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Balance Bot DT04 Stephan Baranoff Nicole Beck Chris Hamrock Stephanie Kosec Dr. Sastry

Balance Bot DT04 Stephan Baranoff Nicole Beck Chris Hamrock Stephanie Kosec Dr. Sastry. Introduction. The Statement of Need A remote controlled or autonomous robot that can traverse an obstacle course and be useful for applications such as search and rescue, military, ….

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Balance Bot DT04 Stephan Baranoff Nicole Beck Chris Hamrock Stephanie Kosec Dr. Sastry

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  1. Balance Bot DT04 Stephan Baranoff Nicole Beck Chris Hamrock Stephanie Kosec Dr. Sastry

  2. Introduction The Statement of NeedA remote controlled or autonomous robot that can traverse an obstacle course and be useful for applications such as search and rescue, military, …

  3. Introduction The Design Problem Definition The Design GoalA two wheeled remote controlled robot – with that can maintain its balance without any external support.ObjectivesTo complete a predetermined obstacle course in the shortest amount of time, while maintaining balance. Constraints Weight does not exceed 50lbs, its size does not exceed 3’x 3’x 3’. It cannot use an internal or external combustion engine and cannot cause environment damage.

  4. Design Requirements Specification Mechanical • With zero inputs (no velocity or turning request, no external applied force) in steady state the robot shall: • S1: Not vary more than 3 degrees from vertical • S2: Not drift more than 6 inches from the the original position • From an initial condition of zero linear speed on a level surface, the robot shall: • S3: Be able to recover to 0 degrees, measured from vertical, starting at an angle of no more than 30 degrees, measured from vertical. • On a smooth level surface, the robot shall: • S4: Have a linear velocity of no less than 48 inches/s • From a lateral velocity of 48 inches/s, on a smooth level surface, given a step input request to zero speed, the robot shall: • S5: Stop within 6 inches of the step input • S6: Not vary more than 5 degrees from vertical during the transient stopping period • S7: Not move in the opposite direction of the original forward motion by more than 6 inches from the location where the zero input was received. • From a constant velocity state the robot shall: • S8: Be able to climb and descend ramps having no more than a 20 degree incline with less than a 6 inch/s change in velocity. • When transitioning between surfaces (coefficient of friction having a step change) at a constant velocity the robot shall: • S9: Not exhibit a change in velocity of more than 6 inch/s. Control • C1: The control systems for the robot will be implemented as discrete time-domain equations on a digital computing and logic system.

  5. Design Requirements Specification Electrical • EL1: The angular position sensor will be able to detect the angle of tilt of the robot within 1 degree of the actual angle. • EL2: The angular rate sensor will be able to detect the angular velocity of the robot relative to vertical within 0.1 degrees/s. • EL3: The processors and digital logic subsystems will be capable of executing the required control algorithms and digital filter calculations at no less than 50 times the maximum bandwidth of the input to the filter. Power • P1: The motor driver will be capable of operating at a supply voltage of no less than 24 volts DC and no more than 48 volts DC. • P2: The motor driver will be capable of supplying no less than 30 amps DC of peak current. • P3: The motor driver will be capable of supplying no less than 15 amps DC of continuous current. • P4: The motor will be able to supply maximum peak stall torque with an input current of no more than 30 amps DC. • P5: The motor will be able to supply maximum continuous power with an input current of no more than 15 amps DC. • P6: The motor and motor driver will be capable of handling transient loads of full peak current and produce the rated peak stall torque of the motor in less than 100ms. • P7: The energy storage system supplying the motors and drivers will be capable of operating at 1 CA of current load for 1 hour. • P8: The energy storage system will be able to be recharged from 30% charge to 70% charge in under 4 hours. Ergonomic • ER1: There will be 2 emergency stop buttons, one on the Balance Bot and one on the Remote Control • ER2: The Balance Bot will safely stop all operation in no more than 2 s of either of the emergency stop buttons being pressed. Economic • EC: The parts required to build a prototype of the Balance Bot will cost less than $625.00.

  6. Engineering Calculations Electrical

  7. Engineering Calculations Power

  8. Engineering Calculations Control

  9. Engineering Calculations Mechanical

  10. Engineering Calculations Ergonomic

  11. Engineering Calculations Economic: • SD $100/person • Honors Program $75/person • 3 members in Honors Program • Total Budget: $625

  12. Hardware Block Diagram Non-volatile Memory Driver Inputs Gyroscope Wireless Transceiver ESTOP Input Accelerometer μController IR Sensor IR Sensor Current Sense Amplifier MOSFET Driver Circuit MOSFET Driver Circuit Current Sense Amplifier DC/DC Converter Current Sense Resistor H-BRIDGE H-BRIDGE Current Sense Resistor Encoder Encoder Battery Left PM DC Gear Motor Right PM DC Gear Motor Battery Battery Left Wheel Right Wheel Accepted Technical Design Hardware Theory of Operation -describe how the major hardware design blocks go together

  13. Accepted Technical Design Discuss the progression of the design from level 0 to level n+1 • The hardware block diagram began with an microprocessor, a battery, a motor, wheels and a transceiver. From there it was decided that two motors were needed to independently control the wheels. In order to control the motor, a motor control circuit would need to be designed for each motor. Part of the motor control includes an H-bridge which will allow the robot to move both forward and backward. The H-bridge will supply the current to the motor and in order to control the amount of current going to the motor, the current sense amplifiers and current sensor resistors were added to the design. Also, since the H-bridge is controlled by a PWM signal, the MOSFET driver circuits were added to amplify the signal. PMDC gear motors with a 10:1 gear ratio were chosen in order to develop enough torque to move the Balance Bot.   • Once the method of movement of the robot was determined, the control of the movement needed to be determined. It was decided that sensors would be added to accomplish this task. An accelerometer, gyroscope, and infrared sensors were specifically chosen to send the Balance Bot’s position signals back to the microprocessor. • In order to power the robot, separate batteries would be needed for the motors and the microprocessor. To ensure that the microprocessor receives the correct input voltage, a DC/DC converter was added to the output of the battery to regulate it. • From the transceiver we added the signals that would be sent to the microprocessor. These signals include the driver inputs and the ESTOP. For debugging and error logging purposes, a non volatile memory was added. Lastly, in order to meet competition guidelines as well as for safety, we added an additional ESTOP to the Balance Bot.

  14. Accepted Technical Design Software Theory of Operation -describe how the major software design blocks go together

  15. Accepted Technical Design Discuss the progression of the design from level 0 to level n+1 • The first software block diagram developed included inputs from sensors, processing, and outputs to actuators. This generic system expanded as the hardware system components and requirements were addressed. The first piece of software added was a simple motor control interface that would transform a torque number within the software into a useful output readable by a motor controller. Once the motor controller design was added to the parts to be designed, that block was changed to include the motor control algorithms and digital logic. • Sensors were the next logical piece of hardware added to the system. The sensors needed to measure a variety of physical parameters identified as important for the Balance Bot, but the output format from the sensors was not yet known. Multiple sensors were deemed necessary so a fusion of sensors became necessary. This block is a discrete time filter of some kind that was added to the system to support multiple sensors. • The output of each sensor is not yet known, which inspired the addition of a device driver block to the software. The output of sensors usually needs to be calibrated and adjusted in some format to calculate a physical value, velocity for example, from a sensor output, such as ADC counts. A calculation of physical value from raw value software block was added for each component after the device drivers. • Between the input sensors and the output actuators is the compensator that calculates the next output based on current inputs. Feedback from motors was added to the system and signals were routed between blocks to improve data flow accuracy. Safety and watchdog functionality was added in order to support debugging of the software system. This allows for both data logging for anomalous event root cause analysis as well as model parameter fitting. At this point, the software block diagrams were deemed complete for this level of design.

  16. Major functions Major functions

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