Published April 18, 2021 © MIT

BenchCounter

Working out is hard. Doing side projects is fun. If you do a side project with 115lbs, you're working out! Watch the video!

BeginnerShowcase (no instructions)1 hour420

Things used in this project

Hardware components

Ultrasonic Sensor - HC-SR04 (Generic)

Itead Raspberry Pi 3 Model B Starter Pack RPI 3 Starter Kit

SparkFun 7-Segment Serial Display - Red

Software apps and online services

Raspberry Pi Raspbian

Hand tools and fabrication machines

Soldering iron (generic)

Story

A couple of my friends love the app Strava for tracking their runs. I don't run. I gathered some items sitting in shoeboxes around my home and made a robot counter for bench press. Here is a video of me testing it out (with robot voice counter):

An ultrasonic sensor sees the bar go past it and the python program running on the Raspberry Pi tracks whether the bar is going up or down and if it should increment the counter. You can see the sensor at the bottom of the taped section on the right post.

If you really wanted to, you could link it up with an app that tracks workouts. I wanted to add a load cell to the rack to weigh the bar before un-racking... but my shoebox load cells are only rated to 50lbs. The original project used a hall effect sensor and I was trying to get it to work with the magnetic barbell... but it was too hard to come down in the same spot of my chest every time to trigger the sensor.

Code

BenchCounterPy

import RPi.GPIO as GPIO
import time, os
import tm1637

GPIO.setmode(GPIO.BCM)
GPIO_TRIGGER = 23
GPIO_ECHO = 24
GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)

Display = tm1637.TM1637(5,4,tm1637.BRIGHT_TYPICAL)
Display.SetBrightnes(1)

def distance():
    GPIO.output(GPIO_TRIGGER, True)
    time.sleep(0.00001)
    GPIO.output(GPIO_TRIGGER, False)

    StartTime = time.time()
    StopTime = time.time()

    while GPIO.input(GPIO_ECHO) == 0:
        StartTime = time.time()

    while GPIO.input(GPIO_ECHO) == 1:
        StopTime = time.time()

    TimeElapsed = StopTime - StartTime
    # multiply with the sonic speed (34300 cm/s)
    # and divide by 2, because there and back
    distance = (TimeElapsed * 34300) / 2

    return distance

def verifyRep(lastRep):
    if (time.time() - lastRep < 1):
        return False
    else:
        return True

def display(counter):
    num = str(counter)
    for i in range(4 - len(num)):
      num = "0" + num
    Display.Show([int(num[0]),int(num[1]),int(num[2]),int(num[3])])

def say(phrase):
    os.system("espeak -s140 -ven+18 -z " + str(phrase))

if __name__ == '__main__':
    
    inBench = True
    firstRep = False
    dir = False # false for down, true for up
    repCounter = 0
    lastRep = time.time()

    try:
        while True:
            dist = distance()
            
            if (dist < 30):
                if (not firstRep):
                    firstRep = True
                    dir = True
                    lastRep = time.time()
                    say("READY!")
                elif (dir and verifyRep(lastRep)):
                    dir = False
                    lastRep = time.time()
                    say("DOWN")
                elif (verifyRep(lastRep)):
                    repCounter += 1;
                    dir = True
                    lastRep = time.time()
                    say(repCounter)
                    display(repCounter)
                else:
                    print("DEBOUNCE")

            time.sleep(0.05)

    except KeyboardInterrupt:
        print("Measurement stopped by User")
        GPIO.cleanup()