Group 10 – Helping Hand

Taylor JonesEric Donley

Kurt GrafMatt Carlson

OUR PROJECT IS• A Haptic Robotic Arm controlled by a sleeve mounted with motion

and force sensors on a human operator's arm – which controls the motion-tracking robotic arm's proportional motion.

These robots have a wide range of industrial and medical applications such as pick and place robots, surgical robots etc. They can be employed in places where precision and accuracy are required. Robots can also be employed where human hand cannot penetrate.

Theoretically, adding digits (fingers) to the arm with extremely fine control could make a skilled work duplication station possible.

That means you make a part at your workstation and the Helping Hand duplicates your work on a robotic station.

We are Electrical Engineers and a Computer Engineer candidates for Bachelor of Science in Engineering diplomas

Concern for real working world (industrial) knowledge and skills led the team to choose for senior design project a modern application of an industrial standard robotic application - the robotic arm.

Motivation for Project

PROJECT CONCEPTWhy study the human-operated robot arm?

The future of robotics in manufacturing and assembly is increasing flexibility both in mechanical performance and ubiquitous integration with human workers. The future of robotics is greater dexterity, easier and quicker programmability, and safe operation with human co-workers. Building a tele-operated master-slave robot arm driven by sensors worn on a human arm is investigating future possibilities and general performance considerations of advanced robotics.

Goals and Objectives of Our Project

1. Proportional motion-tracking of a human operator's arm motion

2. Fast tracking response = or < 0.1 seconds

3. Effective grasp-and-place 50 gram object with end-effector

4. Smooth and safe and stable motion

5. 6+1DOF with elbow and wrist roll

Specifications of Performance

1. Less than 0.1 second (human reaction time) delay from

human arm motion to robot arm motion-tracking response

1. Automatic reset to start position

3. Internal range-of-motion limitation fail-safes

4. Grasp, lift, and place 50 gram payload

5. End-effector does not damage payload

Not an Open Loop SystemExteroceptive (operator) Feedback

System Overview

AL5D Arm

• Length : 20 in.

• Gripper width : 1.25 in.

• Degree’s of freedom : 7

MPU-6000/6050 Six-Axis MEMS

MPU-6000/6050 Six-Axis (Gyro + Accelerometer) MEMS MotionTracking™ Devices

for Smart Phones, Tablets, and Wearable Sensors

Completed sensor board with 4x4x1 mm gyro

TWI Timing

• High >= 0.7*Vcc

• Low <= 0.3*Vcc

• tmax = 300ns

• V(0) = 0

• V(inf) = Vcc

• Vcc = Vc + I*R

• Vcc = Vc + R*C*dVc/dt

• dVc/dt + Vc/RC = Vcc/RC

• Vc = Vcc(1-e^(-t/RC))

TWI Timing

• 0.7*Vcc = Vcc*(1-e^(-t/RC))

• 0.7 = 1 – e^(-t/RC)

• -t = RC*ln(0.3)

• RC = -t/ln(0.3)

• t <= 300ns

• RC <= (300*10^(-9))/ln(0.3)

• RC <= 2.49*10^(-7)

GYRO EquationThe gyro gives data in

degrees/second To determine actual angle of

rotation requires integration with respect to time

∫dΘ dt = Θ

Mounted Sensors

Motor Choice

Microcontrollers

Name I/O pins Memory A/D converter PWM Language Price

Basic ATOM 24 2414k code368 RAM

256 EEPROM11 channels 3 channels BASIC $8.95

PICAXE-20X2 184k code

256 RAM11 channels 0 channels BASIC $3.88

ATxmega128A4U 34128k code8k SRAM

2k EEPROM12 channels 16 channels C or Assembly $3.00

Propeller 40 pin DIP 32

64k RAM/ROM

0 channels0 channels

Created in codeSpin $7.99

Operational Flow Chart

Software Flow

Main Loop-int main(void)

Sensor ControlVoid init_sensors(void)

Void init_twi(void)

Void read_sensors(void)

Void translate(accel_t_gyro_union, accel_t_gyro_union, accel_t_gyro_union)

Motor ControlVoid init_motors(void)

Void move_to_default(void)

Void move_motors(uin8_t[7])

IO controlVoid init_pins(void)

Math Functionsvoid getQuaternion(int16_t*,const uint8_t*)

void createQuaternion(Quaternion*,const uint8_t*)

void GetGravity(VectorFloat*,Quaternion*)

void GetYawPitchRoll(ypr,Quaternion*,VectorFloat*)

void loadBuffer(uint8_t*,accel_t_gyro_union)

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Motor Coordination• Base motor is controlled by the

yaw of the bicep sensor

• Shoulder motor is controlled by the pitch of the bicep sensor

• Elbow rotation is controlled by the roll of the forearm sensor

• Elbow motor is controlled by the yaw of the forearm sensor

• Wrist rotation is controlled by the roll of the hand sensor

• Wrist motor is controlled by the pitch of the hand sensor

• Grip motor is controlled by a button located on the finger

Sensor Data Conversion

TESTING

A plastic robot arm prototype was built and proved very useful for component acquisition. In particular, an arduino control board was used to initially test the gyro sensor boards and to test the servos after mounting them on the metal robot arm.

3 systems’ components required testing:

• 6-axis gyroscope-accelerometer sensors

• Digital and analog servo motors

• Microcontroller board

Testing Results• 7 servos plus two spares were tested out of the box – OK

• 7 servos plus two spares tested on robot arm – 5 OK

Base and shoulder servos aren’t strong enough

Base only rotates plus or minus 5 degrees

Shoulder only rotates 30 degrees

• 4 6-axis MPU-6050 gyro-accelerometers tested individually – OK

6-axis MPU-6050 gyro-accelerometers not tested in system

• 1 MCU built and tested unconnected to sensor-robot system – OK

MCU not tested in sensor-robot system

Power Supply

• Two different supplies are needed

• Microcontroller and sensors

• Rated at 3.3v

• Servos

• Rated at 6v

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Power Supply

• Initial plan• Battery Pack

• 6v

• Limitations • Current

New Plan

• Power plug through the wall

• Advantages

• Limitless power supply

• Configurable for high current

• Disadvantages

• Bulky

• Increase costs

• Use of transformer to step down the voltage from the wall to 6v

• Then rectify the voltage to DC

• Use of linear regulator to further drop the voltage to 3.3v

Combine 2 power supplies in one using a shared dc power bus and dc-to-dc regulator

Single PC 350 Watt P/S configured as a Shared DC Power Bus at 5 Volts for servos and dc-to-dc regulated to 3.3 Volts for sensors and micro-controller unit

PC 350 WP/S driving 18 amps at 5 volts

120V AC in

BaseServo

ShoulderelevationServo

Wrist/ForearmrotationServo

WristelevationServo

GripperServo MCU

GyroBicept

GyroForearm

GyroHand

5 Volts3.3 Volts

ElbowrotationServo

ElbowelevationServo

LD1117AV33

5V to 3.3V Voltage Regulator

Connection board

PC PowerSupply

Work Remaining to Complete Demo

1. Programming effectiveness between sensors, mcu, and servos tested and proven

2. Power supplies built, tested, implemented

3. Mechanical and electrical system performance documented

Budget