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Senior Design Project Data Sheet Project # 13212 Start Term 2012-1 Project Name Colisionless Rimless Wheel (Wireless) Team Guide Les Moore Project Track Vehicle Systems Project Family Collisionless Rimless Wheel Project Sponsor FEAD grant Doc. Revision 1.00 Project Description Deliverables: 9. Project Background: We aim to construct the most energy-efficient, four spoke rimless wheel that can sustain periodic motion. This project will help understand how to evolve robot movement because our end product will demonstrate continuous collision-less motion by eliminating energy loss between the feet (in this case spokes) and the ground, which is currently the primary source of inefficiency in walking robots. Dr. Gomes’ unpowered 5 spoke rimless wheel demonstrates edges walking on a flat surface with periodic rotating motion and energy loss as a wheel. We will be using Gomes’s existing model to help understand and achieve our goals. It is also observed that high interest in walking robots exists and therefore previous research has tried to achieve a similar end goal as ours. For example there exists a robot that elegantly mimics human motion [IEE Link] also a BMW sponsored project walks on multiple legs solely powered by wind [Website Link]. However, in these devices and all other similar research, the energy loss from transport is either unknown or very high. Hence the findings and outcomes from our research will help improve current understanding and future application of walking robots. 10. 11. 12. 13. 14. 15. 16. Expected Project Benefits: 1. Problem Statement: Currently the primary source of inefficiency in walking robots is energy loss from the impact between the foot and the ground which dramatically increases the cost of transportation (COT). Our projects aims to demonstrate an alternative walking motion that minimizes the energy loss normally present in bipedal robot motion by means of a Collisionless rimless wheel, which stores mechanical energy between each collision, thus minimizing COT, and extending the device’s range. Objectives/Scope: 1. 2. 3. 4. 5. 6. 7. 8. Four Spoke Collisionless rimless wheel capable of "walking” across level ground (25 steps) Minimal total energy use (<= .1 COT) Wireless data acquisition for all trials (at least 3 meter range) Timely Ability to control parameters while in motion (Data sampling rate of at least 100Hz) On board data storage (.1 hours) Precise data set includes for both inertia and rimless wheel: o Angular acceleration o Relative angular position between inertial wheel and rimless wheel Use of actuator power (electric motor) to maintain movement Easy and safe to use Fully functional Collisionless rimless wheel that meets the project objectives and customer needs. Documented set of experimental results for 50 repeated trials of 25 steps each. MFG and Assembly documentation: how to fabricate the prototype Videos showing successful “walking” of 25 steps. A <2min video explaining the project to the general public A video operation guide to running the device and changing parameters. Complete sets of raw data (time, angles, ang. velocities) for all trials showing periodic motion of state variables as well as total electrical power use as a function of time for a minimum of 25 steady state cycles. Well-written operation/maintenance manual (device operation, data collection, algorithm modification, etc.) 2. 3. Delivery of a fully functioning, four spoke Collisionless rimless wheel, that is pre-loaded manually and is then able to “walk” independently without any assistance other than its integrated electric motor. Motor control settings can be modified on the fly while system is in motion, thanks to wireless data transmission. Improve current understanding and future application of walking robots Core Team Members: Jeremy Benn (ME) Jason Bowerman (EE) Phil Buchling (ME) Robert DeWitte (EE) Madhur Jain (EE - Team Leader) Senior Design Project Data Sheet Strategy & Approach Assumptions & Constraints: 1. Assume all collisions with the ground are completely inelastic. 2. Assume no slipping between feet of spokes and ground for calculations. 3. Assume air resistance to be negligible for the size of our device, and its relatively low speed of travel. 4. Constrained by weight of device relative to size. Excess weight of the structure will lead to higher COT. 5. Constrained to minimum of 25 “steps” of travel on level ground, in at least 50 trials. 6. Constrained by the need of additional actuation (e.g. electric motor) to fulfill range constraint. 7. Space constraint for mounting sensor and control electronics. Ideally mounted around axle hubs of wheel. 8. Constrained to wireless transmission of sensor data and motor control data. 9. Constrained by budget. Overall cost cannot exceed $900.00. 10. Can be inspired by previous unpowered rimless wheel, but must build our own hardware test bed. 11. Assume all electrical Electrical can perform both individually and together as per available specifications. 12. Assume initial condition is always met. Issues & Risks: 1. 2. 3. 4. 5. 6. 7. Designing a rigid structure that is able to withstand the high stresses associated with energy transfer through the torsion spring and the electric motor. Maximum rigidity = reduced energy losses in system due to deformation. Sizing and relative rotational inertias of the inertial wheel and the spoke structure. Implementation of power transmission from batteries to various electronics and electric motor. Tolerancing and assembly of the two halves of the spoke structure to ensure correct assembly is possible. Mounting electronic components on wheel hubs such that weight is evenly distributed and as close to the center of mass as possible - i.e. Minimize rotational inertia of rimless wheel. Maximizing rotational inertia of inertial wheel: Ballast weight at outer rim -> rim-mounted batteries. Interfacing all electrical components to communicate with each other (Coding and wiring)