As the rear of a wheelchair is often in a wheelchair user’s blind spot, an innovative and low-cost device, BotBeep, was developed to warn the user of elevation changes behind the wheelchair corresponding to holes, steep slopes, and staircases. Thus, BotBeep reduces the risk of falling and turning over. Tests were conducted using a smartphone as a computing device via an image processing technique. Elderly volunteers from the Suang-Lien Elderly Center participated in these tests. This research studies the possibility of incorporating BotBeep into the daily lives of Taiwan’s elderly population.