Final prj12

Group12: Hopping Robot: 

Group12: Hopping Robot Ken Ballaao Fred Grigoryan Daniel Pepa Anh Le Cameron Wiley Sponsor: Nathan Delson MAE Department UCSD ECE 191 Spring 2003 Professor Clark Guest Professor Pankaj Das

Presentation Agenda: 

Presentation Agenda Introduction to RoboPogo Background Parts Power Supply Wireless Control Balancing Control PC Board Development

Background: 

Background The use of mobile robots is increasing rapidly Can be sent into hazardous environments have homeland defense applications There are wheeled and tracked robots Legged robots Can go where wheeled and tracked robots cannot Move slowly Fast hopping robots The prototype will be a remote controlled pogo stick The name of the project and robot is “RoboPogo”

RoboPogo Parts: 

RoboPogo Parts Air Muscle Air Valve Sensors Power Supply Micro-controller Wireless Remote Control Stabilizing System

Air Muscle: 

Air Muscle The Air Muscle consists of a rubber tube covered in tough plastic netting which shortens in length like a human muscle when inflated with compressed air at low pressure. An Air Muscle has a power-to-weight ratio as high as 400:1, vastly outperforming both pneumatic cylinders and DC motors that can attain a ratio of only about 16:1.

Air Valve: 

Air Valve Festo Valve Fast switching Requires 24VDC at 1A current

Sensors: 

Sensors Gyroscope Measures the angular velocity of the robot Accelerometer Judges the amount of tilt from the robot’s upright position Contact sensor Determines when the robot touches the ground and when the valve should release the air muscle.

Micro-controller: 

Micro-controller MPC555 40MHz Floating point operations Inputs(for Hopping Robot) Analog from Gyroscope/Accelerometer Digital from contact sensor Pulse width from remote control Outputs(for Hopping Robot) Pulse width for stabilizing servos Digital for air valve

Power Supply: 

Objective: Need a portable power supply that will allow the robot to move free of wires. Air valve requires 24volts at 1amp in quick bursts. Microprocessor requires 5V. Wireless Controller Receiver requires 5V. Balancing Servos require 5V Results: Air Muscle Valve Step-up Converter to make 9v to 28v.(reducing the weight) RC Circuit to produce quick bursts of 1amp. Others 5 Volt Voltage Regulator for 5V supply. Power Supply

Step Up Converter: 

Step Up Converter

RC Circuit: 

RC Circuit

Wireless Control: 

Wireless Control Objective: Allow wireless control of the robot through integration with the MPC555 Microprocessor. Remote Control Transmitter Four channels available. Four channels for controlling… Start and Stop of hopping. Height of Hop. Turning of robot. Movement forward/backward.

Slide13: 

1. Control of Start and Stop of the hop Ø      The concept behind the start and stop code is the following: The robot has a contact sensor, that when it touches the ground it signals the robot to hop. Using a channel of the wireless controller, we will only allow the robot to hop when the PWM Signal is above a certain threshold. This is accomplished in Simulink using a Pulse Width Measurement Block, a Digital Input Block, a Digital Output Block, and a Stateflow Logic Chart.

Slide14: 

If the robot is on the ground and the PWM of the controller is above the threshold of 1.5ms, the Digital Output(Vout) will be high. This will activate the air muscle valve and the robot starts hopping. Else, the robot will not hop. Chart

Slide15: 

2. Control of Height of the Hop. Ø      This will be controlled by using the Wireless Controller to control the amount of delay given to the Hopping Robot while hopping. Therefore the delay variable will be an input from a channel from the Wireless Controller’s Receiver. 3. Control of Forward and Backward Movement. Ø      This will require the completion of the Balancing Control of the Hopping Robot. 4. Control of Turning.  Ø      This will also require the completion of the Balancing Control of the Hopping Robot.

Balancing Control: 

Balancing Control Operation: The gyroscope detects velocity change from the tilting robot The servos move attached arms to re-stabilize the structure. This continues until the accelerometer measures that the structure is level.

Balancing Algorithm(Reupert): 

Balancing Algorithm(Reupert) sm_command = K(desired -  actual) + sm_current rp ~ from potentiometer. der_rp ~ from gyroscope. sm_current ~ pot. in the servo. sm_command ~ pwm output to servo.

Slide18: 

 desired = - K p( rp -  rp_desired) – Kv( der_rp) Kv ~ Constant gain on position. To be determined through testing. Kp ~ Constant gain on velocity. To be determined through testing.

Slide19: 

Includes Gyroscope, Accelerometer, microprocessor, Darlington Array, RC and Step-Up converter circuits. Put together with wire wrap on PCB PC Board Development

Summary: 

Summary Power Supply Completed portable power supply Includes 9V battery, Set-up Converter, and RC Circuit Balancing Control Code is operational. Inputs are being translated into movement of balancing arms. Additional testing is needed to complete the balancing control. Wireless Control Wireless Controller is able to control the start and stop of the hop. Forward/ Reverse and Turning requires a completed balancing control. Circuit Development Used wire wrap to construct a custom board that will be mounted to the robot. The board contains the power supply circuit, the gyroscope, the accelerometer, and the Darlington array. Still need to mount the microprocessor.