Grabber Challenge

# Grabber Retrieval

The Grabber unit has the ability to grab and pick-up objects. The arm is operated by a single motor that first closes, then lifts.

Select the challenge below for the software you are using.

The Challenge: The Grabber unit needs to collect a weight and take it to the end point.

Below are the figures to assist in this challenge for the Grabber unit.

Action Left motor power Right motor power Number of rotations Threshold value
To travel forward one grid square*1 100% 100% 3.8 n/a
90° turn right 25% -25% 1.4 n/a
Wall detection n/a n/a n/a <15
Beacon detection n/a n/a n/a <5

*1 The maze is made on a 5x5 square grid

The Grabber Arm Controls: This is powered by a 'medium motor'. To close and lift the arm you will need to activate this motor at 50% speed for 13 rotations. To lower and open it's 13 rotations at -50% speed.
Do NOT exceed 13 rotations in either direction on the medium motor or you will freeze your program and cause damage to the robot's gear system.

Hint: The grabber unit is easier to steer when the arm is raised, however, to detect the beacon it will need to be in the lowered position, as the IR sensor is part of the lifting arm.

How would you adapt your program to meet the new challenge given below?

The Challenge: Grabber need the additional weight to topple the seesaw and allow it to escape.

Below are the figures to assist in this challenge for the Grabber unit.

Action Left motor power Right motor power Number of rotations Threshold value
To travel forward one grid square*1 100% 100% 3.8 n/a
90° turn right 25% -25% 1.4 n/a
Wall detection n/a n/a n/a <15

*1 The maze is made on a 5x5 square grid

The Grabber Arm Controls: This is powered by a 'medium motor'. To close and lift the arm you will need to activate this motor at 50% speed for 13 rotations. To lower and open it's 13 rotations at -50% speed.
Do NOT exceed 13 rotations in either direction on the medium motor or you will freeze your program and cause damage to the robot's gear system.

Hint: The grabber unit is easier to steer when the arm is raised, however, to detect the beacon it will need to be in the lowered position, as the IR sensor is part of the lifting arm.

How would you adapt your program to meet the new challenge given below?

Members of the Aberystwyth Robotics Club can share a link to their MakeCode program or send a Lego Mindstorms program directly through the club's Discord server.

Non-members who wish to see if their program works can email nar25@aber.ac.uk either the Lego Mindstorms file or a link to their MakeCode program