Dual Robot Log Handling

The goal of the project is to design end effectors and program two 6-axis robots to pick up, rotate, and manipulate a log through a band saw to cut a log into a cant. The end effectors will bolt to the 6th axis of each robot and secure the log by penetrating the wood at each end. The cutting planes for each log will be determined by an optimized scan and communicated to the robots via a Programmable Logic controller. In the first year of the project, our goal is to complete the end effector design and program the robots to cut a single face of the cant.

=Project Value= In modern sawmills, logs are cut into lumber through a massive automated assembly line of hydraulic equipment, which is expensive to maintain and requires extensive computing power. This could be replaced by a two-robot system which can cut logs with greater efficiency and reduced overhead, maintenance, and computing costs.

=Product Requirements=

=End Effector= The biggest challenges in the end effector design is implementing shock absorption along the log longitudinal axis without compromising bending under the gravity load of the log and while remaining within the strict size requirements. We constructed a rapid prototype to test the shock absorption method of mounting compression springs around the mounting bolts. This design would require 2 plates with the springs located in between each plate. The prototype can be seen below. After fabricating the spikes and test fixture, we no longer had access to the university's load frame machine due to the outbreak of COVID-19. Since we were not able to obtain these test results, we needed a new method to select spike tip geometry and compression springs. Idaho Forest Group had pre-manufactured spikes which we decided to incorporate in our design. We found research online regarding the force required to extract a nail from wood, and we used this model for spring selection. This led us to find a list of 6 springs which could fit within the housing member, withstand the maximum expected force, and deflect approximately 0.25 - 0.5 inches. Any of these springs will be suitable for our final design, which can bee seen below.
 * Rapid Prototyping :
 * Design Solution :
 * End Effector Spike Penetration Testing :
 * End Effector Spike Geometry :
 * End Effector Design :


 * End Effector Spike Geometry :

After fabricating the spikes and test fixture, we no longer had access to the university's load frame machine due to the outbreak of COVID-19. Since we were not able to obtain these test results, we needed a new method to select spike tip geometry and compression springs. Idaho Forest Group had pre-manufactured spikes which we decided to incorporate in our design. We found research online regarding the force required to extract a nail from wood, and we used this model for spring selection. This led us to find a list of 6 springs which could fit within the housing member, withstand the maximum expected force, and deflect approximately 0.25 - 0.5 inches. Any of these springs will be suitable for our final design, which can bee seen below. As seen in the images below, the end effector bolts to the end of each robot. Each end effector grips one end of the log as the robots maneuver the log through the cutting paths.
 * End Effector - Robot Interfacing :

=PLC Programming= The PLC's role is to communicate data from an optimizer to the robots. Prior to reaching the robots, each log is scanned by an optimizer which generates unique cutting paths to maximize the economic value of each log. For each log, we need the following parameters: length, angular orientation, and height at each end. The PLC will receive these variables as each log is scanned, convert them to coincide with the robot coordinate system, and output them to the robots.

=Robot Simulation= In order to perform move each log through unique cutting planes for each log, the robots need to be able to receive the PLC data and automatically account for log geometry. This requires a baseline program which cuts one face of a perfectly cylindrical, infinitesimal log. Embedded in the program are offsets which become filled by optimizer data for each log via the PLC. With these offsets, the robots can perform the following motions to cut a log into a cant.

=Human Machine Interface= The purpose of the HMI is for an operator to interact with the robotic system to ensure the operation is running smoothly and act accordingly if it is not. The operator will also be physically watching the system to detect any potential safety concerns or operational errors.

=Design Validation= All design validation testing is to be completed at the automation facility in Athol, ID. Due to COVID-19 and time constraints, our team was not able to travel to the facility. Our clients with Idaho Forest Group will need to perform all onsite testing as they continue into the next phases of the project. The two areas needing validation are the mechanical design of the end effector and the system software integration. To implement the end effector into the robotic system, the fist step is to calibrate the tool center point. This will be done by mounting the end effectors to each robot, screwing in the calibration rod, and moving each robot so the rod is touching the saw blade where the logs will be cut. Then, these robot positions will act as the geometric origin for the robots. Once the end effector is calibrated, the shock absorption mechanism needs to be verified. This will be done by programming the robots to drive the spikes into each end of a log and lift up. If the robots do not detect a collision and shut down in the process, then the shock absorption mechanism is working as designed. lastly, the end effector should be able to maintain the log securely as the robots perform basic linear motions. To verify the end effector grip, Our clients should program these basic motions, run the program, and (when the robots are stationary) grab the log and attempt to move it. If all goes well, the log should not move significantly as a human applies loading. Once the end effectors are mounted, and their design is verified for operation, the system software integration can be tested. The operator (one of us) will input the appropriate log dimensions into the HMI to communicate with the PLC. Then, the PLC should send the data to the robot Teach Pendant, and the robots should maneuver the log to cut a single face with the saw blade.

=Team Members=

=Additional Documentation=


 * Schedule
 * Budget
 * Team Contract
 * PLC Training
 * End Effector Alignment Rapid Prototype Drawing Package
 * End Effector Drawing Package