MCP Documentation

1. Introduction

This section describes all aspects of the power system for the MCP. Several people worked on different parts of this system at different times including but not limited to: Schuyler Salz, Fred Martin, and Kyewook Lee.

2. Overview

GIVE ME POWER! 

All robots require a power system. Given the component based construction of the MCP a variety of different power supplies were needed. The base Power Wheels (tm) toy that was our construction platform required 12V for its drive motors. Our CPU also required 12V in, but we felt it best to keep the motor power supply separate from the CPU power supply. Lastly, some of our subsystems were designed to run on 5V, creating the need for a third power bus and a voltage reduction circuit.

3. The Three Circuits

+12V Motor Circuit 

The original battery from the MCP's days as a kids toy is stored under the hood.

Figure 3.1: Motor Power Source

A cradle for the battery was already in place, as well as a connector cable to power the drive motors. As we kept the original drive motors it made sense to keep this battery setup in place, especially given the need for separate logic and motive power supplies. This battery supplies power to the steering motor as well as the drive motor.

+12V Logic Circuit 

Several devices, including the CPU and the GPS operate on a 12V DC supply. We use a large 12V battery for all power requirements except drive components.

Figure 3.2: Purchased surplus

Specifically this provides power to: The CPU, GPS, Display Sign, Speakers and the 12V to 5V conversion circuit. All connections to the 12V logic power supply are made through a fuse board.

Figure 3.3: 12V Power Board

+5V Logic Circuit 

There are two devices on the MCP that require a 5V power supply. The Serial Sense board that controls the steering motor and associated sensors, and the sonar control board. A simple voltage reduction circuit was built around two LM305 voltage regulators.

Figure 3.4: Schematic for the 5V reduction circuit

One of the 5V outs ended up as a status light, as half the circuit was more than sufficeint for our needs.

Figure 3.5: 5V Reduction Circuit

Common Ground 

We installed a heavy duty connection strip for use as our ground bus.

Figure 3.6: Common Ground

All devices use this common ground.

Connection Rules 

4. Appendices

Appendix A: Power Connections by Subsystem 

CPU: 12V logic

Sign: 12V logic

Speakers: 12V logic

GPS: 12V logic

Sonar MUX: +5V logic

Steering Control: +5V logic

Drive Motors: +12V motor

Steering Motor: +12V motor

Note: THIS SECTION STILL IN PROGRESS. Connection details and pictures pending

Appendix B: Source File Listing 

The 5V reduction circuit file can be found at /usr/cs/fac4/fredm/548/student/ssalz/5VPowerBus.BRD