Ideas
- 3D priter with additional degrees of freedom for non-planar printing
- Modular robotic system that can snap together, one style of joint
- Telemanipulated robotic arm
I'm not really sure what exactly I want to do for my final project yet, I do think I want it to be some form of robot or tool that is designed with a specific purpose in mind. I don't want to make something just to make something.
10/15/25
I think I have decided that I want to move forward with the idea of making a modular robotics system as my final project. There would be a few main components that I would need to design including a control hub, a drive component, interchangeable gear boxes, and different linkages. The PCB that I made during EDA Development week will be super useful for prototyping for this final project. I do have to revamp it though as I am not sure that the stepper drivers actually work. I plan on redesigning the PCB based off of the model on the class website.
Week 8
It has been a while since I updated my final project page but I have been thinking about it a lot and am ready to make some more concrete goals and
decisions of what to pursue.
I want to start by trying to outline the fundamental goals of my final project so I know just what it is that I am aiming for.
Goals:
I want to design a modular robotic system with two different kinds of actuators. One linear and one rotational actuator. For each actuator,
I want to be able to measure its absolute position using external sensors improving the overall control system and accuracy of the system as a
whole. Additionally, I want each component to be standalone, as in no external wires. I want all of the communication to take place wirlessly and
have power transfer through the joints of the system. As for the controls of the system, I want to be able to control the exact location of the actuators
and if in a system, know the aboslute position of the system. Through software I want to account for potential errors in displacement using the poisition
sensors in the actuators. For example, if a stepper misses a step, I want to be able to detect that and then add an additional step to its rotation to
account for that.
Parts of the project
- Linear and rotational actuators
- Ligaments between the actuators
- Control of individual actuators
- Control of actuator systems
- Communication between actuators
Linear actuator
- Use a ball screw to transmit rotation motion into linear motion
- Use linear rails to support the linear motion from the ball screw
- A platform that enables the connection between additional actuators or ligaments
- Some form of range detection to determine the location of the platform along the linear rails
- Wireless communication
Rotational Actuator
- Use a stepper motor with a cycloidal drive for increased torque
- Magnetic encoder for position detection
- Wireless communication
Ligaments
- Design some kind of universal connection system to be able to connect to actuators
- Right angle ligament
- Straight ligaments
Wireless control of individual actuators
- Reliably send and recieve data between actuator and computer
- Real time position correction. Ie. if a stepper motor is moved or out of position from the last defined position, it moves itself
- Speed control
- Artificial angle limits
Wireless control of mulitple actuators
- Forwards and reverse kinematics of the system for control
- Synchronus motion between multiple actuators at once
- Control from my laptop
There is clearly a lot to acomplish with not much time. I want to start by getting simple versions of the actuators working, without position detection. I think my focus of output devices week will be developing initial versions of both the linear and rotational actuators. This means that I will need to drive a stepper motor, I could continue pursuing the DRV8428 which I will likely do, however, I will simultaneously work with a broken out stepper driver that I have gotten to work before on a bread board enabling me to move forward with design and testing. This will also require me to develop initial 3D models of both the linear actuator and my cycloidal drive. This week I started work on the design of the drive and have used ChatGPT to write a python script to export a DXF of the unique shapes of a cycloidal drive(ADD PYTHON SCRIPT).
Action Items for Week 8:
- 3D model of basic linear actuator
- 3D model of cycloidal drive
- 3D model of rotational actuator
- Drive a stepper motor
- Drive initial versions of the actuators
- Design and make PCB to work with DRV8428
- Drive a stepper motor using DRV8428
Would be nice:
- Do some basic form of position detection on the linear actuator
- Do some basic from of position detection on the rotational actuator
- Communicate something over MQTT
- Drive a stepper motor over MQTT
I would say I was pretty successful this week, I have modeled and tested intial prototypes of both actuators! I have yet to drive a stepper motor with the DRV8428 but I have the completed PCB and it is just waiting to be tested. I want to move forward and improve the designs for both. For the linear actuator, I want to add caps to the plates so that they are sapced a fixed distance apart. I also want to build a housing for the motor so it doesn't extend out the back. For the rotational actuator, I want to try and shrink the size of the cycloidal drive and add bearings so that it is a much smoother motion. I would also like to try and begin experimenting with sensor feedback for each of the actuators
Week 9
This week is about molding and casting. I am planning on going away Saturday through Monday morning, so I will have to prep the design that I want to mold while I'm away
so I am able to cast it once I am back. The maker space on campus that I am a mentor in has a whole casting setup so I plan on doing all of the molding and casting there. I'm not
quite sure what it is that I want to cast though, perhpas it should be the cycloids for the cycloidal drive as they would likley have better structural/mechanical characteristics then
a 3D printed counter part.
Regarding forward progress on the final. I need to get a DRV8428 working this week and driving a stepper motor. I also wnat to get sensor feedback from both the magnetic encoders
and LiDAR. I also want to add a limit switch to the linear actuator to serve as a zero point. I can then use the lidar to measure the offset from taht limit switch and then define a modifier
and adjust all of the measurements with said modifier.
For the rotational actuator, I want to design a new version of the cycloidal drive that is smaller and uses bearings to reduce the friciton between the printed components.
Action Items for Week 9:
- Design a model use to create a mold
- Cast using the mold that I created
- Add caps and a motor housing to the linear actuator
- Add a limit switch and LiDAR ranging for linear actuator position detection
- Design a new Cycloidal Drive that is much smaller and uses bearings
- Experiment with the magnetic encoder
- Try to mount a magnet to the back of the stepper motor
Future Ideas
- Different size motors for the rotation actuators to provide more torque when needed
- Potentially different gear reduction components
- Design a closed loop stepper system with FOC
- Claw module