Manual Robot workshop by Robocrazy www.onlineTPS.com

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Manual Robot workshop conducted by Robocrazy in association with SPRIT India and Total Project Solutions , www.onlineTPS.com

Manual Robot workshop conducted by Robocrazy in association with SPRIT India and Total Project Solutions , www.onlineTPS.com

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  • Full Day Robotics Workshop jerram@irvingisd.net http://www.irvingisd.net/robotics
  • Full Day Robotics Workshop jerram@irvingisd.net http://www.irvingisd.net/robotics
  • Full Day Robotics Workshop jerram@irvingisd.net http://www.irvingisd.net/robotics

Transcript

  • 1. Total Project Solutions E7/83F, Ashoka Society Arera Colony,Bhopal ,462016(M.P.) +91-9826015410/9826050109 +91-755-2420735 www.onlineTPS.com Starting Robotics
  • 2. WIRE CONTROLLED ROBOTS Step ahead towards robotic platform
  • 3.
    • Hobby robots can be easily constructed from
    • Aluminum, steel, tin,
    • Wood, plastic, paper, foam,
    • or a combination of them all
    • Use scrape from
    • Old VCR , CD player, computer parts
    • Toys ,sewing machine store, cycle stores , auto parts
    • Junkyards ………
    Not Hard To Start
  • 4. From Robocrazy BUILDING A ROBOT- PLANNING Would you say someone who plans his future will have a better future?
    • Use fewer and simpler parts!
    • Use off-the-shelf (COMMONLY/READILY AVAILABLE)parts .
    • Use STANDARD materials and equipments.
    • Like:- Do not use more than 2 or 3 different screw/nut -bolts types.
    • YES!
      • Plan in your mind
      • Put it on paper
      • Dimensions, Choice of material, placement of components, drills ,holes
      • EVERYTHING
  • 5. From Robocrazy STEPS INVOLVED IN BUILDING ROBOTS
      • DIMENSIONAL LIMITS OF THE ROBOT
      • CHESSIS OF THE ROBOT
      • MOTORS FOR THE ROBOT
      • POWER TRANSMITION
      • NAVIGATION SYSTEM LIKE WHEELS OR SUBSTITUTE
      • MECHANICS OF THE ROBOT
      • POWER SUPPLY SYSTEM
      • ASSEMBLING
      • TESTING
      • TROUBLE SHOOTING
  • 6. From Robocrazy DIMENSIONAL LIMITS OF THE ROBOT
      • Robots should be such that it is free to move in the work area.
      • In different competitions, ROBOTS should be within the dimensional limits.
      • Dimensions should adapt according to the mobility requirement. e.g.- Racing Cars, micro mouse etc…
      • For lifting robots, dimensions should suite stability under operation
      • Spy robots should be tiny
      • Waste water pipes cleaning robots should adapt to the dia of pipes.
      • Many more tops could be possible
  • 7. First picture : The Body of the Robot
    • The superstructure that holds its electronic and electromechanical components .
    • Robot bodies go by many names, including frame and chassis, but the idea is the same.
  • 8.
    • CHASSIS OF THE ROBOT
      • Shape of Chassis
      • Weight distribution : equal weights must be placed in symmetry
      • most of the cases place load towards centre
      • most of the cases place wheels away from centre
      • perfectly chosen material
      • minimum joints
      • mounting of motors and wheels or castors
  • 9. STRUCTURE OF ROBOT
  • 10.
    • MATERIAL
      • perfect material for a perfect robot
        • like plastic, m.f.r. sheets,synthetic thermocol should be used for floating robots.(softdrinks bottles)
        • light and strong material for flying robots. e.g.- balsa wood ,aluminium,m.f.r. sheets,synthetic thermocol etc.
        • go for easily available iron ,tin sheets for land rovers
        • use commen sense
  • 11.  
  • 12.  
  • 13.
    • WEIGHT OF THE MATERIAL
      • Optimum Weight (key factor)
      • The parts of a robot that contribute the most to its weight are the following, in (typical) descending order:
      • • Batteries
      • • Drive motors
      • • Frame
        • Like flying robots should be light weight.
        • Floating robots material should have low density
        • Sumo bots should be (comparatively) heavy and stable
        • Racing robots should be light (most cases)
  • 14. Motors
  • 15.
    • MOTOR OF THE ROBOT
    • SELECTION OF MOTOR SHOULD BE BASED ON
      • power requirement
      • speed requirement
      • type of drive (4 wheel,2 wheel ……..)
      • load of the material
      • torque requirement
      • Ease of controlling (D.C.,STEPPER,SERVO ETC.)
      • hub of wheel according to diameter of the shaft
  • 16.
    • Reviewing DC Motor Ratings
    • DC motors can be operated at voltages above and below specified rating. the motor rated for 12 V, will run at 6 V, but at reduced speed and torque. Conversely, if the motor is run at 18 to 24 V,the motor will turn faster and will have increased torque.
    • DC motors draw the most current when they are stalled.
    • DC motor is usually too fast to be directly applied in a robot. Gear reduction is necessary to slow down the speed of the shaft it has the positive side effect of increasing torque.
  • 17.  
  • 18.
    • Motor Drives : Navigation System
    CENTERLINE DRIVE MOTOR MOUNT
  • 19.
    • A benefit of centerline mounting is that the robot has no “front” or “back,” at least as far as the drive system is concerned. Therefore, you can create a kind of multidirectional robot that can move forward and backward with the same ease. Of course, this approach also complicates the sensor arrangement of your robot
  • 20.  
  • 21.
    • CAR-TYPE
  • 22.
    • TRICYCLE
  • 23.  
  • 24. Four Wheel Drives biggest drawbacks of the differentially steered robot is that the robot will veer off course ,if one motor is even a wee bit slow.
  • 25.
    • DIFFERENTIAL
    • The technique is exactly the same as steering a military tank: one side of wheels or treads stops or reverses direction while the other side keeps going. The result is that the robot turns in the direction of the stopped or reversed wheel or tread. Because of friction effects, differential steering is most practical with two-wheel-drive systems. Additional sets of wheels, as well as rubber treads, can increase friction during steering
  • 26. GEARING RATIO
    • The gearing ratio is the value at which you change velocity and torque.
    • Achieving a Particular Gearing Ratio If you want a simple gearing ratio of say 2 to 1, you would use two gears, one being twice as big as the other.
    • For a much more accurate calculate the ratio of teeth.
    • (This is why worm gears have such high gearing ratios. In a worm gear setup, one gear always has a single tooth, while the other has many - a guaranteed huge ratio. )
  • 27. NAVIGATION SYSTEM LIKE WHEELS OR SUBSTITUTES (LEGS,PROPELLERS )
  • 28.  
  • 29.
    • Wheel diameter .
      • Large diameter wheels give your robot low torque but high velocity.
      • But if your motor has high rpm ie low torque use small diameter wheel.
      • It should be atleast 1 cm larger than motor dia
    • Wheel grip .
      • The grip of wheel is terrain dependent.
      • Don’t ignore the grip , itll decide your robots fate. If your wheel is too smooth then it will have problem on slope , sand ,oily surfaces etc
      • For loose surface use high grip(sandpaper,spikes from nails)
      • You also need to consider wear and tear on the wheel.
  • 30.
    • Wheel width .
    • Helpful in most cases but increases load on motor
    • The wider the wheels, the more the robot will tend to stay on course.
    • Wheel center hole diameter .
    • Wheel should be tightly fitted to motor shaft,else use screw,pin or nutbolt to fix
    • Mounting Your Robot Wheel Techniques Jamming .
    • Make sure the hole is perfectly centered!!!!
    • For a tight fit hole use a little superglue , and finally press fit (jam it) apply around the edges also.
    • For loose fit motor use a slip, polythene, rubber pipe lining
  • 31. Connecting to the Motor Shaft
  • 32. Castor wheel
  • 33.
    • MECHANICS OF THE ROBOT
    • it deals with the study of state of the robot under operating conditions.
      • statics
      • dynamics
      • energy calculations
      • acceleration
      • c.g. maintainance
  • 34.
    • Horizontal Center of Balance(The result is an unstable robot: the robot may not travel in a straight line and it might even tip over )
  • 35.
    • Vertical Center of Gravity
    • A robot with a small base but high vertical center of gravity risks toppling over. You can correct such a design in either of two ways: Reduce the height of the robot to better match the area of the base, or Increase the area of the base to compensate for the height of the robot.
  • 36.
    • Introduction to Mechanical Engineering Theory
      • Want to optimize your robot parameters mathematically?
      • Want to verify that an expensive motor you are about to purchase has enough torque?
    • Theory: Statics Statics is concerned about how a mechanical system would act if everything is perfectly motionless and rigid.
    • It is study of forces and moments during static condition of the robot.
  • 37.
    • Moment Arms Moment arms will probably be the most useful for you.
    • Moment = Force * distance
    • In case of lifting arms
    • If a gripper is attached ,mount the motor near to the axis of arm
    • If heavy weight is to be lifted then mount the motor such that it will counter balance the weight
    • Make arms from light material like aluminium sections
  • 38.
    • Theory: Dynamics
    • Dynamics is study of state of robot during moving condition.
          • Check the condition of wily and topple.
          • Placement of battery and accessories should be such that imbalance in weight is ignored.
    Velocity = circumference * rpm
  • 39. Torque = Distance * Force Distance = Wheel Radius Force = Torque / Wheel Radius
  • 40.
    • Theory: Velocity Requirements
      • C.G. should be maintained at the centre of the body as much as possible.
      • It is preferred that C.G. should be as near as the ground.
  • 41. Switches
  • 42.
    • Selecting a Switch
    • There are three important features to consider when selecting a switch:
        • Contacts (e.g. single pole single throw, dual pole dual throw)
        • Ratings (maximum voltage and current)
        • Method of Operation (toggle, slide, key,rocker etc.)
    ROBOTIC PLATFORM CONTROL PANEL Wired Wireless
  • 43.
    • TYPES OF SWITCHES
      • ON-OFF Single Pole, Single Throw = SPST
      • A simple on-off switch.
      • Apply on live wire
      • better to use a DPST switch to isolate both live and neutral.
      • (ON)-OFF Push-to-on = SPST Momentary
      • A push-to-on switch returns to its normally open (off) position when you release the button, this is shown by the brackets around ON. This is the standard doorbell switch.
      • ON-(OFF) Push-to-off = SPST Momentary
      • A push-to-break switch returns to its normally closed (on) position when you release the button.
  • 44.
      • ON-ON Single Pole, Double Throw = SPDT
      • changeover switch. For example, a SPDT switch can be used to switch on a red lamp in one position and a green lamp in the other position.
      • Dual ON-OFF Double Pole, Single Throw = DPST
      • A pair of on-off switches which operate together .it can isolate both the live and neutral connections.
      • Dual ON-ON Double Pole, Double Throw = DPDT
      • A pair of on-on switches which operate together .A DPDT switch can be wired up as a reversing switch for a motor(very useful for robotics)
  • 45.  
  • 46.  
  • 47.  
  • 48.  
  • 49.
    • POWER SUPPLY SYSTEM
    • BATTERIES
      • DIFFERENT TYPES OF BATTERIES
        • NON CHARGEABLE
        • RECHARGABLE
  • 50. Zinc-carbon battery - Also known as a standard carbon battery, Alkaline battery - Alkaline chemistry is used in common Duracell and Energizer batteries, the electrodes are zinc and manganese-oxide, with an alkaline electrolyte. Lithium-iodide battery - Lithium-iodide chemistry is used in pacemakers and hearing aides because of their long life. Lead-acid battery - Lead-acid chemistry is used in automobiles, the electrodes are made of lead and lead-oxide with a strong acidic electrolyte (rechargeable). Nickel-cadmium battery - The electrodes are nickel-hydroxide and cadmium, with potassium-hydroxide as the electrolyte (rechargeable). Nickel-metal hydride battery - This battery is rapidly replacing nickel-cadmium because it does not suffer from the memory effect that nickel-cadmiums do (rechargeable). Lithium-ion battery - With a very good power-to-weight ratio, this is often found in high-end laptop computers and cell phones (rechargeable). Zinc-air battery - This battery is lightweight and rechargeable. Zinc-mercury oxide battery - This is often used in hearing-aids. Silver-zinc battery - This is used in aeronautical applications because the power-to-weight ratio is good.
  • 51.
    • Most lead-acid and gel-cell batteries can be recharged using a 200- to 800-mA battery charger.
    • Standard NiCad batteries can’t withstand recharge rates exceeding 50 to 100 mA,
    • Nickel metal hydride, rechargeable alkalines, and rechargeable lithium-ion batteries all require special rechargers.
  • 52.  
  • 53.  
  • 54.
    • Estimate how long will the battery will last
    • Calculate load of your robot
    • Run the robot under full load condition
    • Measure the current consumption
    • Divide the battery rating (AHr) by this factor ,it will give running time in hrs
    • On inclines roughly it will draw twice the current
    • Golden rule:keep robot light or use more AHr battery,to last longer
      • Here are general rules that would get you really close.
      • If you have external (not inside the motor) gearing, reduce your efficiency by ~15%.
      • If you are using treads like on a tank robot, reduce by another ~30%.
      • If your robot operates on rough high friction terrain, reduce another ~10%. For example, a tank robot on rough terrain would have an efficiency of 100% - 30% - 10% = 60% or 0.6.
  • 55.
    • ASSEMBLING
    • CONNECTION OF WIRES TO MOTORS.
    • CONNECTION OF WIRES TO SWITCHES.
    • SOLDERING LOOSE JOINTS.
    • TAPING OPEN JOINTS.
  • 56. Soldering Technique
  • 57. 1. The iron is hot and can easily damage parts, cause burns, or even start a fire. Keep the soldering iron in its holder when it is not being held. 2. Make sure that there is a damp sponge available used for cleaning off and tinning the tip. 3. Always make sure that the tip is tinned when the iron is on. To tin the iron, clean the tip and wipe it on a damp sponge and then immediately melt some fresh solder onto the tip. 4. A cold solder joint is a joint where an air bubble or other impurity has entered the joint during cooling. Cold solder joints can be identified by their dull and mottled finish. Cold joints are brittle and make poor electrical connection. 5. Do not hold the iron against the joint for an extended period of time (more than 10 seconds), since many electronic components or the printed circuit board itself
  • 58.  
  • 59.  
  • 60. TORQUE Torque is the force the motor exerts upon its load. The higher the torque, the larger the load can be and the faster the motor will spin under that load. Reduce the torque, and the motor slows down, straining under the workload. Reduce the torque even more, and the load may prove too demanding for the motor. The motor will stall to a grinding halt, and in doing so eat up current (and put out a lot of heat). Torque is perhaps the most confusing design aspect of motors. At its most basic level, torque is measured by attaching a lever to the end of the motor shaft and a weight or gauge on the end of that lever,
  • 61.
    • Tips for Reducing Weight
    • Nickel-cadmium and nickel metal hydride batteries weigh less, volt for volt,than their lead-acid counterparts(may not deliver the amp-hour capacity)
    • Less powerful motors weigh less than the originally specified motors(it isn’t unusual to see a situation where a 10 percent decrease in battery weight results in a 50 percent reduction in overall robot weight.)
    • Beware of the Heavy Frame
  • 62.
    • Types of Failures
    • MECHANICAL FAILURE
    • ELECTRICAL FAILURE
  • 63.
    • Mechanical problems are perhaps the most common failure in robots. The typical source of the problem is that the materials or the joining methods you used were not strong enough.Avoid overbuilding your robots (that tends to make them too expensive and heavy), but at the same time strive to make them physically strong.
    • When possible, avoid slap-together construction, such as using electrical or duct tape.
    • nuts and bolts,Epoxy and hot-melt glues are among the most permanent
  • 64.
    • Some electrical problems may be caused by errors in programming, weak batteries, or unreliable sensors.
    • Loose wires can come off. mistakes in wiring,Parasitic signals and stray capacitance can cause marginal circuits to work,
  • 65.  
  • 66. Chandrayaan 2 Moon Rover
  • 67. Total Project Solutions E7/83F, Ashoka Society Arera Colony,Bhopal ,462016(M.P.) +91-9826015410/9826050109 +91-755-2420735 www.onlineTPS.com Starting Robotics