MSE312 One Degree of Freedom Pick and Place Robot

The MSE312 term project required teams to design, build and control a pick and place arm to rotate 180◦ pick up a metal puck and rotate 90◦ to drop the target. Mechanical design, electrical and protection circuitry, control system and integration aspects were designed and evaluated for the ultimate goal of the system to perform the required task in the fastest time possible while being robust and reliable.

The mechanical truss arm was constructed using brass rods under project constraints and concep- tualized around minimizing mass moment of inertia, centre of mass close to the axis of rotation and minimal deflection under FEA analysis. Concept selection analysis was performed to appropriately select the final mechanical design. The electronics design consisted of motor circuit drive, electromagnet circuitry, power protection and configuration setup with the apparatus limit switches. The electrical configuration provided a soldered circuit board for 12V power to the system and compatibility with 5V signal which would be used for the PWM control signal of the DC motor and electromagnet. The initial control design evaluated electrical/mechanical system continuous time transfer function which was used to plot the system root locus and evaluate PID controller parameters. Integrating the system with a digital micro controller the system is need take into consideration the Z-domain therefore PID value were tuned to operate with the set sampling period. In integration of the sys- tem using the micro-controller was inter-phased using Simulink. The logic of the control program conceptually used a finite state machine for correct sequential operation of the system. Using the integration of the program final PID values were tuned to two individual sets for each 180◦ and 90◦. The final system performance demonstrated accurate pick and place in a avg. run time of 2.03s with a over damped system response. Designing the system to be over damped was critical as an over- shooting system with varying momentum in the system resulted in unpredictable overshoot values. Attaining close to critical damping response by tuning the system, the motor current flowed in one direction for one interval of travel.

The system was assessed for further improvements on mechanical, electrical, controls and integration subsections to order to evaluate aspects of improvement for the system for further improvements in future similar projects and considerations for integrating a control system.

The full documentation for this project is given here: MSE312 Documentation