This week, we managed to complete the final iteration of our project despite the delays and difficulties we encountered. First and foremost, had to redesign and assemble a new superstructure for the robot, for the configuration for the legs on the older body did not offer enough stability to the robot. For instance, in the old configuration, all 4 feet were located slightly more forward on the craft, which could cause the robot to fall on its back more often. In the new leg positioning, however, the back legs were reversed to face backwards and the feet were moved towards the rear of the robot. As a result, it would theoretically offer much better stability to the robot when standing. In addition to the changes to the body of the robot, we also moved the location of the motors and the wheels they powered, which were brought much closer together than before. By doing so, however, we ran into a serious problem, for the wheels were too close to each other and would interfere with each other's movement. In order to solve this issue, we lengthened the distance between the motor and the spinning wheel on the two back legs. In doing so, we eliminated the issue that the wheels would affect each others' rotation. After some troubleshooting on the configuration, we moved on to designing locking mechanisms for the joints of the legs. We tested several methods for the locking mechanism. We found that in certain areas, it was easier to just put a screw across the axle, while in other areas, the use of wood glue was required. Despite the confusing nature of this process, we managed to complete it in time. Unfortunately, when it seemed that everything was going according to plan and that the final iteration was complete, we discovered with dismay that our walker could not stand. As a result, we plan in trying to fix this issue as soon as possible before the presentation of our project on December 3rd. If we are not able to solve the problem, we plan in putting it on a fixed transparent support above ground and only showcase the walking motion. (sad... ;( )
This week, we worked hard on the construction of our final iteration. First and foremost, we printed out the main body of our walker and assembled it using wood glue. In this final iteration, we also made a removable hatch that would be used to hide and protect the electronics located inside of the robot. Then, we moved onto the design of the legs and of the feet of our robot. Though the printing process was relatively easy, we had to adjust certain parameters of the walking mechanism and of the legs. One of the major issue we ran into was the fact that one of the connection shaft had to be bent in order for the wheel to fully complete a 360 degrees rotation. In order to solve this issue, we added a lengthened socket on one of the links of the walking mechanism. Furthermore, we also had to lock the motors onto the walls of the inside of the craft. While we could not find suitable nuts for the type of screw we needed (until after the problem was solved... ;( ), we used lock nuts to replace conventional nuts to attach the motors to the robot. In addition, we also had to cut out numerous shafts for the connections of the legs. As many of the connections required an unique length to fit in the leg, it was a perilous task to cut out and organize them. There were also a large amount of work required in preventing the different links of the legs and of the walking mechanism from colliding with each other. Despite the difficulties, we managed to create a specific layout that prevent the interference between each linkage. Next week, we plan in finishing the final iteration. We would continue working on the connections and we would test out the effectiveness at walking of our robot.
This week, we made some progress in building the third prototype of our legged walker and even managed Tom complete it this Friday. During this time, we made rather significant progress on the assembly of parts and improvement on the prototype. First, we successfully corrected the problems we encountered last week with the lengths of the legs and of the connection arms of the mechanism. For instance, we allocated more length to the connecting part of the lower leg of the walker. By doing so, we we managed to generate a walking motion through our walking mechanism. Furthermore, we also improved on parts of the body of our robot. For instance, we adapted the side of the body to be able to fit a motor onto it and refined the holes to better suit the screws that’s hold the leg on place. In addition to mechanical improvements to our walking mechanism, we have also started to work on the electronic parts of our robot. For instance, we received a tutorial on how to connect a motor shield to an Arduino. We also started on the connection between the Arduino and the remote controller. Due to the lack of time however, we were unable to make significant progress. Next week, we plan in working faster and complete the already designed dans body of the robot. Then, if everything goes according to plan, we would move on to the electronic parts.
This week, we worked on the construction of the third prototype of our walker. Firstly, we decided use wood as the building material of this iteration. We also decided to implement the walking mechanism into this prototype. Furthermore, we also tried to attach the walking mechanism to a D.C. motor in order to test out the validity of the system. In addition to the motor, we also printed out mock-up legs that were meant to test the dimension of the legs and to prove the validity of the dimensions of our walking mechanism when attached to the legs. Finally, my partner also started on connected the motor to an Arduino in preparation for remote control of the motors. Unfortunately, the dimensions we started with were too short. Moreover, we realized we would have to build a horizontal platform for the motor to stay upstraight. Next week, we plan to complete this third prototype and move to building out final iteration.
With the feedback we received from last week’s presentations, we decided it was time to print out the walking mechanism for our robot and to test it out. First, we had to choose between several concepts of walking mechanism. One of them, for instance, relied on only one connection to the powered wheel, while another design proposed to have two points of attachments with one connected to the powered wheel and the other rooted onto the craft itself. After some reflection over the matter, we decided that it would be more adequate to use the latter design. We modeled it in Rhinos and cut it out of wood using the laser cutter. Then, we temporarily screwed all of the cut pieces together and tested the validity of the mechanism. After several trials, we deemed the design to be adequate enough for our legged walker. During this week’s courses, we also decided to change our four legged walker into a six-legged walker. We decided to do so because we were worried about the stability of the robot when in motion. For instance, when a six legged walker is in motion, there is always three legs that are in contact with the ground, forming a stable triangular support for the robot to remain up straight. Furthermore, we also decided to simplify the leg design by employing only one for all six legs. This would alleviate our design and building process do give us more time to test the walker’s performance. Finally, we also thought about how the robot would turn. One of the Solution we came up with consisted of putting servos immediately above the feet of the walker robot. When the robot is in motion and three of its legs are lifted, we can then Use the servos to rotate the craft on the spot. In next week’s periods, we will continue to experiment with the walking mechanism and will further explore how to control the DC motors with a remote controller.
Today, we gave a presentation on the current progress of our project and received feedback on the current stage of our legged walker. According to the nuvu coaches, the rate at which our process of designing is good. Furthermore, we received positive feedback on our initial sketches and ideas. After our presentation, we were given a numbers of advices for what should be done in the near future. For instance, it was proposed that we should not linger with simulation of gears in fusion 360 and that we should print out the whole mechanism as soon as possible. In addition, it was proposed that we should start with building only one leg and make the final product slightly lower and wider.
In future periods, I intent to apply these propositions. Depending on the time left for our project, we would make two separate leg designs for the front and rear leg or we would only copy and paste one single leg design for all four legs of our walker. Overall, today’s nuvu class was very useful in giving us a clearer vision of the future of our project.