Sridevi Kaza
nov 18th
Dependencies: Bezier_Traj_Follower_Example ExperimentServer QEI_pmw MotorShield
Diff: main.cpp
- Revision:
- 16:f9ea2b2d410f
- Parent:
- 15:495333b2ccf1
- Child:
- 17:1bb5aa45826e
--- a/main.cpp Thu Aug 27 14:55:58 2020 +0000
+++ b/main.cpp Thu Sep 24 20:16:05 2020 +0000
@@ -3,13 +3,18 @@
#include "EthernetInterface.h"
#include "ExperimentServer.h"
#include "QEI.h"
+#include "BezierCurve.h"
#include "MotorShield.h"
#include "HardwareSetup.h"
-#define NUM_INPUTS 2
-#define NUM_OUTPUTS 4
+#define BEZIER_ORDER_FOOT 7
+#define NUM_INPUTS (12 + 2*(BEZIER_ORDER_FOOT+1) + 2*(BEZIER_ORDER_CURRENT+1) )
+#define NUM_OUTPUTS 19
+#define PULSE_TO_RAD (2.0f*3.14159f / 1200.0f)
+
+// Initializations
Serial pc(USBTX, USBRX); // USB Serial Terminal
ExperimentServer server; // Object that lets us communicate with MATLAB
Timer t; // Timer to measure elapsed time of experiment
@@ -20,6 +25,110 @@
QEI encoderD(PD_12, PD_13, NC, 1200, QEI::X4_ENCODING);// MOTOR D ENCODER (no index, 1200 counts/rev, Quadrature encoding)
MotorShield motorShield(12000); //initialize the motor shield with a period of 12000 ticks or ~20kHZ
+Ticker currentLoop;
+
+// Variables for q1
+float current1;
+float current_des1 = 0;
+float prev_current_des1 = 0;
+float current_int1 = 0;
+float angle1;
+float angle_des1;
+float velocity1;
+float velocity_des1;
+float duty_cycle1;
+float angle1_init;
+
+// Variables for q2
+float current2;
+float current_des2 = 0;
+float prev_current_des2 = 0;
+float current_int2 = 0;
+float angle2;
+float angle_des2;
+float velocity2;
+float velocity_des2;
+float duty_cycle2;
+float angle2_init;
+
+// Fixed kinematic parameters
+const float l_OA=.011;
+const float l_OB=.042;
+const float l_AC=.096;
+const float l_DE=.091;
+
+// Timing parameters
+float current_control_period_us = 200.0f; // 5kHz current control loop
+float impedance_control_period_us = 1000.0f; // 1kHz impedance control loop
+float start_period, traj_period, end_period;
+
+// Control parameters
+float current_Kp = 0.7;
+float current_Ki = 0.2;
+float current_int_max = 1.0;
+float duty_max;
+float K_xx;
+float K_yy;
+float K_xy;
+float D_xx;
+float D_xy;
+float D_yy;
+float xFoot;
+float yFoot;
+float xDesFoot;
+float yDesFoot;
+
+// Model parameters
+float supply_voltage = 12; // motor supply voltage
+float R; // motor resistance
+float k_emf; // motor torque constant
+float nu1, nu2; // motor viscous friction
+
+// Current control interrupt function
+void CurrentLoop()
+{
+ // This loop sets the motor voltage commands using PI current controllers.
+
+ //use the motor shield as follows:
+ //motorShield.motorAWrite(DUTY CYCLE, DIRECTION), DIRECTION = 0 is forward, DIRECTION =1 is backwards.
+
+ current1 = -(((float(motorShield.readCurrentA())/65536.0f)*30.0f)-15.0f); // measure current
+ float err_c1 = current_des1 - current1; // current errror
+ current_int1 += err_c1; // integrate error
+ current_int1 = fmaxf( fminf(current_int1, current_int_max), -current_int_max); // anti-windup
+ duty_cycle1 = current_Kp*err_c1 + current_Ki*current_int1; // PI current controller
+
+ float absDuty1 = abs(duty_cycle1);
+ if (absDuty1 > duty_max) {
+ duty_cycle1 *= duty_max / absDuty1;
+ absDuty1 = duty_max;
+ }
+ if (duty_cycle1 < 0) { // backwards
+ motorShield.motorAWrite(absDuty1, 1);
+ } else { // forwards
+ motorShield.motorAWrite(absDuty1, 0);
+ }
+ prev_current_des1 = current_des1;
+
+ current2 = -(((float(motorShield.readCurrentB())/65536.0f)*30.0f)-15.0f); // measure current
+ float err_c2 = current_des2 - current2; // current error
+ current_int2 += err_c2; // integrate error
+ current_int2 = fmaxf( fminf(current_int2, current_int_max), -current_int_max); // anti-windup
+ duty_cycle2 = current_Kp*err_c2 + current_Ki*current_int2; // PI current controller
+
+ float absDuty2 = abs(duty_cycle2);
+ if (absDuty2 > duty_max) {
+ duty_cycle2 *= duty_max / absDuty2;
+ absDuty2 = duty_max;
+ }
+ if (duty_cycle2 < 0) { // backwards
+ motorShield.motorBWrite(absDuty2, 1);
+ } else { // forwards
+ motorShield.motorBWrite(absDuty2, 0);
+ }
+ prev_current_des2 = current_des2;
+
+}
int main (void)
{
@@ -32,10 +141,37 @@
pc.printf("%f",input_params[0]);
while(1) {
+
+ // If there are new inputs, this code will run
if (server.getParams(input_params,NUM_INPUTS)) {
- float v1 = input_params[0]; // Duty cycle for first second
- float v2 = input_params[1]; // Duty cycle for second second
+
+
+ // Get inputs from MATLAB
+ start_period = input_params[0]; // First buffer time, before trajectory
+ traj_period = input_params[1]; // Trajectory time/length
+ end_period = input_params[2]; // Second buffer time, after trajectory
+
+ angle1_init = input_params[3]; // Initial angle for q1 (rad)
+ angle2_init = input_params[4]; // Initial angle for q2 (rad)
+ K_xx = input_params[5]; // Foot stiffness N/m
+ K_yy = input_params[6]; // Foot stiffness N/m
+ K_xy = input_params[7]; // Foot stiffness N/m
+ D_xx = input_params[8]; // Foot damping N/(m/s)
+ D_yy = input_params[9]; // Foot damping N/(m/s)
+ D_xy = input_params[10]; // Foot damping N/(m/s)
+ duty_max = input_params[11]; // Maximum duty factor
+
+ // TODO: check that this gets inputs correctly?
+ float foot_pts[2*(BEZIER_ORDER_FOOT+1)];
+ for(int i = 0; i<2*(BEZIER_ORDER_FOOT+1);i++) {
+ foot_pts[i] = input_params[21+i];
+ }
+ rDesFoot_bez.setPoints(foot_pts);
+
+ // Attach current loop interrupt
+ currentLoop.attach_us(CurrentLoop,current_control_period_us);
+
// Setup experiment
t.reset();
t.start();
@@ -45,35 +181,151 @@
encoderD.reset();
motorShield.motorAWrite(0, 0); //turn motor A off
-
- //use the motor shield as follows:
- //motorShield.motorAWrite(DUTY CYCLE, DIRECTION), DIRECTION = 0 is forward, DIRECTION =1 is backwards.
-
+ motorShield.motorBWrite(0, 0); //turn motor B off
+
// Run experiment
- while( t.read() < 2 ) {
- // Perform control loop logic
- if (t.read() < 1)
- motorShield.motorAWrite(v1, 0); //run motor A at "v1" duty cycle and in the forward direction
+ while( t.read() < start_period + traj_period + end_period) {
+
+ // Read encoders to get motor states
+ angle1 = encoderA.getPulses() *PULSE_TO_RAD + angle1_init;
+ velocity1 = encoderA.getVelocity() * PULSE_TO_RAD;
+
+ angle2 = encoderB.getPulses() * PULSE_TO_RAD + angle2_init;
+ velocity2 = encoderB.getVelocity() * PULSE_TO_RAD;
+
+ const float th1 = angle1;
+ const float th2 = angle2;
+ const float dth1= velocity1;
+ const float dth2= velocity2;
+
+ // ADD YOUR CONTROL CODE HERE (CALCULATE AND SET DESIRED CURRENTS)
+
+ // Calculate the Jacobian
+ float Jx_th1 = 0;
+ float Jx_th2 = 0;
+ float Jy_th1 = 0;
+ float Jx_th2 = 0;
+
+ // Calculate the forware kinematics (position and velocity)
+ float xLeg = 0;
+ float yLeg = 0;
+ float dxLeg = 0;
+ float fyLeg = 0;
+
+// float Jx_th1 = l_AC*cos(th1 + th2) + l_DE*cos(th1) + l_OB*cos(th1);
+// float Jx_th2 = l_AC*cos(th1 + th2);
+// float Jy_th1 = l_AC*sin(th1 + th2) + l_DE*sin(th1) + l_OB*sin(th1);
+// float Jy_th2 = l_AC*sin(th1 + th2);
+//
+// float xLeg = l_AC*sin(th1 + th2) + l_DE*sin(th1) + l_OB*sin(th1);
+// float yLeg = - l_AC*cos(th1 + th2) - l_DE*cos(th1) - l_OB*cos(th1);
+// float dxLeg = Jx_th1 * dth1 + Jx_th2 * dth2;
+// float dyLeg = Jy_th1 * dth1 + Jy_th2 * dth2;
+
+ // Set gains based on buffer and traj times, then calculate desired x,y from Bezier trajectory at current time if necessary
+ float teff = 0;
+ float vMult = 0;
+ if( t < start_period) {
+ if (K_xx > 0 || K_yy > 0) {
+ K_xx = 180;
+ K_yy = 180;
+ D_xx = 2;
+ D_yy = 2;
+ K_xy = 0;
+ D_xy = 0;
+ }
+ teff = 0;
+ }
+ else if (t < start_period + traj_period)
+ {
+ K_xx = input_params[5]; // Foot stiffness N/m
+ K_yy = input_params[6]; // Foot stiffness N/m
+ K_xy = input_params[7]; // Foot stiffness N/m
+ D_xx = input_params[8]; // Foot damping N/(m/s)
+ D_yy = input_params[9]; // Foot damping N/(m/s)
+ D_xy = input_params[10]; // Foot damping N/(m/s)
+ teff = (t-start_period);
+ vMult = 1;
+ }
else
- motorShield.motorAWrite(v2, 0); //run motor A at "v2" duty cycle and in the forward direction
+ {
+ teff = traj_period;
+ // TODO: reset gains and vMult here?
+ }
+
+ float rDesFoot[2] , vDesFoot[2];
+ rDesFoot_bez.evaluate(teff/traj_period,rDesFoot);
+ rDesFoot_bez.evaluateDerivative(teff/traj_period,vDesFoot);
+ vDesFoot[0]/=traj_period;
+ vDesFoot[1]/=traj_period;
+ vDesFoot[0]*=vMult;
+ vDesFoot[1]*=vMult;
- // Form output to send to MATLAB
- float output_data[NUM_OUTPUTS];
+ // Calculate error variables
+ float e_x = 0;
+ float e_y = 0;
+ float de_x = 0;
+ float de_y = 0;
+
+// float e_x = ( xLeg - rDesFoot[0]);
+// float e_y = ( yLeg - rDesFoot[1]);
+// float de_x = ( dxLeg - vDesFoot[0]);
+// float de_y = ( dyLeg - vDesFoot[1]);
+//
+ // Calculate virtual force on foot
+ float fx = 0;
+ float fy = 0;
+
+// float fx = -K_xx * e_x - K_xy * e_y - D_xx * de_x -D_xy * de_y;
+// float fy = -K_yy * e_y - K_xy * e_x - D_yy * de_y -D_xy * de_x;
+ // Set desired currents
+ current_des1 = 0;
+ current_des2 = 0;
+
+// current_des1 = (nu1*velocity1 + Jx_th1*fx + Jy_th1*fy)/k_emf;
+// current_des2 = (nu2*velocity2 + Jx_th2*fx + Jy_th2*fy)/k_emf;
+
+ //Form output to send to MATLAB
+ float output_data[NUM_OUTPUTS];
+ // current time
output_data[0] = t.read();
- output_data[1] = encoderA.getPulses();
- output_data[2] = encoderA.getVelocity();
- output_data[3] = motorShield.readCurrentA();
+ // motor 1 state
+ output_data[1] = angle1;
+ output_data[2] = velocity1;
+ output_data[3] = current1;
+ output_data[4] = current_des1;
+ output_data[5] = duty_cycle1;
+ // motor 2 state
+ output_data[6] = angle2;
+ output_data[7] = velocity2;
+ output_data[8] = current2;
+ output_data[9] = current_des2;
+ output_data[10]= duty_cycle2;
+ // foot state
+ output_data[11] = xFoot;
+ output_data[12] = yFoot;
+ output_data[13]= dxFoot;
+ output_data[14]= dyFoot;
+ output_data[15]= rDesFoot[0];
+ output_data[16]= rDesFoot[1];
+ output_data[17]= vDesFoot[0];
+ output_data[18]= vDesFoot[1];
// Send data to MATLAB
server.sendData(output_data,NUM_OUTPUTS);
-
- wait(.001); //run control loop at 1kHz
+
+ wait_us(impedance_control_period_us);
}
+
// Cleanup after experiment
server.setExperimentComplete();
+ currentLoop.detach();
motorShield.motorAWrite(0, 0); //turn motor A off
+ motorShield.motorBWrite(0, 0); //turn motor B off
+
} // end if
+
} // end while
} // end main