--- title: "Delivery robot" subtitle: "AI robots · Final challenge: Delivery robot · Lesson 5" --- # Delivery robot **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** Delivery robots on footpaths and in hospitals follow instructions, but their own sensors always get the last word: if something is in the way, they stop, whatever they were told. :::teacher-note **In one sentence:** Students build a sign-driven delivery robot in three milestones; its distance sensor overrules the model, it reports back through the bridge, and it counts deliveries. **Students should be able to say:** I can make a robot's own sensor overrule a model's label. I can send a robot's readings back to the computer through a bridge. I can explain why a safety check goes first in an if, else if chain. **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. ::: ## Predict ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/aef0dfb1fd15.png?v=f050f579f5f5bb27) :::keep-together **The model reads Go (twice), and the robot sets off. A box is in its way. What happens?** ☐ It stops at the box ☐ It turns back ☐ It drives round the box ☐ It drives into the box My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** It drives into the box. The model only reads the sign; nothing in this program looks at what is in front of the robot. ::: ## Run Run the program in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Investigate :::keep-together ### Model or sensor **Which part should decide each of these?** Groups: The model (camera on the sign), The robot's own sensor - Which way the sign says to go: {{field-15}} - Whether a box is right in front of the robot: {{field-15}} - Whether it's safe to keep driving forward this moment: {{field-15}} - Whether the delivery stop has been reached (the Stop sign): {{field-15}} ::: :::teacher-note **Answer:** Which way the sign says to go → The model (camera on the sign); Whether a box is right in front of the robot → The robot's own sensor; Whether it's safe to keep driving forward this moment → The robot's own sensor; Whether the delivery stop has been reached (the Stop sign) → The model (camera on the sign) ::: :::keep-together ### Jo's robot **Jo checks the distance in the last else if, after Go, Left and Right. Her robot still drives into boxes on Go. Why?** ☐ The watchdog stops the check ☐ Boxes are invisible to the sensor ☐ When the mode is Go, the Go branch runs first and the distance check is never reached ☐ The sensor is broken ::: :::teacher-note **Answer:** When the mode is Go, the Go branch runs first and the distance check is never reached An if, else if chain runs only the first branch that matches. A check that must always win goes first. ::: :::typical ## Milestone 1: the sensor wins Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/beefd5df10fa.png?v=625dae6785649b0f) ::: ::: :::typical ## Milestone 2: report back - The robot sends its **distance** by radio twice a second. - When it stops for something, it sends **blocked 1**, once; when the way is clear, **blocked 0**, once. The bridge passes these on to the board, where they appear as values (in_dist, in_blocked). Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/0f4f2661510a.png?v=1a3fb050e3aee129) ::: ::: :::typical ## Run Run the program in the tutorial. Was your prediction right? What was different? {{lines-2}} ::: ## Make: Milestone 3: deliveries Count **deliveries**: a Stop sign that arrives while the robot is going. Send the count back and show it when the robot is shaken. Then make it yours: a library book trolley, a lunch-order runner, a parcel robot. Change the signs, lights and sounds to suit. Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/a5d763c240a4.png?v=0fc1ea59a91dc1b8) ::: :::wider ## On real robots - **Each team needs its own radio group** for its bridge and robot. - A real distance sensor misses thin things (chair legs) and soft things (a jumper). What else should a delivery robot check before it moves? - Your robot trusts the model only for the sign, and its own sensor for safety. Real delivery robots do the same with many more sensors. ::: ## Exit ticket :::keep-together **Why does the distance check go before the Go branch?** {{lines-3}} ::: :::teacher-note **Answer:** An if, else if chain runs only the first match; the safety check must win whatever the model says, so it goes first. :::