The morning breeze was a bit chilly, so Chen Hao pulled his coat tighter around himself and squatted by the field, watching the tracks of the "Iron Spine" machine press into the soil. Susan stood beside him, a whiteboard in hand, her pen moving rapidly. Carl was already seated on the traction simulator, his hand resting on the control lever, awaiting instructions. Nana's optical lens swept across the entire experimental field, data streaming into the terminal.

“Let’s begin,” Chen Hao said.

Carl pushed down the control lever, and the "Iron Spine" slowly moved forward. The tracks rolled over the hardened, dry ground, and the plowshare cut into the soil, turning up a neat row of ripples. Susan looked up and a slight smile appeared on her lips.

"It performed well on hard courts, with stable depth and normal power output," she said.

Nana nodded: "The sensors have no abnormal alarms, and the structural pressure is within the design range."

Chen Hao didn't speak, he just stared ahead. He knew the real show was yet to come.

Sure enough, when the "Iron Spine" entered the low-lying, damp area, the machine suddenly sank. The front plowshare plunged into the mud, the machine tilted, and the tracks spun several times before regaining grip on the ground.

"It's sinking!" Karl shouted, quickly pulling back.

The machine stopped, and muddy water flowed down the plow arm. Susan hurried over, measured the depth with a depth gauge, and frowned.

“The plowing depth was nearly 20 centimeters too deep, and it was uneven,” she said, turning around. “The front was dug too deep, and the back was ridiculously shallow.”

Chen Hao walked over, his feet sinking into the wet mud, his shoes immediately getting stuck. He pulled them out with force, walked to the "Iron Ridge," and reached out to touch the connection point of the plowshare.

“It’s not a structural problem,” he said. “It’s the wrong angle at which it enters the soil. The ground is soft, so it burrows in as soon as it’s touched, and the control system can’t react in time.”

Nana pulled up the operation log, and several curves on the screen fluctuated wildly.

"The hydraulic pressure spiked to the upper limit of the threshold within three seconds, triggering the protection mechanism," she said. "The system determined that it was overloaded and automatically relieved the pressure twice."

“No wonder it’s been sporadic,” Carl said, jumping out of the driver’s seat. “It’s like I’m having a cramp.”

Susan flipped through the record sheet in her hand: "We designed the parameters according to the ideal terrain, but the land is not the same length as the drawings at all."

Chen Hao snorted: "Whose land would be adjusted for the hardness of our machine?"

Several people stood around the "iron ridge," but no one spoke. The wind blew across the freshly turned earth, carrying a damp, earthy smell.

“We can’t let it rush around on its own,” Susan broke the silence. “We need to add a depth-limiting wheel to control the maximum depth of the plow.”

“We need to change the tilt angle,” Chen Hao chimed in. “At the current angle, it’s like a bulldozer ramming straight into soft soil.”

Nana immediately pulled up the structural diagram: "Adjustable support wheels can be added to the existing frame, positioned 3.2 meters behind the plow frame, and adjusted via a linkage."

"Are there any materials readily available?" Chen Hao asked.

“A section of the spare drive shaft will suffice,” Susan said. “I brought cutting tools.”

"Then let's not wait any longer." Chen Hao patted the fuselage. "We'll fix it on the spot."

Half an hour later, the newly installed depth-limiting wheel was in place. The wheel was low, only ten centimeters off the ground, but it was enough to keep the plow frame from plunging headfirst into the mud. Susan then adjusted the fixing bolts of the plow arm, reducing the soil entry angle from fifteen degrees to eleven degrees.

“Try again,” she said.

Carl restarted the machine. This time, when "Iron Spine" entered the wetland area, the machine still sank, but the plowshare got stuck on the depth-limiting wheel and didn't continue to plow. The tilling depth was noticeably more stable.

“The depth fluctuation has decreased from 34 percent to 9 percent.” Nana looked at the screen. “The power output is stabilizing.”

Susan made a few notes on the whiteboard: "It's still a bit slippery, especially where the sand meets the soil."

As soon as he finished speaking, the right-side wheel of the "Iron Spine" suddenly veered off course, stepping into a soft spot. The track began to spin freely, causing the vehicle to tilt and nearly overturn.

"Stop!" Chen Hao shouted.

The machine shut down. Carl jumped down and stomped his feet: "The soil here is too loose; I can't get a grip."

“The wheels need more contact surface area.” Susan crouched down to take a look. “Tracks alone are not enough.”

“Add anti-skid rings,” Carl blurted out. “Like on off-road vehicles, weld a raised metal strip around the outer rim of the wheel to break through the mud and increase friction.”

“That makes sense.” Chen Hao looked at Nana. “Can you do it?”

“We have enough material,” Nana said. “We can use scrap gear pieces to weld together and create tooth-like patterns.”

"Let's do it then." Chen Hao shook his hand. "Anyway, we're not going back today."

They skipped lunch and took turns working. Cutting, grinding, positioning, welding—sparks flashed constantly in the sunlight. Susan was in charge of measuring the spacing, Carl held the wheels, Chen Hao held the welding torch, and Nana monitored the welding temperature with a camera.

"If the temperature is too high, the risk of localized melting increases," she warned.

"Okay." Chen Hao loosened his grip. "Let this thing catch its breath."

After the welds cooled, they put the modified wheels back on and checked all the connections again.

At 3 PM, the second full-process test began.

The "Iron Spine" plow once again entered the experimental field. This time, it first traversed the compacted dry land, where the plowshare easily broke through the hard crust and turned the soil smoothly. Upon entering the moist section, the depth-limiting wheels came into play, maintaining the tillage depth within a reasonable range. When it entered the sandy loam mixed zone, the wheels equipped with anti-skid rings firmly gripped the ground, preventing slippage.

"All-terrain capability achieved," Nana announced. "Tillage depth error less than 5%, power load reduced by 12%."

Susan looked at the recorded data and let out a soft sigh: "It's done."

Carl sat on the edge of the field, grinning. "This time it doesn't feel like a tantrum, it feels like we're actually working."

Chen Hao walked around the "iron ridge" and tapped the main beam. The sound was much stronger than in the morning. He looked up at the sky; the sun was already beginning to set.

“Only a spine that can withstand the pressure of the ground can be considered truly iron-willed,” he told Susan.

Susan nodded: "We can try a larger area tomorrow."

"Let's go back to base first." Chen Hao closed his notebook. "We need to organize the data from this time and check if there are any other minor issues."

Nana shut down the monitoring system, and data synchronization was complete. Susan packed up her tools, stuffing wrenches and depth gauges into her bag one by one. Carl pushed over the transport vehicle, ready to take "Iron Spine" back.

"This car is looking better and better," he said as he tied the rope.

"Don't praise it," Chen Hao said. "If you praise it, something bad will happen."

Susan tightened the last buckle: "Then shut up."

They removed some external equipment and confirmed that all components were securely fixed. Nana then did a final check of the circuitry and disconnected the power.

The transport vehicle slowly started moving, the "Iron Spine" lying quietly on the flatbed, its tracks covered in mud and bearing several weld marks. The setting sun shone on the metal shell, reflecting a dim light.

The group walked along the country path towards the base. The wind blew from behind, carrying the scent of earth and metal.

Chen Hao walked at the front, clutching a notebook in his hand. The notebook was already wrinkled from being soaked in sweat, but he didn't let go of it.

Susan lagged a few steps behind and glanced back at the turned-up earth. The clods of earth were neatly arranged, as if measured with a ruler.

Carl started humming a song, completely off-key, but his mood was clearly lighter.

Nana walked at the back, her optical lens slightly rotating, scanning the terrain along the way.

"I suggest scheduling the next test for 7:30 tomorrow," she said. "The temperature will be moderate and the soil moisture will be optimal."

Chen Hao waved his hand: "Let me get a full night's sleep first."

They crossed the last stretch of paddy field ridge, and the base's perimeter wall came into view.

The lights weren't on yet, but faint shadows were cast through the windows. The low hum of machinery could be heard in the distance.

Chen Hao stopped and turned to look at "Iron Spine." It lay quietly on the vehicle, like an old buddy who had just finished a job.

"I'll have to keep bothering you tomorrow," he said.

The truck's wheels rolled over a rock, making a slight vibration.