Fig. 1 Hybrid 3D printer scheme of the functioning hypothesis output value generated by the encoder for the feedback con- trol (constant duty pulses with variable period). Figure 4 shows an example of 8 short-stroke start-ups (blue curve) alternating with 8 fast-return movements (red curve) and rel- ative carriage speeds (green curve). Fig.4 Moving average for 50 cycles of duty and speeds for 5 print movements from end-to-end running alternating to 5 fast return movements anc relative encoder signal Fig. 6 Mathematical model scheme to relate the input signals to the output signals for interface | Fig.8 Functioning flow chart diagram of the controller for interface 2 Fig.9 a Arduino Mega 2560 controller; b RAMPS card; e A4988 driver Fig.10 Chip all-in-one Marvell 88PAAXOI control card of the HP DeskJet 1010; a front; b back; e Encoder pin connection Fig.11 Pulley, toothed belt, and HP DeskJet 1010 printer carriage Fig. 12 Signal acquisition scheme to acquire signals generated by the all-in-one chip logic board of the 2D printer Marvell 88PAAX01 with the Arduino Mega 2560 electronic card Fig. 13 Duration of the high pulse signal in carriage movements during printing (line (a)) and fast return (line (b)) (\vs) the active state of the control pulses with respect to the speeds obtainable by the reading of encoder values is therefore cali- brated the values of the constants by experimentally finding. For the printing movement: a = 0.1;b = 2;c = 1.04; f = were obtained for successive approximations of the param- eters present in the mathematical equations in order to fit as much as possible the curve obtained from the models with the original one. The mathematical model developed to bind Fig. 15 Pulse duration for the command of the carriage, Speed values during printing (and fast return) phases, speeds estimated by the model for fast-return and printing phases Fig. 17 Pulse frequencies (line (a)) and torque values (line (b)) when changing the pulley diameter D —0.11; g = 1.8; h = 1.0197; 1 = 0.128; m = 0.66, with the following model (Fig. 15): Fig.18 Overall design and control system of DC motors based on: Arduino mega 2560 (a); DC motor control driver for L298N (b) HP CB760-60030 motor, (¢), RAMPS card (d) connection with optical position encoder (s) As a first test, manual control is used to send some movement commands in the directions —X and +X. The first verifi- cation involved the good functioning of the system, which Fig. 19 Trace corresponding to a 50mm displacement Fig.20 Simulation of workpiece fabrication using Repetier-host
