---
title: "Two-motor drive base"
subtitle: "Capstone projects · Years 9–10: move it · Lesson 4"
---

# Two-motor drive base

**Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}}

> **Key question:** Every robot competition starts with the same question: can it drive where you want, for long enough, without falling apart?


:::teacher-note

**In one sentence:** A Years 9–10 design project: a two-motor drive base for a line or obstacle course, with a battery chosen against the brief, steering planned, built in a simulator then for real, and tested on a timed course.

**Students should be able to say:** I can choose a battery and motors against a brief. I can plan a robot's steering from its sensors. I can test a robot on a course and evaluate it with data.

**Width:** the unmarked parts are the floor every student does (predict, run, investigate and make). Typical adds the modify practice; wider adds the real-world contexts. They add contexts, not difficulty. Students work in the online tutorial alongside this sheet.

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## Inquire: the brief


:::keep-together

**Sort each line of the brief: a criterion (what it must do, which you can test) or a constraint (a limit you must work within)?**

Groups: Criterion, Constraint

- Completes the course in under 60 s: {{field-15}}
- Leaves the line at most once: {{field-15}}
- Runs for 30 minutes on one battery: {{field-15}}
- Two DC gear motors and a motor driver: {{field-15}}
- Battery 6–9 V, at most 150 g: {{field-15}}
- Chassis fits in 20 × 20 cm: {{field-15}}

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:::teacher-note

**Answer:** Completes the course in under 60 s → Criterion; Leaves the line at most once → Criterion; Runs for 30 minutes on one battery → Criterion; Two DC gear motors and a motor driver → Constraint; Battery 6–9 V, at most 150 g → Constraint; Chassis fits in 20 × 20 cm → Constraint

Criteria are what you will test at the end; constraints decide what you are allowed to build with.

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## Develop: plan before you build


:::keep-together

### Steering

**The line drifts left under the robot. To steer back, the robot should…**

☐ Stop both

☐ Slow the left motor (or reverse it) and keep the right one going

☐ Speed up both motors

☐ Slow the right motor

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:::teacher-note

**Answer:** Slow the left motor (or reverse it) and keep the right one going

Turning towards the line: the inside wheel slows.

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## Create: build it


**In the simulator.** 

**For real.** 

Work in the tutorial. Plan first: what will you change, and how will you test it?

{{box-4}}


:::wider

## Test: run your table


**Run the tests.** 

**Fix and re-test.** 

Work in the tutorial. Plan first: what will you change, and how will you test it?

{{box-4}}

:::


## Evaluate: against the brief


:::keep-together

### Which is evidence?

**Which is the strongest evidence that the design meets a criterion?**

☐ My partner said it looks good

☐ It worked when I tried it

☐ The code has no errors

☐ A test from the table that set the input and recorded the expected result

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:::teacher-note

**Answer:** A test from the table that set the input and recorded the expected result

A planned test with a recorded result is evidence; everything else is a feeling.

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## Exit ticket

:::keep-together

**Name the three numbers you checked to choose your battery.**

{{lines-3}}

:::


:::teacher-note

**Answer:** Voltage (in the driver's range), run time (capacity × 80% ÷ current) and weight.

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