1. The document describes an expressive guitar robot with 7 degrees of freedom that is designed to convey different emotions through motion. 2. Different combinations of joint movements and functions were tested to create expressions like "Delightful", "Joy", and "Sad". 3. Inverse kinematics and geometry were used to maintain the end position while adding sine waves of varying scales and frequencies to different joints to produce life-like motions. 4. Future work includes integrating a more delicate strumming and picking mechanism.

1. X Arm: Guitar Robot
Ning Yang, Amit Rogel, Roger
Robinson
Jiahe Qian

2. RECAP - Motion Capture

3. Towards a more expressive robot
What makes a robot more human-like:
1. Have as many moving joints as possible
2. Small details / movement
3. Make sense / convey certain emotion
Constraint:
1. 7 degrees of freedom
2. Maintain end point in a steady plane

4. Method
Inverse Kinematics and Geometry:
● maintain the original end-joint position and facing angle

5. Method
Addition of Sine Waves:

6. Result
We tried:
● Different combination of joints used
● Different functions on how each joint moves
● Different initial starting position
● Different scale / frequency of movement

7. Expression 1: Delightful
j1_x = 0.25*sin(2*pi*Fc*t);
j2_x = 0.2*sin(4*pi*Fc*t);
j4_x = -asin(j1_x*d1/d2)-j1_x; %Geometry compensation for j1
j6_x_a = asin(j4_x*d2/d3); %Geometry compensation adjust for j4
j6_x_b = j1_x + j2_x +j4_x; %Angle compensation for j1, j2, j4
j6_x = scale* ( j6_x_a*(1-deep) +j6_x_b *deep) ; %Combine j6_x_a, j6_x_b

8. Expression2 : Joy
j1_x = 0.25*sin(2*pi*Fc*t);
j1_x = clip(j1_x,max,min); % Clip sine to create rest
j1_x = smooths(j1_x,’g’, stdev); % Gaussian smooth the sharp points
j3_x = -j1_x; % Movement cancel with j1_x
j4_x = 0.25*sin(2*pi*Fc*t);
j5_x = 0.15*sin(2*pi*Fc*t); % Little detail of shaking head
j6_x = 0.25*sin(2*pi*Fc*t + 0.25*pi) ; % Phase create follow through movement

9. Expression 3: Sad
j1_x = 0.05*sin(2*pi*Fc*t);
j2_x = 0.2*sin(2*pi*Fc*t*1.2);
j3_x = (1/5) * (sin(2*pi*Fc*t*0.8)+sin(7/3*2*pi*Fc*t*0.8)+sin(7*pi*Fc*t*0.8)); % Complex movement create hesitation
j5_x = -j3_x; % Cancel movement with j3_x
j6_x = 0.4*sin(2*pi*Fc*t*1.2+0.25*pi*1.2); % Phase create follow through

10. FUTURE
Future Project Work:
• Integration with more delicate strumming / picking
mechanism