The main objective of this research work is to develop a simulation procedure for modeling the soil-tool interaction for a blade of arbitrary shape. The primary motivation for this study is developing agricultural robots with limited power and pulling force to help farmers in crop production. In this thesis, a finite element (FE) investigation of soil-blade interaction is presented. The soil is considered as an elastic-plastic material with the non-associated Drucker-Prager constitutive law. A separation procedure to model the cutting of soil and a method of calculating the forces acting on the blade are proposed and discussed in detail. The procedure uses a separation criterion that becomes active at consecutive nodes on the predefined separation surfaces. In order to mimic soil-blade sliding and soil-soil cutting phenomena contact elements with different properties are applied. To verify correctness of the FE model developed and the procedures used, the FE results are first compared with analytical results available for straight rectangular blades from classical soil mechanics theories; and then the FE results are compared with the experimental ones. Also the effects of blade width, depth and rake angle on blade’s draft force were studied by simulating soil-blade interaction with different blade’s dimensions. After the analytical and experimental validation of the results for straight rectangular blade, the rectangular curved shape blade was modeled in order to investigate the effects of changing the blade’s radius of curvature on the blade’s draft force. The soil interaction with straight triangular blade in different rake angles was simulated next. Since the analytical solutions are limited to rectangular blades, calculated draft forces for triangular blade were verified only experimentally. The triangular and rectangular blades with the same width and depth of interaction were also investigated. The results showed that triangular blade draft force is around half of the amount of force acting on the rectangular blade with the same rake angle. Also the effect of triangular blade’s sharpness and changing the blade’s radius of curvature on draft force was discussed. By changing the blade’s sharpness, the draft forces of triangular blade were calculated in two conditions of constant blade’s width and constant blade’s contact length. The approach presented in this thesis can be used to investigate the soil-tool interactions for real and more complex blade geometries and soil conditions, and ultimately for improving design of blades to be used in tillage operations.

A fully instrumented on-water sprint canoe system was designed, built, and tested. The system consists of: one 6-axis load cell in the paddle shaft at the blade, one inertial measuring unit (IMU) on the paddle, one IMU on the boat, and one GPS unit on the canoe boat. These sensors communicated wirelessly to a laptop where the data was processed and displayed in real-time. The sensors were rigorously tested and well-measured in their satisfactory accuracy. The system can provide a full decomposition of the blade water force into propulsive (forward/aft), side, and vertical forces. Previous systems for canoe have been extremely simple and rudimentary. There has been more effort in the rowing and kayak systems but they still failed to capture a full force profile. On-water tests with national-level athletes examined a wide variety of sprint canoe strokes at different paces, power inputs, rates, and stroke lengths. The measurement system could clearly see the differences in force profiles between the stroke sets. A number of efficiency measures were developed using the available data. Instantaneous and integral in-stroke force ratios were developed based on the blade's propulsive force to total force proportion. Derived stroke averaged efficiencies also provided more information. These produced measurements of energy/impulse input to the boat's propulsion output. Differences in such efficiencies could be clearly seen in the various collected stroke sets. This system will be highly useful to high performance athletes and coaches for modifying athlete technique. It has potential for improving equipment design and matching athletes to optimal blade styles. More academically, it can assist biomechanical assessments of sprint canoe and numerical flow studies around blades. / Thesis / Master of Applied Science (MASc) / A measurement system for a sprint canoe paddle was created that can evaluate an athlete's stroke performance during race-like conditions. This system was tested using national-level athletes in a true on-water setting. By measuring the force and orientation of the athlete's strokes, the system was able to clearly distinguish the performance of various stroke techniques. Analysis of the force profiles and the derivation of stroke efficiencies provided additional performance indicators. This is the first system to achieve this amount of measurement detail of any rowing or paddling sport. This fully instrumented paddle system is ready to be used as a coaching tool to improve athlete performance. It can also be used as an academic tool for paddle blade study.