It was like a scene out of a movie. Vincenzo Piscopo, the CEO of United Spinal Association, was about to give a speech on the final day of the organization’s annual Roll on Capitol Hill. He rolled up a ramp to the stage with the help of a Permobil SmartDrive MX2+ power-assist device. But when he tried to slow the SmartDrive after ascending the ramp, it wouldn’t decelerate. It pushed him across the stage as he repeatedly tried to stop it, and eventually forced him off the stage. He crashed into a 10-foot-high curtain before falling 3 feet to the ground and pulling the curtain down on top of him. “It just happened so quickly,” Piscopo says. 

People screamed and rushed the stage. Fortunately, Piscopo was OK — the drape helped arrest his fall and stopped him from hitting his head. He injured his wrist but otherwise escaped serious injury. After dusting himself off, he was able to get back to his speech, making a joke about starting with a bang. For those of us in attendance, it was good to see he was OK, but it was clear the mishap could have been much worse.  

I flashed back to a moment when I was testing an earlier-generation SmartDrive. I was pushing along a city sidewalk and couldn’t get the unit to stop. It pushed me into a stop sign, up onto my front casters, where the unit then rotated on my axle and jammed underneath my chair. I was stuck until I transferred to the ground and wrestled the SmartDrive back into place. As with Piscopo, my incident could have been worse. I was lucky the stop sign was there, otherwise I would’ve been pushed off the curb onto a busy city street.  

Incidents like these bring up many questions. Was there something wrong with Piscopo’s specific unit? How often does something like this happen? Is a Bluetooth connection really a good idea for a power assist device? And why is there no easily accessible kill switch on the SmartDrive? 

The Recall 

To answer my first question about any problems with Piscopo’s specific unit, I talked with Richard Foshee and Audra Watt, who both work in marketing at Permobil. The short answer is yes: Piscopo’s SmartDrive, or more specifically the smartwatch that he was using to control the unit, had a known software malfunction that could cause the unit to not respond to his attempts in stopping it. Since early 2022, Permobil has received 34 other complaints from users who had the same failure-to-disengage issue with watches sold with SmartDrive units from May 2019 to Feb. 10, 2023. (The watches may be branded as the Mobvoi TicWatch E2, the PushTracker E2 or the PushTracker E3.) “Anytime that we hear of a product complaint, we are required and obligated to respond very quickly, and not only document the issues but do a full investigation,” says Foshee. 

According to Watt, in “most instances, the failure could not be duplicated during the complaint investigations and [the] root cause was not found. In early 2023, through unrelated design and development activities, Permobil identified a software issue with the [SmartDrive] MX2+ application operating on Android Wear OS [smartwatch operating system] that was [the] cause of the previous customer complaints.” 

They completed an investigation of that root cause in early April 2023, and on May 10 Permobil issued what they call a “voluntary field correction” — the FDA calls it a product recall — on affected units, numbering 6,196 sold worldwide. According to the recall, when “multiple processes are running on the watch’s Central Processing Unit, … the application may fail unexpectedly. If this happens, the motor on the power assist device continues to run and the user may not be able to stop the device using tap gestures.” 

This is likely what happened to Piscopo. The fix for his specific issue is easy: a software update. The problem was, Piscopo didn’t receive notice of the recall until July 12, three weeks after his incident. “A bit too late,” he says. 

Foshee with Permobil says that users could have had delays getting their notices because of the steps involved: Permobil had to inform dealers, then dealers had to look through their records and forward the notice to customers who purchased the product. Foshee says anyone who has questions or concerns about whether they are affected, or who needs assistance correcting their unit, can either contact their provider directly, call Permobil’s customer experience team at 800/736-0925, or visit Permobil’s support page. 

The Problem 

To find out about my second question — how often other users have control issues — I turned to Erin Gildner, the director of chapter relations for United Spinal. It’s Gildner’s job to coordinate with United Spinal’s 47 member-chapters across the county. She knows a lot of wheelchair users. Gildner was in the audience when Piscopo flew off the stage, and as it turns out, had her own incident with a SmartDrive when she first bought one. “I was on a trip with my family, excited to be using the SmartDrive because I was going to be doing a lot of pushing and I didn’t want to wear myself out just getting around,” she says. “But it wouldn’t always respond to me, and at one point it kept pushing me toward a mom and toddler while I tried to stop it. Fortunately, I didn’t run into them but that’s only because someone grabbed the toddler and pulled her out of the way.”  

The incident left her shaken, and the SmartDrive has been sitting in her garage ever since. “I don’t feel comfortable using it,” she says. “If you talk to other wheelchair users who have a SmartDrive, almost everyone has a story about an incident with it.” 

Gildner had the original PushTracker, different from the E2 model Piscopo was using that was subject to the recall. I was using the same, older-style device during my stop sign incident. A Facebook post in an SCI group with over 10,000 members yielded dozens of responses from users who had issues with the SmartDrive not responding to physical cues or starting without warning. Respondents experienced a variety of connection issues, including with the older-style wrist device and the Apple Watch, which can also control a SmartDrive.  

I asked the Permobil reps whether they knew of any issues with controllers other than the TicWatch E2/PushTracker E2. Watt says that the newer PushTracker E3 operated on the same Wear OS system as the E2 model and is also subject to the recall. Additionally, Permobil did identify issues with the first PushTracker, which was the original Bluetooth controller developed by Max Mobility, noting “limitations with its hardware and Bluetooth connectivity that could cause a lost connection, but the SmartDrive was designed to shut off if this happened.”

Mine certainly didn’t shut off when it pushed me into a stop sign, but I also didn’t file a complaint with Max Mobility, which owned SmartDrive at the time. It was hard to tell whether it was user error, or the device had actually malfunctioned, or if I just needed more experience operating the unit in tight quarters.  

Still, even if a controller doesn’t have a specific fault like the one leading to the recall, it’s worth asking whether a Bluetooth-reliant wearable device can maintain a sufficiently stable connection for controlling your power of movement. Many SmartDrive users I spoke with have moved away from a wristwatch being their only connection, and some that do use only a Bluetooth controller will make sure to turn the unit off around busy streets or other locations where an unresponsive or hyperresponsive unit could cause serious damage.  

The Learning Curve

Bob Vogel, a paraplegic and longtime user of the SmartDrive, loves his power assist unit. “It has saved my shoulders and I’m grateful for it,” he says. But it’s something he’s had to fine-tune to be able to use safely. “I’ve found in the early days that it would just take off when I was in the middle of telling an animated story,” he says. “Thank goodness I wasn’t on a street corner or a stage or anything like that.”  

Vogel says he’s found that the watch will often have issues, mainly failing to engage the unit, when he’s in a busy public place like an event center, where there are a lot of people and a lot of Bluetooth devices being used. But he says that most of his early incidents with the SmartDrive were due to operator error. “There absolutely is a learning curve,” he says. For manual wheelchair users who aren’t used to operating a powered device, it is imperative to learn how to use it and iron out any potential issues in a safe environment first. “It’s a bit like learning how to drive a car,” he says. He recommends lowering the SmartDrive speed when first learning to use it, and he keeps the sensitivity settings of his unit set low, so that it takes more forceful movements to engage the motor.  

But even with proper training, having the control unit attached to your wrist can cause problems. Piscopo has owned his SmartDrive for a few years and uses it regularly while traveling. He normally turns the unit off with his watch whenever he stops somewhere, but it’s easy to forget. Not long before Piscopo was pushed offstage at ROCH, he was giving another talk when the unit pushed him into a table, knocking off some drinking glasses. He says that nearly every time he uses his SmartDrive, it has issues of starting when he doesn’t want it to. “I talk with my hands,” he says. “It’s really hard to stop being Italian.” 

A Better Way Forward? 

My third question — why the SmartDrive doesn’t have an easily accessible kill switch — turns out to be moot. It does now. In the past few years, Permobil has released a few different wired-control options.  

There is the SpeedControl Dial, basically a small wheel that mounts on your wheelchair frame at about cushion-level. You rotate it forward to start the SmartDrive, keep rolling it to go faster, and then roll it in reverse to slow and stop the unit. One Facebook responder said she had issues all the time with controlling her SmartDrive by the TicWatch and Apple Watch. She switched to the SpeedControl Dial, which she calls her “only reliable means of using it.”  

The speed dial isn’t for everyone though. Bob Ness, a C6 quadriplegic who lives in Chicago and produced the video embedded in this article, says he was offered the SpeedControl Dial by his durable medical equipment supplier. “Because of where it mounts, I couldn’t put it on,” he says. “It blocked the part of my frame that I use to transfer.”  

Other wired options include SwitchControl, which offers two programmable buttons. It attaches to your chair’s frame and is much smaller than the SpeedControl Dial. In the most common setting, you press the button once to turn the unit on; press and hold to bring the SmartDrive up to the maximum speed you’ve set; and press again to disengage the motor. As one Facebook responder put it: “Get the physical switch as a backup. Even if you’re using the watch, the physical button will override and stop. You’ll have to relink [the watch], but that’s what I do.”  

Permobil also has a Buddy Button, similar to the SwitchControl but with a larger button that is easier to operate with limited hand function.  

As of last year, Permobil made the SpeedControl Dial and SwitchControl buttons the no-charge options for controlling the SmartDrive. Now you must pay for the watch separately, or use an Apple or Samsung watch if you have one. You can also upgrade to a SpeedControl button with a mono jack, that you can use with other adaptive switches. The wired controllers come with zip ties or Velcro straps for anyone who wants to be able to take the wires off their chair during travel.

After her incident with the toddler, Gildner bought a SMOOV one power-assist device similar to the SmartDrive, with a wired, wheel-style controller. “I love the predictability and safety that comes with having a speed dial,” she says. The SMOOV one will also automatically shut off the motor if you brake using your handrims, which Gildner says comes in handy when she doesn’t have time to reach the dial. Now that a speed dial is available with the SmartDrive, Gildner says she’d consider switching back. “[The SmartDrive] is more agile, lighter and easier to use when attached to your chair [and] not powered on,” she says. “If the speed dial solves the problem of unpredictability, that would be a game-changer.” 

Piscopo agrees. He’s getting a SpeedControl Dial and doesn’t plan on using his SmartDrive until he has the wired controller installed. He saw firsthand how dangerous a lack of control can be, and he isn’t eager to test his luck again.