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Introduction For the assignment, you will design and simulate a robot to do the following tasks: ? Search an unknown environment for a known object

Mechanical Engineering

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Introduction For the assignment, you will design and simulate a robot to do the following tasks: ? Search an unknown environment for a known object. ? Stop next to the object (at this point the user will pause the simulation and place the object on the robot before restarting the simulation). ? Once the robot detects the weight of the object, it should measure the weight and return it to the start point. ? Your work should demonstrate a well-designed robot (on Inventor), functional program code (on Webots) and simulations of any circuits used (on MultiSim and Tinkercad). Your work will be submitted as a video presentation of your accomplishments. The marks indicated below are the maximum marks for each section, there are 100 marks available in total. Assignment - criteria 1) Webots Simulation Task (30 marks) The Webots part of the assignment is as follows. Note that you should write only one program to complete all the required tasks. You should fully label your code with comments using //. a) In Webots, create the environment: ? Create a room of size 10m x 10m with a floor tile size of 0.5m x 0.5m. Have the room bounded by a perimeter wall of height 0.1m. In the centre of the room, create a cylinder of radius 0.05m and height 0.001m and choose an appropriate colour for this object. Position it to mark the centre of the room whilst not being an obstacle for the robot. ? Construct a differential drive robot of dimensions (l,w,h) of no greater than 0.25m x 0.25m x 0.3m. You may place any sensors on the robot that you think are suitable to help complete the following tasks. Place this robot at the centre of the room. ? Construct 6 boxes of various sizes and colours but with dimensions (l,w,h) of at least 0.5m x 0.25m x 0.3m and place these randomly at least 2m from the centre of the room. ? Construct a cube with edges of length 0.1m and place this behind one of the boxes (so it cannot be seen by the robot). It should be a distinct colour. b) Perform pre-programmed movement: ? Write a controller to drive the robot along a square trajectory. The square should be of size 1m x 1m and the robot should finish at its starting location at the centre of the room with the same orientation. ? Once the robot has completed moving in a square, the robot should then complete a figure 8 trajectory (this can be two circular trajectories, one clockwise, one anticlockwise). The radius of each circle should be 0.5m. Again the robot should finish in the same position and orientation as the start. c) Once completing these pre-programmed moves, the robot should immediately move around the environment and locate the randomly placed cube. You will need to explain the search algorithm used. The robot should not bump into any objects whilst completing this task thus the robot should contain appropriate collision avoidance sensors. Once the cube is located, the robot should stop as closely as possible to it without touching it. Once the robot is stopped you should pause the simulation. d) With the simulation paused, you should drag the cube on top of the robot and then restart the simulation. The robot should automatically detect this object on the robot and weigh it (you do not need to have Webots print out this weight although you should demonstrate that your program is performing this weighing). The robot should then return to the start point (centre of the room) whilst carrying this cube. You can use any sensor you wish to perform this ‘return to centre task’ but an intelligent control algorithm will gain higher marks (for example random walk back to the start is one solution but is not ideal, what is the quickest / most efficient trajectory back to the start – you should explain how you have achieved this in your presentation). 2) Tinkercad Prototype Task (30 marks) The Tinkercad part of the assignment is as follows. a) The robot is to contain a single force sensor to measure the weight of the object. Design a circuit to convert the resistance change in the sensor to a voltage utilising the full input range of an Arduino’s analogue-to-digital converter. You can assume the resistance of the force sensor is 1.3 k? and will change to 1.2 k? under maximum load. Simulate your circuit on MultiSim to demonstrate it is functional. b) Using Tinkercad, construct the complete circuit that would replicate you constructing the electronics for your robot. The electrical circuit should simulate as many components as possible used in the Webots program including any motors and sensors - this also includes the force sensor designed on MultiSim, note that you should use a force of 8.85N and 10N to obtain the required resistances. Run the simulation to demonstrate each part of your circuit works. c) In your Tinkercad simulation, you are to program the controller for the robot to perform the basic square trajectory and figure 8 trajectory as done in task 1b. Your program code should replicate the coding structure used in Webots, i.e. write an Arduino function to replicate the Webots wb_motor_set_velocity(motor, speed) command, etc. To demonstrate your code, you should run the simulation and monitor the speed of the motors. The Webots coding should be shown alongside your Arduino coding in your video submission to demonstrate their similarity. d) For parts that are not directly available in Tinkercad (for example a camera), you should perform a web search for a suitable part and in your presentation, show a sketch on how you would connect this up to the Arduino and give a brief explanation of the program code required to operate it. 3) Inventor Design Task 4 (20 marks) You need to produce a full assembly drawing of your robot in Inventor. Your structure should be structurally robust without being excessively heavy. Be sure to include good design practises, for example bearings in suitable places to support loads. You do not need to add individual wiring but wire tracking should be indicated by appropriate cabling structures in your design (for example holes in the chassis to feed wires through). Any parts that would need custom manufacturing needs to be accurately drawn. Specialist parts (for example Arduino, sensors, etc) can be approximated by a box of similar dimensions. In your presentation, you should discuss the main mechanical design features of your robot. 4) Sensor Design Task (20 marks) The distance sensors have a limited minimum range. You should design your own distance sensor using an LED and photodiode which will operate at close range. To overcome the problem of potential background light, the LED should be programmed to flash and the photodiode receive circuit designed to only measure light at this flashing frequency using appropriate filters. This flashing frequency should be WXYZ Hz where WXYZ is the last 4 digits of your student number (note if W=0 then you should use a frequency of 10XYZ). Please indicate your student number during the presentation. The sensor should only have connecting wires for power, ground and output signal. The output signal should utilise the digitising range of an Arduino and be a voltage corresponding to distance measured. Once designed, you need to demonstrate the functionality of each part of your circuit design on MultiSim simulations and then demonstrate the overall performance of this circuit. Submission Once completed, you need to produce a video presentation of your work of length up to 10 minutes (8 minutes to 12 minutes will be acceptable). You are only allowed to submit one video presentation. The video should show simulations running, details of design, coding and a voice over explaining what is happening.