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The mechanical parts of the hand are almost exclusively 3D printed with the Bambu Labs printers in TIW. Every linkage from every finger is printed in one go on the Bambu Labs printer. Some parts like the palm clamshell and the forearm clamshell were printed on the Raised3D FDM printers. The parts printed on Raise3D benefited from the higher-precision printing that Raise provided. Another benefit of the Raise3D printed parts is the ease of removal of the support structures on those parts.
Figure 1: Initial Failed Print of the Finger Linkages. Print failed due to temperature gradient on the print bed, causing one linkage to peel off the bed.
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There were 2 failures during the fabrication of the Robotic Arm, namely, during the printing of the finger linkage and forearm clamshell. Both failures were due to uneven build plate heating on the 3D printers. We also had to drill a hole in the linear actuator mount because the power line passthrough slot was accidentally removed during CAD revision.
Figure 2: Missing Linear Actuator Power Passthrough
Figure 3: Acrylic Top Plate Snapped in Half
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The wiring of these electronic components is shown below.
Figure 4: Circuit Testing. The initial circuit testing was done outside of the enclosure
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Media 1: Initial Mechanism Testing w/o Logic Controller: Testing mechanism and compliance without a logic controller or H-bridge
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Our code defined the H-bridge parameters to either send voltage from out3 or out4 to the linear actuator that dictates the direction of the linear translation of the linear actuator. Before sending out a signal, the voltage integer value was mapped from 0 to 255 to achieve a digital PWM signal and then it is sent to the H-bridge to run the actuator at a proportional rate as the value read from the joystick. We attached our code below.
Figure 5: Arduino Code for Robotic Hand
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Media 2: Functioning Prototype Fully Assembled