • Complete shutdown of the robot upon detection of an intruder • Activation of warning alarms • Reduction in the speed of the robot to a ‘safe’ level • Directing the robot to move its arm away from the intruder to avoid collision • Directing the robot to perform tasks in another region of the workcell away from the intruder Prepared by Dr.K.S.Badrinathan 26 13
13 ‐ 10 ‐ 2017 Other Safety Measures • Emergency stop buttons also called ‘panic button’ are located on the main control panel and the robot teach pendant. • ‘Deadman switch’ – is a trigger or toggle switch device located on the teach pendant. The switch is ‘ON’ when it is pressed against a spring. When the pressure is removed the switch automatically goes to ‘OFF’ mode. Prepared by Dr.K.S.Badrinathan 27 ECONOMIC ANALYSIS of ROBOTS Prepared by Dr.K.S.Badrinathan 28 14
13 ‐ 10 ‐ 2017 Basic Data Required • Type of project • Cost of robot installation • Production cycle time • Savings & Benefits Prepared by Dr.K.S.Badrinathan 29 Types of Robot Installation • New application – no existing facility • To replace the current method of operation; i.e. the manual method is replaced with robot Prepared by Dr.K.S.Badrinathan 30 15
13 ‐ 10 ‐ 2017 Cost Data Required • Investment cost – Cost of robot: purchase price – Engineering cost: planning and design – Installation cost: labour & materials – Special tooling: end effector, fixtures & tools – Miscellaneous: other equipment needed • Operating cost – Direct labour: operator – Indirect labour: supervisor, programming – Maintenance: – Utilities: electricity etc. – Training: Prepared by Dr.K.S.Badrinathan 31 Life cycle of cash flow Prepared by Dr.K.S.Badrinathan 32 16
13 ‐ 10 ‐ 2017 Methods of Economic Analysis • Payback (or payback period) Method • Equivalent Uniform Annual Cost (EUAC) Method • Return On Investment (ROI) Method Prepared by Dr.K.S.Badrinathan 33 Payback Method • Time required for the net accumulated cash flow to equal the initial investment in the project �� n = ���� n = pay back period IC = Investment Cost NACF = Net Annual Cash Flow Prepared by Dr.K.S.Badrinathan 34 17
13 ‐ 10 ‐ 2017 Payback Method… • Total Investment = Rs.30 lacs • Anticipated revenue = Rs.18 lacs/year • Operating cost = Rs.6 lacs/year • NACF = Revenue – operating cost = 18 – 6 = Rs.12 lacs/year ���� = �� �� n = �� = 2.5 years Note: revenue is assumed to be same in all the years Prepared by Dr.K.S.Badrinathan 35 Disadvantage of Payback method • Ignores the time value of money • It does not consider the objective of the company to derive a certain minimum rate of return from its investments. Prepared by Dr.K.S.Badrinathan 36 18
13 ‐ 10 ‐ 2017 Equivalent Uniform Annual Cost (EUAC) Method • Converts all the present and future investments and cash flows into their equivalent uniform cash flows over the anticipated life of the project. • Done by making use of the various interest factors associated with engineering economy calculations. • A minimum attractive rate ‐ of ‐ return (MARR), 20 ‐ 50, should be selected to decide whether a investment project should be funded. Prepared by Dr.K.S.Badrinathan 37 Equivalent Uniform Annual Cost (EUAC) Method • Total Investment = Rs.30 lacs • Anticipated revenue = Rs.18 lacs/year • Operating cost = Rs.6 lacs/year • Service life of robot = 5 years • MARR = 30% • EUAC = ‐ 30,00,000 (A/P,30%,5) +18,00,000 ‐ 6,00,000 = ‐ 30,00,000 (0.41058) + 12,00,000 = ‐ 31,740 Note: if EUAC is positive, then project can be funded Prepared by Dr.K.S.Badrinathan 38 19
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