My Projects

Published 16 Jan 2020

Explorer


Overview

I recently came across parts of a robot system that turned out to be parts of a “Rover 5 Explorer kit”1) type robot platform. Rover 5 is a tracked chassis on which can be mounted a variety of robot controllers. Explorer is an interface board to facilitate connection of an Arduino or similar controller to the robot platform. An IR compound eye mounted on a pan/tilt assembly can be used to track moving objects or as a simple range finder.

The mainboard circuitry is similar to that found on the Dagu “Mr. General” and “Mr. Tidy” robots, and the software for the IR compound eye will work the same.

The robot was made by Dagu2)

Hardware description

The hardware I have consists of a mainboard 3), 2 servo motors 4), and a tilt/swivel bracket 5) with an infrared “compound eye” 6). The mainboard has a prototyping area, corner mounted infrared transmitter/receiver sensors, power regulators, h-bridge motor driver, motor current level sensor, motor rotary encoder interface, status LEDs, many servo/sensor plug/sockets, NiMH battery charging circuit, and mounting holes to suit Arduino boards, breadboards and servos.

rover 5/explorer mainboard, top rover 5/explorer mainboard,bottom

rover 5/explorer mainboard mounting hole layout

I found it useful to have a template that I could print out at 100% (I printed it as 171mm long by 132mm wide, but printer might not be precise, so compare it with the board and reprint scaled up if necessary) and use for marking mount hole positions on my platform. The holes are colour coded as follows:

Colour Purpose
OrangeMainboard mounting
BluePan/tilt servo mounting
PinkBreadboard mounting
YellowArduino Mega mounting
RedArduino Uno etc mounting
BlackHeat sink mounting

The tilt/swivel bracket, servos and compound eye form the “head” of the robot, and with suitable software allow the robot to track objects close to it (< 200mm).

universal mount tilt/swivel bracket 9g servo

IR compound eye, front IR compound eye, back

My version of the mainboard7) can be seen in some photos of the Rover 5, eg https://sites.google.com/site/daguproducts/home/download-page/IMG_2297 (small).jpg, but most photos show a presumably later version with a row of 6 screw terminals at the rear left side of the board.

The corner infrared sensors are vulnerable to being displaced by collisions, and end up effectively in-operative. So some consideration needs to be made to protect them, eg mounting them so they do not protrude beyond the edge of the chassis, or adding a bumper/guard.

Software

Despite the board having full H-bridge driver hardware, the example Explorer code (file dated 24/01/2011) assumes that the main drive motors are of the analog pulse-width driven, continuous rotation, servo type. That is they only require a single control line for forward, back and stop control. The example software for the “Mr Tidy” robot handles normal PWM DC motors, and has the same corner infrared collision detection hardware, but it also has a lot of other features and so requires a controller with a lot more I/O pins than an Arduino UNO.

The infra-red corner sensors can either be read as digital or analog inputs. The Mr Tidy example code treats them as digital inputs - effectively making them fixed distance, very short range sensors. The Explorer example code treats them as analog inputs - so although still short range you can set a distance threshold.

References and Additional Resources

Rover 5

IR Compound Eye