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

Main Board

UKMARS Main Board PCB – versions 1.1 and 1.3a
Resistors – R1, R2, R7, R8 10KὨ; R3 4.7KὨ; R4 2.2KὨ; R5, R9 1KὨ; R6 470Ὠ – all 0.125 or 0.25 watt
For Bluetooth module – R10 3.3kὨ; R11 2.2kὨ
Capacitors – C1 100nF (usually marked 104). For v1.3a board C2 and C3 470µF 10V low height 12mm or less
Switches – S1 3 pin on/off switch, S2 6mm x 6mm tactile switch, S4 4way DIP switch Rapid-online Order code: 80-0334
Diodes – D1 1N5817 Schottky Barrier Rectifier Diode – Rapid-online part no 47-0824
For Bluetooth module – D2/D3 1N4001 or any small signal diode (marked as D2 on V1.1 board and as D3 on V1.3a board)
LED –For V1.1 board only, 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 – Two 15 way single row headers for Arduino Nano, – Rapid-online Order code: 19-0086. One 4 way single row header if using the Bluetooth module
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

Line Following Sensors
Full size 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

Half size visible light line following sensor
UKMARS 1/2 size Line Sensor PCB
Resistors – R1, 390Ὠ; R2 10KὨ; R3, R4, R5 68Ὠ; R6, R7, R10, R11 2.2K Ὠ R8, R9 1KὨ;
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 3 x Truopto OSHR3131A-NO 3mm 3000mcd – Rapid-online Order code: 55-0066
Phototransistor 4 x Vishay BPW85C 3mm – Farnell part no 104-5380 08
Connector socket 10 way single row socket header- Rapid-online Order code: 19-0085

Wall Following Sensor
Two Options: a) the IR version, b) the visible light version
UKMARS Wall Sensor PCB
Resistors Option a) R1, R2 390Ὠ; R3, R4, R5 1.8kὨ; R6 390Ὠ; R7 10KὨ; R8 33Ὠ; R9, R10, R11 33Ὠ;
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

Motors and mounts
Motors – 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

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.

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) The Liter 9V 1200mAh one available on eBay is very good as it can be recharged with just a USB micro cable while on the robot and has capacity LEDs on it

Battery holder
for v1.1 board – Three metal paper clips and a small elastic band. For v1.3a board use Velcro on the board and the battery

Sensor Board Connector
The latest sensor boards plug directly into the J1 connector at the front of the board

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

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.