Building Guide:

Tools

The robot is designed to be built with a limited set of tools.
You will need the following:

  • A soldering iron with a small bit, plus solder
  • A small pair of side cutters for clipping component leads and wires to length
  • A small pair of pliers for holding parts and nuts while being tightened and optionally a long nosed pair.
  • Flat and cross head screwdrivers for tightening nuts and bolts
  • A digital multi meter to measure voltages and resistance values. Typically available for about £5 on EBay

Parts

  1. Main Board

    UKMARS Main Board PCB

    Resistors – R1, R2, R7, R8 10KὨ; R3 4.7KὨ; R4 2.2KὨ; R5, R9 1KὨ; R6 470Ὠ – all 0.125 or 0.25 watt

    Capacitor – C1 100nF (usually marked 104)

    Switches – S1 3 pin on/off switch, S2 6mm x 6mm tactile switch, S4 4way DIP switch Rapid-online Order code: 80-0334

    Diode – 1N5817 Schottky Barrier Rectifier Diode – Rapid-online part no 64-8473

    LED – any 3mm indicator LED

    Integrated Circuit – 74LS86N

    Motor driver board – Sparkfun TB6612FNG with 2 x 8 header pins soldered in

    Arduino Nano – with 2×15 header pins soldered in

    Sockets – 2x 15 way single row headers for Arduino Nano, – Rapid-online Order code: 19-0086

    Pin Headers – J1 – 14 way single row for sensors, J2,J3 – 6 way single row for motors, Serial – 4 way . – use 1x 36 way Single row header (PCB) plug e.g. Rapid -online Order Code: 22-0545 For J4 battery connector either use a 3 way pin header or directly wire the battery connector lead into the main PCB

    Battery connector lead – PP3 9V battery connector lead – Rapid-online Order code: 18-0546
  2. Line Following Sensor

    Two Options: a) the IR version, b) the visible light version

    UKMARS Line Sensor PCB

    Resistors – R1, R8, R9 390Ὠ; R2 10KὨ; R3, R4, R5 68Ὠ; R6, R7, R10, R11 4.7K Ὠ

    Transistor – BC337-40 Bipolar NPN transistor- Rapid-online Order code: 50-3113 or PN2222ABU NPN Transistor – Rapid-online Order code: 81-0257

    Capacitor – C1 100µF electrolytic – Rapid-online Order code: 11-3508

    High brightness LED Option a) 3 x Osram SFH409. Option b) 3 x Truopto OSHR3131A-NO 3mm 3000mcd – Rapid-online Order code: 55-0066

    Phototransistor – Option a) 4 x Osram SFH309FA. Option b) 4 x Vishay BPW85C 3mm – Farnell part no 104-5380
  3. Wall Following Sensor

    Two Options: a) the IR version, b) the visible light version

    UKMARS Line Sensor PCB

    Resistors Option a) R1, R2 390Ὠ; R3, R4, R5 1.8kὨ; R6 390Ὠ; R7 10KὨ; R8 33Ὠ; R9, R10, R11 33Ὠ;

    Resistors Option b) R1, R2 390Ὠ; R3, R4, R5 1.0kὨ; R6 390Ὠ; R7 10KὨ; R8 33Ὠ; R9, R10, R11 10Ὠ;

    Transistor – BC337-40 Bipolar NPN transistor- Rapid-online Order code: 50-3113 or PN2222ABU NPN Transistor – Rapid-online Order code: 81-0257

    Capacitor – C1 100µF electrolytic – Rapid-online Order code: 11-3508

    High brightness LED Option a) 3 x Osram SFH4550 5mm Option b) 3 x Vishay TLCR5800 5mm

    Phototransistor – e.g. 3 x Vishay BPW85C 3mm – Farnell part no 104-5380 or BPW96B
  4. Motors and mounts
    2 x N20 12mm micro gearmotors. Suggested gear ratio is 20:1 but anything from 10:1 to 60 :1 is OK. If you want to use encoders you need one with the extended rear shaft. Pimoroni or Polulo have a good range e.g. the Pimoroni 20:1 extended shaft micro gearmotor

    Motor mounts – These may be 3D printed or bought from Polulo, Kitronic, Pimoroni or Ebay. Note that there are several types available. See assembly notes
  5. Wheels
    The chassis is ideally suited to 2 x 32mm diameter wheels with 3mm D shaft centres. These may be 3D printed or bought with tyres from Polulo, Kitronic or Pimoroni. If you are 3D printing them you will need 25mm “O” rings to use as tyres, available on Ebay.
  6. Battery – Any PP3 9Volt nominal rechargeable battery will do. NiMh ones (e.g. from B&Q) are heavier than the Lithium ion ones that can be recharged from a 5V USB supply (available on Ebay or Amazon)
  7. Battery holder clips
    3 metal paper clips and a small elastic band
  8. Connecting wire
    Multiway wire is useful for connecting the sensor boards to the main board
  9. Sensor Board Connector
    Two options: 1) 5 x Dupont F to F connector leads (from Ebay) cut in half, or option 2) 10 way e.g. Molex wire to board connector 2.54mm. e.g. Farnell part no 2751624 plus crimp inserts 10 x Farnell order no 2888893 or pack of 100 Farnell order no 2424111
  10. Motor connector
    Two options: 1) 6 x Dupont F to F connector leads (from Ebay) cut in half, or option 2) 2 x 6 way e.g. Molex wire to board connector 2.54mm. e.g. Farnell part no 1756789 plus crimp insets as in above item
  11. Nuts & Bolts
    Depending on the motor mounts used you may need four M2.5 bolts and nuts for them. Otherwise, all the other nuts, bolts and spacers used are M3 size. If you use M3 bolts for the motor mounts you will need to slightly enlarge the motor mount holes in the main PCB to accommodate these, as they are current drilled for M2.5 bolts.

    Two 20mm length bolts are used with 10mm spacers to hold the line follower sensor board in place.
    One 12mm length bolt with a 5mm spacer can be used as the front skid. The M3 bolts can be metal or nylon as you wish.