3MEMS3: Robot Model in Solidworks
Due to ongoing delays, I’m yet to receive the robot I was due to be working on. With no sign of it yet I decided the CAD model I mentioned in my previous blog would be put to better use being displayed than it would be sitting on my harddrive.
As with all my CAD, I am using Solidworks 2019. Solidworks is the chosen CAD program in Trinity and they also sponsor my formula student team. I am using SW 2019 over the 2020 version as it is team standard, 2020 files are not compatible with 2019. This means I can’t use Solidworks Visualize for my renders but fortunately, there are usually minimal changes year on year so any tips I share in this post will be applicable to many different versions.
I have been using Solidworks for about five years now and despite the initial learning curve that comes with any new software it is a very intuitive programme. The most commonly used features have the biggest icons and the overwhelming majority of geometries can be made using these basic tools.
As can be seen, this robot is relatively simple in design, this benefits the manufacturer and the end-user who has to assemble the robot. It also means that this is a fairly basic exercise in CAD, There’s not much to say with regards to the modelling process as 90% of the time was spent Sketching, extruding patterning and using the hole wizard. This allowed me to focus on making the model as proficiently as possible.
In this blog I’ll give some tips and outline some simple features in Solidworks that greatly help this process. Solidworks is best used as an academic tool and for more simple CAD models and simulation analysis, CAD packages such Catia or SiemensNX provide more advanced functionalities. While products like Ansys expand on FEM and CFD., but back to Solidworks.
Beginners often don’t consider the plane in which the initial sketch of the part is started, pausing for a moment to consider this as well as the position of the origin can save time when you start to form these parts into an assembly.
Ensuring sketches are accurate and defined and using appropriate relations is essential when you are making a model whose dimensions may very well change, as is the case with this robot model which I am modelling despite not having the parts to hand.
Hole wizard integrates standard hole types and sizes into a package that easily allows the placement and dimensioning of these holes
The mirror feature allows a feature to be copied symmetrically across a face or plane, this works great when used along with a linear pattern for features such as micro controller pins.
Linear/Circular Patterns allow features to be replicates along a line or about an axis, I used all of these features a lot and patterns especially when modelling the electronics and wheels and tires.
Bear in mind you can mirror and pattern multiple features in one use of the command to pattern details modelled by two extrusions such as the pins of the microcontroller.
Many electronics are standard parts and CAD files can be found on various community file share sites, I’m personally not a fan of using CAD files that are not made by myself or align with a regulated standard in Solidworks toolbox (such as the fasteners I have used in my assemblies). Files from non-official sources are often unreliable and can be easily replicated in a short time yourself.
Fillet corners in the sketch before extrusion to save on adding separate fillet features that quickly clutter your design tree
Materials were assigned to all components as I went. This not only allows us to make more aesthetic renders but will also reveal some approximate parameters of the robot. Using the mass properties tool in the Evaluation tab we can find the centre of gravity (COG) which will come in handy when trying to optimise the modifications that I’ll make later.
There are two areas that will need to be modified. Firstly I must add some form of stabiliser to the robot to help it complete an obstacle course. I plan on doing this through some form of an additional wheel that will be secured to a 3D printed arm.
The robot will also need to have some form of basket mounted on top to catch some ping pong balls. As part of the obstacle course, the balls will be fired by a launcher that is also currently in the design phase. This launcher is entirely my own design that will fully conform to the outlined rule set.
Both of these modifications will be the subject of future blog posts, as work has already begun on these they will out very soon and will feature the use of some innovative engineering tools to maximise the potential of our on-campus 3D printers!
I currently have another four posts underway in my drafts, it’s been a busy few weeks of design but very enjoyable. Stay tuned for the fun stuff.
